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An empirical model of air displacement by revolving doors
Accepted Manuscript Title: An empirical model of air displacement by revolving doors Author: Lin Du Radu Zmeureanu Ted Stathopoulos PII: DOI: Reference:
S0378-7788(13)00748-2 http://dx.doi.org/doi:10.1016/j.enbuild.2013.11.041 ENB 4642
To appear in:
ENB
Received date: Revised date: Accepted date:
26-2-2013 4-11-2013 9-11-2013
Please cite this article as: L. Du, R. Zmeureanu, T. Stathopoulos, An empirical model of air displacement by revolving doors, Energy and Buildings (2013), http://dx.doi.org/10.1016/j.enbuild.2013.11.041 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
*Manuscript
An empirical model of air displacement by revolving doors Lin Du, Radu Zmeureanu* and Ted Stathopoulos Centre for Zero Energy Building Studies, Department of Building, Civil and
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Montreal, Quebec, CANADA H3G 1M8
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Environmental Engineering, Concordia University,
*
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Corresponding author; Phone: 1-514-848-2424/3203 Email: [email protected]
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Abstract
This paper presents an experimental study on a reduced scale model to quantify
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the air displacement due to the revolution of revolving doors. The results show that the
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air displaced by revolving doors increases only slightly with the rotation speed, and is
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about two orders of magnitude less than values currently used in the calculation of air infiltration rate, for the same conditions. The correlation-based models developed in this study from experimental data are proposed to be used for the estimation of the air
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infiltration rates of existing revolving doors that are installed in large commercial or institutional buildings.
Keywords: Air infiltration, Revolving door, Measurements, Reduced-scale model
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1.
Introduction
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Revolving doors are widely used as entrances of large public buildings such as office buildings, shopping malls and hotels, which have high traffic of people. This four-
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wing revolving door type keeps the entrance closed all the time to reduce the air
infiltration and hence minimizes the energy needs for heating caused by the entrance [1].
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The air exchange through a revolving door can be calculated as the sum of (1) the air
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leakage through the gaps and seals between the wings and the door housing, due to the pressure difference across the door, caused by stack and wind effects; and (2) the air
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displacement due to the revolution of the door, evaluated in terms of door rotation speed and temperature difference between indoor and outdoor environments.
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Schutrum et al. [2] measured the air exchange on a full-scale revolving door
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installed at the entrance of a laboratory using a tracer gas technique with hydrogen. The hydrogen concentration was measured with a cathetometer, which detected changes in the
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thermal conductivity of mixture air-gas, due to the presence of hydrogen. The measurements were made with two sets of new seals and one set of worn seals, which still had a good contact with the door housing. The results reveal that at the stationary condition the air infiltration through door seals depends on the condition of seals, the wing position and the indoor-outdoor pressure difference. When the door rotates, the air infiltration of a motor-operated revolving door is presented as a function of inside-outside temperature difference and rotation speed. The infiltration of the manually-operated revolving doors was presented in terms of rotation speed, inside-outside temperature difference, outside wind velocity and indoor air movement. 2
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ASHRAE Standard 90.1 [3] and Load Calculation Manual [4] recommended the estimation of heating load due to cold air infiltration through revolving doors of commercial or institutional buildings based on reference [2] when measurements from
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manufacturers are not available.
Zmeureanu et al.[5] measured the air infiltration through gaps and seals of four
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revolving doors of a university building, at stationary conditions, by using the blower
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door technique. The air infiltration rate of those doors were compared with
recommendations from ASHRAE Standard 90.1 [6] and the MNECCB [7], as well as
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with the air infiltration rate of a new revolving door tested by an independent consultant at a manufacturer’s facility. The leakage rates for all four doors greatly exceeded the
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values specified by both standards as well as the results from [2]. Those doors have been
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in operation for more than 30 years and the seals lack of maintenance, while the door
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used by [2] was installed properly for the experimental purposes. In the same study we also evaluated the impact of door rotation speed on the air infiltration rate. In the case of the door with seals of acceptable quality, the air flow rate
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through the door did not change compared with the case of not revolving door. Hence, the air displaced by the revolving door was negligible. In the case of two doors, which have only three vertical seals, the data acquisition system was not able to collect reliable data because of large fluctuations of the pressure differential across the doors. Air flow through a revolving door when it rotates was examined in a water chamber by Allgayer and Hunt [8-9] using a scaled model approximately 1/10th of the full size. A transparent tank was partitioned into two compartments and a rectangular opening in the partition housed the revolving door. The fresh and salt-water solution, which produced 3
Page 3 of 40
the density difference, was used to represent temperature difference through the doorway. The experiment focused on the flow pattern and the effect of the door rotation rate and temperature difference across the doorway. It was concluded from the experimental
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results that when the rotation speed exceeds a critical rotation rate, at same indoor-
outdoor temperature difference, the exchange rate becomes independent of the rotation
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speed and it remains constant. This regime is called buoyancy-limited-constant. For
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rotation rates lower than the critical value, which occurs in the revolution-limited regime, the air exchange increases with the rotation speed. If the rotation rate exceeds the
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maximum value of the buoyancy-limited-constant regime, the air exchange decreases. Allgayer [10] presented the theoretical and technical description of the scaled modeling
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technique, the results and a set of design charts to estimate the air exchange in terms of
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revolution rate and external temperature.
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Cullum et al. [11] estimated the annual energy consumption for heating/cooling of a building on the MIT campus. The graphs of Schutrum et al. [2] were used to estimate the air infiltrated through revolving doors, and the graphs of Min [12] were used for
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swinging doors. The amount of energy found was near 100.000 kWh. This seems to be over-estimated as it is enough to heat 6.5 single-family houses in one year, or to light a 100 W bulb for 37.8 years. Perhaps this is due to the use of over-estimated air infiltration rates from [2].
The ASHRAE Research Project 1236-RP [13] evaluated the U-value of several non-residential door products, including a four-wing revolving door; the U-value obtained by 2D CFD modeling was about 3.6 W/(m2·°C) while the measured value was 3.48 W/(m2·°C). The air leakage when the door was not revolving was measured based 4
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on the NFRC 400 [14]; when all four wings were in contact with the curved sidewalls, the air leakage was 8.9 L/(s·m2) at 75 Pa pressure difference. The case of door revolving was not, however, among the project objectives.
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The ASHRAE standard 90.1 [3] and the Energy Conservation Building Code 2006 [15] specified that the air leakage for commercial entrance (swinging or revolving doors)
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shall not exceed 5.0 L/(s·m2 of the door area) when tested at 75 Pa pressure difference.
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The MNECCB [7] specified that air leakage rate through swinging, revolving and sliding doors should not be more than 17 L/s for each meter of the door crack, which is
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equivalent to 68.0 L/(s·m2 of the door area). These standards are vague about the conditions of the application of the recommended values. It can be assumed that, for
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swinging and sliding doors, the recommendations are made for closed doors. However, it
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turn.
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is not clear whether the values should apply when revolving doors are still or when they
The inconsistencies found in the previously mentioned studies on air infiltration due to the movement of revolving doors, and the need for new information for the analysis
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and improvement of the provisions of standards or by-laws prescriptions and to increase the accuracy of estimations of heating loads and energy use, were the principal forces to carry out the present experimental study. The two components of air infiltration through a revolving door, that is the air
leakage and air displacement, might occur simultaneously, for instance when a door with worn seals is in motion. The air leakage through the gaps and seals of an existing door can be easily measured by using, for instance, the blower door technique, while the air displacement is more difficult to measure in-situ. For this reason, this study focused only 5
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on the evaluation of the air displaced by the door rotation. The measurements from a reduced-scale physical model were used along with the heat balance method to estimate the air displacement due to the door rotation. Some correlation-based models were first
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developed for the reduced-scale physical model, and then these models were converted to
Methodology
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2.
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prototype conditions to allow for the in-situ estimation of air displacement.
A reduced-scale physical model was manufactured to simulate a revolving door in
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the Energy Efficiency laboratory of Concordia University. An airtight box with a reduced-scale revolving door on the front side (Fig. 1) was installed in a climatic
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chamber in which the temperature was kept between 0.5°C and 2°C. The reduced scale
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four-wing revolving door was made of Plexiglass of 5 mm thickness, with a vertical
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squared shaft of 14 mm width, on which the four wings were connected. The seals of 5 mm thickness, made of a brush-type gasket, were installed on the top and bottom of each wing as well on the vertical side, pressing on the door housing. An electric motor was
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installed on top of the vertical shaft to control the door rotation speed. The box represented the hall of a building, and the climatic chamber (3.65 m × 2.45
m × 2.03 m) represented the outdoor environment. Inside the box there was a heater to control the air temperature (e.g., around 20°C), and a small fan of 0.4 W, which circulated the indoor air to create a uniform temperature distribution. In order to reduce the heat losses through the box walls, two layers of expanded styrofoam of 0.05 m thickness each were mounted on the outside surface of the box. One layer of aluminum
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paper was taped on the outside surface of insulation to reduce the heat exchange by radiation between the box and environmental chamber. The net air flow rate, which was only due to the rotation of revolving door, was
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calculated from the heat balance equation applied to the air inside the box, by using
measurements of air temperatures inside and outside the box, and the electric power input
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to the heater and fan installed in the box. The direction of air flow leaving the revolving
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door was also determined from measurements of air temperature and visualized by
2.1
Reduced-scale physical model
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infrared thermography.
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The prototype and the physical model must be similar in terms of linear dimensions,
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shape, and airflow pattern [16]. Only when the independent dimensionless groups are the
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same in scaled-model and prototype, the relationships between scaled model and fullscale prototype are correct.
The model used in this experiment was a 1/10 scaled model, so the geometric scale
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ratio λL was:
Dp L
Dm
10
(1)
where: D = diameter of the revolving door; the subscript “p” refers to the prototype (real life) dimension; Dp =2.10 m, and “m” refers to the reduced scale model; Dm =0.21 m. The door height is Hm = 0.21 m. The scaled and prototype models had the same Reynolds (Re) number, of about 2900, which was defined in terms of angular speed ω, in rad, and the diameter of the 7
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revolving door D [17]. Since the air was used as fluid in both model and prototype, the kinematic viscosity is equal, and therefore the angular velocity factor λω was written as
p
(
1 100
(2)
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m
Dm 2 ) Dp
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follows:
V
Vm
3 p Dp 3 m Dm
1 10 3 10 100
where: V = volumetric flow rate, in L/s.
(3)
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Vp
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The fan law [15] was used to define the air flow factor λV as follows:
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The air leakage was eliminated by installing good horizontal and vertical seals on each wing. The only air exchange between outdoor and indoor environments was due to
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the rotation of revolving door. Under these conditions, there was no gravity force, and
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therefore the similarity of Froude number was not required.
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2.2
Measurements
A Data Acquisition System (DAS) type 34970 (Agilent) was used for collecting
the measured data and controlling the revolving speed (Fig. 2). Two modules with 20 channels on each to record temperature and electrical current, and one multifunction module to record the total number of rotations of the door were installed in the DAS unit. The voltage and current signals for the heater were recorded by the DAS.
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There were four groups of thermocouples (T type, special limit), indicated in Figure 3 as A, B, C, and D, installed outside and inside, very close to the door to measure the temperature of air moved by the turning segments. All the small “T”s in circle (Fig. 2)
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represent the location of thermocouples. The “h” subscript indicates a higher location of thermocouples (at 0.25·Hm from the door top), and the “l” subscript indicates a lower
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thermocouple (at 0.25·Hm from the door bottom). There are also two thermocouples, Mo
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and Mi, at the middle height and center near the revolving door. Mo is the thermocouple
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installed outside and Mi is the thermocouple installed inside the box. The fan and the door motor shared one power supply system, and their voltages and
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currents were recorded by the DAS as well. The DAS not only reads the voltage input to the motor, but can also control the revolving door speed. The rotation speed was
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measured as well.
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In addition to those thermocouples, ten thermocouples were installed in several experiments in a horizontal plan in the front center outside the revolving door to identify
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the air temperature distribution that can give an indication about the direction of air movement, generated by the revolving door (Fig. 4). To visualize the air flow direction when it leaves the revolving door, a mosquito
screen fixed on a frame was placed in horizontal position outside the revolving door. The screen temperature, which is influenced by the warmer air flow coming out from the box, was measured with an infrared camera using the technique explained in [18].
2.3 Heat balance equation 9
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The air mass flow rate brought in the box when the door rotates is calculated from the heat balance equation applied to the air inside the box over the time interval Δt: Q fan
Qloss
(4)
Qdoor
where: ΔQ = energy change inside the experimental box in J;
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Qheater = heat generated by the heater, in J;
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Qfan = heat generated by the small fan, in J; Qloss = heat loss through the box walls, in J;
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Q Qheater
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Qdoor = heat loss due to the cold air brought in the box when the door rotates, in J. The electric motor driving the door was installed outside the box, and therefore the
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electric power input did not affect the heat balance inside the box. The electric power input to small fan installed inside the box was converted entirely into heat.
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The following equations apply: Q m2 c p T2
m1 c p T1
(
2
T2
1
T1 ) c p Vbox
(5)
where: ρ1 = air density at the beginning of the time interval Δt;
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ρ2 = air density at the end of the time interval Δt; T1 = initial temperature inside the box at the beginning of the time interval Δt; T2 = final temperature inside the box at the end of the time interval Δt; cp = specific heat of air, in J/(kg·°C); and Vbox = internal volume of the box = 0.146 m3. Qheater = Δtstep·
Vheater, j I heater, j
(6)
j
10
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where: Δtstep = time step between each recording j, equal to 10 s; Vheater = electrical potential difference (voltage) applied to heater, in V;
Qfan = Δtstep·
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Iheater = electric current for heater, in A; V fan, j I fan, j
(7)
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j
where: Vfan = electrical potential difference (voltage) applied to the fan, in V;
t step
(Ti
To ) j
(8)
an
Qloss U A
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Ifan = electric current for fan, in A;
j
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where: U = overall heat transfer coefficient, in W/(m2·K);
A = exterior surface area of the experimental box, in m2;
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Ti = average indoor air temperature of the box, in °C;
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To = average air temperature of the environmental chamber, in °C; Qdoor
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minf,m c p
t step
(Ti
To ) j
(9)
j
where: minf,m = air mass flow rate, in kg/s, due to the motion of reduced-scale revolving door.
The air volumetric flow rate through the revolving door Vinf,m (L/s) is:
Vinf,m 1000
minf,m
(10)
where: ρ = air density at 1°C (the average temperature in the environmental chamber) and atmospheric pressure = 1.29 kg/m3 [15]. The air temperature inside the box was kept constant at different set point values between 16 and 40°C, and the air outside the box 11
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was between 0.5 and 2°C. A constant average value of 1.005 J/(kg·°C) for the specific heat was used in calculations, as the impact of air temperature is negligible within the
3.1
Rotation speed
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Experimental results and discussion
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3.
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range of variation; the error is about 0.3%.
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Prior to the experimental measurements, in order to define the range of rotation speeds of revolving the doors, field observations were made on one office building and
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two university buildings. The number of people passing through the revolving doors and the number of rotations in each five-minute interval were recorded for several hours for
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each building. Data collected were converted to the traffic rate, in persons per hour, and
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the average rotation speed Np in rotations per minute (rpm). The rotation speed of revolving doors in the field studies varied from 0.8 to 6.2 rpm. At the same traffic flow
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rate, the average rotation speed observed in this study (Fig. 5) is lower than that presented by [2]. It should be noted, however, that the present study included the idle time, while data from [2] excluded the idle time. Since the purpose of visual investigation carried out at the beginning of this study was only to identify a reasonable range of rotation speed, the difference between two experimental results would have no impact on the results of this study. In the reduced-scale model, the experiments were carried out at different rotation speeds Nm ranging from 19 to 370 rpm, corresponding to 0.19 to 3.7 rpm in the prototype
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doors. Higher rotation speeds were not attempted because of concerns about the physical robustness of the rotation mechanism.
U·A-value
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3.2
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The overall U·A-value, used in Equation 8, was calculated from the heat balance
the door not moving:
U A
V fan I fan ) j
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(Vheater I heater j
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equation of air inside the box by using preliminary results at steady-state conditions with
(Ti
(11)
To ) j
j
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The calculated UA value was between 0.72 and 1.26 W/(m2·K) including the convection on the inside surfaces that was generated by the small fan that runs
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continuously. When the door rotates, the air movement increases the convective
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coefficient on inside surfaces above that value. The air displacement rate calculated from measurements was therefore a conservative high value, as the increase of UA value
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would lead to a smaller estimated air displacement. The following relationship between the overall U·A-value, in W/K, and the indoor temperature Ti from about 15.5°C to 43.3°C, at To from 0.5°C to 2°C, was obtained by using the least-squares method, with the coefficient of determination R2 = 0.96: U·A = 0.4181 + 0.0197·Ti
3.3
(12)
Air displacement rate in the reduced-scale model
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Figure 6 shows the volumetric air displacement rate in the reduced-scale model, under different rotation speeds and indoor temperatures, at outdoor air temperature To ranging from 0.5°C to 2°C. The results at indoor temperature of 40°C are within the same
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range of the results as experiments around 20°C, including the limited measurements at 25°C. Hence, the results from this study are not affected by the air temperature difference
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within the limits of this study. By linear regression on the data shown in Figure 6, the
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volumetric air displacement rate Vinf,m, in L/s, through the reduced-scale revolving door is expressed as function of the rotation speed Nm of the reduced-scale model, in rpm, as
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follows:
(13)
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Vinf,m = 0.0006·Nm + 0.2148
The regression model shows that the air displacement rate is not sensitive to the
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rotation speed of revolving door, within the limits used in this study. The coefficient of
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determination R2 = 0.51, due to the dispersion of experimental points around the trend line, indicates that other variables, not identified in this study, have an impact on the air
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displacement rate in addition to the door rotation speed. Such variables could be the density difference between the cold and warm air, the temperature gradient inside the box, and the increase of UA value.
By using dimensionless criteria presented in section 2.1 along with Equation 13,
the volumetric air displacement rate Vinf,p, in L/s, in the prototype door is expressed as a function of the rotation speed Np, in rpm, as follows: Vinf,p = 0.6·Np + 2.15 3.4
(14)
Infrared visualization 14
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To visualize the air flow direction when it leaves the revolving door, the infrared thermography was used, and infrared images were recorded at different rotation speeds and with different conditions of seals – with full seals around the wings and with no
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vertical seals on the side of wings. A mosquito screen fixed on a frame was placed in horizontal position outside of the revolving door, at mid-height of the door. The infrared
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camera was placed above the screen. The air flow coming from indoor environment
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results in different temperature distribution on the net and this temperature difference can be shown by the colorful infrared pictures. In these images, the more reddish color
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represents higher temperature and the more bluish color represents lower temperature. Figures 7 and 8 show the infrared images when the door has seals around the four wings,
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and the rotation speed of 50 and 300 rpm, respectively. The door rotates
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counterclockwise. The infrared images show that the warm air brought from inside by the
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door movement is pushed towards the door housing. The area of expansion of warm air is very narrow near the door, as a result of air being re-absorbed inside the door, when the door bay closes. The same trend is expected to occur near the door inside the box, when
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the colder air enters the box. Therefore the air displaced by the door rotation has a small impact of the heat balance of the box interior, which leads to the estimation of low air displacement rate. 3.5
Error analysis
The measured physical quantities are: voltage and current inputs to the heater and fan installed inside the box; dimension of the box; air temperature; and time. The measurement error of DC voltage is ±0.004% for the small fan and of AC voltage is 15
Page 15 of 40
±0.06% for the heater. The 0.1Ω electricity resistance installed in the circuits has a relative error of ±1%. The bias uncertainty of thermocouples reading, from Siemens Building Technologies, is 0.005·T+0.3 that gives the uncertainty of 0.4°C, or a relative
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uncertainty of about 2%. The propagated uncertainty of calculated air infiltration rate, based on measurements, is between 0.023 and 0.050 L/s, or the relative uncertainty is
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3.6
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between 5 and 22%. Discussion
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The volumetric air infiltration rates at different rotation speeds measured in this study are smaller than the results from [2]. Further discussion is necessary since there is
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no other publication available for the comparison of the air flow rate caused by rotation of the door.
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The first comparison is made between the air flow rate supplied by a centrifugal
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fan and the air flow rate pushed in the building by a revolving door, as they may have similar air dynamics. The performance data of a centrifugal fan with the same dimensions
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as the reduced-scale revolving door is selected from a manufacturer’s catalogue [19] for this comparison. This is a centrifugal fan with diameter of 0.204 m that gives an air flow rate of 45 L/s at 2920 rpm. Based on the fan law [16], the air flow rate at other rotation speeds is calculated as follows:
V2
V1
D23 D13
2 1
0.0168
2
(15)
Figure 9 compares the air infiltration rate from (1) the reduced-scale model, (2) the centrifugal fan, and (3) from [2] converted at the reduced-scale dimensions. The values presented by [2], for 10-15°C temperature difference and at several rotation speeds, range 16
Page 16 of 40
from 10 to 29 L/s, suggesting that a revolving door pushes much more air inside a building than a centrifugal fan of the same size and rotation speed, with corresponding values from 0.3 to 6.2 L/s. This is impossible! The results of this study, with values from
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0.25 to 0.48 L/s, are much lower than those of centrifugal fan, as expected. This relative comparison shows that the results from this study show that the air displaced by
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revolving doors is about two orders of magnitude less than values currently used in the
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calculation of air infiltration rate based on [2].
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A second comparison is made between the annual energy use for heating the cold air infiltrating due to the rotation of a revolving door according to data from [2] and data
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from present study. The calculations were carried out by using the degree-day method. The rotating door was assumed to be located in Montreal, where the design outdoor air
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temperature for heating is -23°C and the number of heating degree-days is about 4500ºC.
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For the indoor air temperature of 18°C, the electric demand for heating only the cold air displaced into the building by the revolving door is about 13 kW based on [2]. The
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corresponding annual heating energy usage is estimated at 23,600 kWh, which equals the average annual energy consumption of a house in Montreal. This shows that the air infiltration rate from [2] is overestimated. However, if data from present study were used, the electric heater for the same case has a capacity of only 0.2 kW and the annual energy consumption is about 300 kWh. Therefore, we consider more credible the experimental data from this study. When the results from the reduced-scale model are converted to prototype doors, at rotation speeds between 0.2 rpm and 3.6 rpm, the air infiltration caused by the rotation of a door with good seals varies from 2.3 L/s to 4.4 L/s. These values 17
Page 17 of 40
correspond to 0.5-1.0 L/s·m2 of the door area or 10-20% of maximum values given in [3, 15]. The recommended limitation of the air infiltration through revolving doors, as presented in some standards, is most likely only for the part of air infiltration
ip t
through gaps and seals when revolving doors do not move. The air displacement due
cr
to the revolution of the door should also be included in those standards.
us
3.7 Air displacement through revolving doors with different conditions of seals The results presented in section 3.3 are for a reduced-scale revolving door having all
an
four wings with seals of good quality in contact with the door housing. Figure 10
M
compares those results with those obtained with the same experimental setup from (1) one door without two vertical seals, and (2) another door without any vertical seals [20].
d
As expected, the air displacement rate due to the door revolution increases when the
te
seals are removed, particularly at high rotation speeds. This is an extreme case of seals without proper maintenance or replacement. The results underline the importance of
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
maintaining the seals’ quality around the wings for reducing the air infiltration and, therefore, the energy use for heating.
3.8
Dimensionless air temperature
To normalize the results for different indoor and outdoor temperatures, which
slightly varied from one experiment to another, the dimensionless air temperature θx is calculated at each selected location x near the door opening (Fig. 3) when the door rotates:
18
Page 18 of 40
x
Tx To Ti To
(16)
where Tx = temperature at location x, in °C. Each temperature is the average value over
ip t
the last five minutes of the recording period. The revolving door is turning counterclockwise. For each group A, B, C and D, the dimensionless temperature is
cr
calculated using the average value of the “h” and “l” test points (see Fig. 3). The “h”
us
subscript represents a higher thermocouple, and the “l” subscript represents a lower thermocouple.
an
Figure 11 shows that the dimensionless temperatures θB and θC (inside the box) are higher than θA and θD (outside the box). When the rotation speed is greater than about
M
100 rpm, θC remains constant at about 0.75. This is another indication that the cold air displaced by the revolving door does not increase with the increase of rotation speed.
te
d
Since θB > θC regardless of the rotation speed, the thermocouple installed at location C is more affected than at point B by the cold air brought inside the box by the revolving door; hence the displacement air is mostly directed towards location C.
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
The measurements from the additional thermocouples installed outside the
revolving door in the horizontal plan were also used to identify the direction of air flow leaving the revolving door. Figures 12 and 13 show the air temperature distribution outside the door at the rotation speeds of 173 and 296 rpm, respectively, both at the indoor air temperature of 20°C. The values presented are the average air temperature Tx, in °C, of last five minutes of the measurement period. The dimensionless temperature θx is also presented within brackets. In all cases, when the door rotates counterclockwise,
19
Page 19 of 40
the air is pushed along the tangent to the door housing. Figure 12 suggests that a proportion of air pushed by the revolving door re-enters the door segment. The results presented in this section are supported by the infrared thermography
ip t
(section 3.4) that the air brought in by the door rotation is mostly re-absorbed inside the
3.9
us
cr
door, when the door bay closes.
Measurement of air infiltration through existing revolving doors
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It is difficult to use the same approach as in the laboratory to measure the air displacement rate through an existing revolving door in a large building. It would be
M
more practical if the air displacement rate can be estimated based on some site measurements of variables with significant impact such as rotation speed N of revolving
te
d
door and air temperature at several locations near the door (e.g., at A, B, C and D locations in Figure 3). Therefore a two-step approach was used: (1) the laboratory experiments were used to define some correlation-based models, and (2) these models
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
were converted to prototype conditions. A number of correlation-based models predicting the volumetric displacement flow
rate Vinf,p (L/s) in terms of different variables (e.g., Np, θx) for different seal conditions were developed for revolving doors. Those with the highest R2 are presented below. In the case of prototype revolving door with all seals of good quality, the following correlation-based model is selected, with R2 of 0.81, standard error of 0.075 L/s and relative error of 18.6%:
20
Page 20 of 40
Vinf,p = (0.64·Np2 - 1.72·Np - 19.62·θAh - 0.46·θAl - 8.45·θBh + 3.53·θBl – 1.55·θCh -5.27·θCl - 6.13·θDh + 3.08·θDl + 22.19·θMo + 10.85·θMi + 9.34)/ρ
ip t
(17)
cr
In the case of prototype revolving door without any vertical seals, as an extreme
us
case, the following correlation-based model is selected, with R2 of 0.99, standard error of 0.069 L/s and relative error of 6.9%:
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Vinf,p = (2.62·Np2 - 7.08·Np - 83.18·θAh - 43.57·θAl - 85.63·θBh + 11.64·θBl + 142.97·θCh + 119.52·θCl - 130.84·θDh + 245.69·θDl + 12.35·θMo - 164.46·θMi -
M
95.82)/ρ
(18)
d
Therefore, the air infiltration rate through an existing revolving door can be
te
evaluated from site measurements of the rotation speed (Np) and air temperature at some selected points (Figure 3).
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
4. Conclusions
The results of reduced-scale experiments show that the air displacement flow
rate due to the motion of revolving door increases only slightly with the rotation speed and has a small contribution to the total air infiltration rate, contrary to the previous data obtained some 50 years ago. For the conditions of this study, the air displaced rate is about two orders of magnitude less than the values currently used in the calculation of air infiltration rate. 21
Page 21 of 40
The air infiltration due to the revolution of the door should be included in the provisions of standards and by-laws to help designers for proper estimation of heating loads.
ip t
The correlation-based models developed in this study are proposed to be used, along with the site measurements of the rotation speed and air temperature at some
cr
selected points, for the on-site estimation of the air displacement rates of existing
us
revolving doors.
Future work in laboratory set-up will include models of other scales to evaluate
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for instance the effect of scale and the influence of buoyancy forces. Other measurement techniques will be tested, such as depressurization with blower door,
Acknowledgments
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on-site on existing revolving doors.
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The authors acknowledge the financial support from Natural Sciences and Engineering Research Council of Canada and from Faculty of Engineering and Computer
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Science of Concordia University.
References [1]
Stalder L. Turning architecture inside out: Revolving doors and other threshold devices. Journal of Design History 2009; 22(1): 69-77.
[2]
Schutrum LF, Ozisik N, Baker JT, Humphreys CM. Air infiltration through revolving doors. ASHRAE Journal 1961; 3(11): 43-50.
22
Page 22 of 40
[3]
ASHRAE. ANSI/ASHRAE/IESNA Standard 90.1. Energy Standard for Buildings Except Low-Rise Residential Buildings. American Society of Heating, Refrigerating and Air-conditioning Engineers, Inc., Atlanta, GA; 2010.
[4]
McQuiston FC, Spitler JD. Cooling and heating load calculation manual, 2nd ed.
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American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA; 1992.
Zmeureanu R, Stathopoulos T, Schopmeijer MED, Siret F, Payer, J. Measurements
cr
[5]
us
of air leakage through revolving doors of institutional building. ASCE: Journal of Architectural Engineering 2001; 7(4): 131-137. [6]
ASHRAE. ASHRAE standard 90.1. American Society of Heating, Refrigerating
[7]
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and Air-conditioning Engineers, Inc., Atlanta, GA; 1989.
MNECCB. Model national energy code of Canada for buildings. National Research
[8]
M
Council Canada (NRCC), Ottawa; 1997.
Allgayer DM, Hunt GR. Air movement by revolving doors. Proceedings of
d
Roomvent 2004. Eighth International Conference on Air Distribution in Rooms,
[9]
te
Coimbra, Portugal; 2004.
Alggayer DM, Hunt GR. Hybrid ventilation by revolving doors. Proceedings of Healthy Buildings 2006, Vol. IV, 21-220, Lisboa, Portugal.
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[10] Allgayer, D. Air and heat movement by revolving doors. LAP LAMBERT Academic Publishing GmbH & Co. KG.
[11] Cullum BA, Lee O, Sukkasi S, Wesolowski D. Modifying habits towards sustainability: A study of revolving door usage on the MIT campus. http://web.mit.edu/wesolows/www/11.366_REVOLVING_DOOR_FINAL_REPORT.pdf,
Cambridge, MA. [Accessed July 2008] [12] Min TC. Winter infiltration through swinging-door entrances in multistory buildings. ASHRAE Transactions; 64, 421. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc, Atlanta, GA; 1958.
23
Page 23 of 40
[13] McGowan A, Jutras R, Riopel G, Hanam M. Heat transfer through roll-up doors, revolving doors and opaque nonresidential swinging, sliding and rolling doors. ASHRAE Research project 1236-RP. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA; 2006.
Fenestration Rating Council, Silver Spring, MD; 2004.
ip t
[14] NFRC 400. Procedure for determining fenestration product air leakage. National
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[15] Energy conservation building code 2006. International Institute for Energy
us
Conservation, U.S; 2006.
[16] Fox RW, McDonald AT. Introduction to fluid mechanics, 5th ed. John Wiley &
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Sons, Inc. New York; 1998.
[17] Halliday D, Resnick R, Walker J. Fundamentals of physics, 8th ed. Wiley:
M
Hoboken, NJ; 2001.
[18] Bérubé Dufour M, Derome D, Tardif M, Zmeureanu R. Measurement of air temperature using infrared thermography in rooms equipped with displacement
d
ventilation in cold climate. Proceedings of the 8th Nordic Symposium on Building
te
Physics, Copenhagen, June; 2008.
[19] Elektror airsystems gmbh. Elektror catalog medium pressure blower. http://pdf.directindustry.com/pdf/elektror/product-review-24355-
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
7697.html#pdf_7697 [Accessed February 2013].
[20] Aupied A. Measurements, Calculations, Highlights and Visualization of the Heat Loss in a Building Caused by the Rotation of a Revolving Door. Internal report. Concordia University, Montreal; 2009.
24
Page 24 of 40
List of Figure Captions
LIST OF FIGURES Figure 1. Dimensions of the experimental box and revolving door without outside insulation
Figure 2. Experimental setup
cr
Figure 3. Temperature measurement points around the revolving door
ip t
(dimensions in cm)
us
Figure 4. Additional thermocouples outside the door to identify the air flow direction (dimensions in cm)
an
Figure 5. Average rotation speed of revolving doors for different traffic rates measured Figure 6. Volumetric air infiltration rate evaluated for different rotation speeds of the
M
experimental revolving door
Fig. 7. Infrared image on a horizontal screen outside of the revolving door with four seals at N m=
d
50 rpm
300 rpm
te
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at N m=
Ac ce p
Figure 9. Comparison of experimental air infiltration rates due to the revolution of a door at different rotation speeds
Figure 10. Effect of different conditions of seals on the air infiltration rates of revolving doors Figure 11. Dimensionless temperature at thermocouple locations A, B, C, and D around the experimental revolving door
Figure 12. Air temperature distribution outside the door at low rotation speed (Nm = 173 rpm) Figure 13. Air temperature distribution outside the door at high rotation speed (Nm = 296 rpm)
1
Page 25 of 40
Ac ce p
te
d
M
an
us
cr
ip t
Figure(s)
Fig. 1. Dimensions of the experimental box and revolving door without outside insulation (dimensions in mm)
1
Page 26 of 40
T
ip t T
FAN
T
us
T T
cr
HEATER
T
T
T
MOTOR
an
T
Insulation
M
T T T
VARIABLE AUTOTRASFORMER
T
d
POWER SUPPLY
Ac ce p
te
DATA ACQUISITION SYSTEM (DAS)
Fig 2. Experimental setup
2
Page 27 of 40
ip t cr
an
Mi Bh Bl
M
Ch Cl
Dh Dl
us
Ti
Mo
Ah Al
Ac ce p
te
d
To
Fig. 3. Temperature measurement points around the revolving door
3
Page 28 of 40
ip t cr us an M d te Ac ce p
Fig 4. Additional thermocouples outside the door to identify the air flow direction (dimensions in mm)
.
4
Page 29 of 40
ip t cr
8
us
6 5
R² = 0.8918
4
an
Average N (rpm)
7
3 2
0 0
200
M
1 400
from Schutrum et al. (1961) field studies
600
800
1000
1200
te
d
Persons per hour
Ac ce p
Fig. 5. Average rotation speed of revolving doors for different traffic rates measured
5
Page 30 of 40
ip t
0.60
25℃
0.50
40℃
cr
16-21℃
0.70
us
0.40 0.30 0.20 0.10 0.00 0
100
an
Air infiltration rate (L/s)
0.80
200
300
400
M
Experimental rotation speed (rpm)
d
Fig. 6. Volumetric air infiltration rate evaluated for different rotation speeds of the
Ac ce p
te
experimental revolving door
6
Page 31 of 40
ip t cr us an M
Ac ce p
te
d
Fig. 7. Infrared image on a horizontal screen outside of the revolving door with four seals at Nm= 50 rpm
7
Page 32 of 40
ip t cr us an M
Ac ce p
te
d
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at Nm= 300 rpm
8
Page 33 of 40
ip t
100.0
10.0
us
cr
Centrifugal fan with diameter of 21 cm
1.0
an
lg(Air flow rate) (L/s)
Schutrum et al. (1961)
Experimental results from this research
0.1 0
100
200
300
400
500
d
M
Experimental rotation speed (rpm)
te
Fig. 9. Comparison of experimental air infiltration rates due to the revolution of a door at
Ac ce p
different rotation speeds
9
Page 34 of 40
ip t cr
1.20
Without vertical seals
1.00
us
0.80
With two wings having seals
0.60 0.40
an
Experimental air infiltration rate (L/s)
1.40
With full seal condition
0.20 0.00
100 200 300 400 Experimental rotation speed (rpm))
500
d
M
0
doors
Ac ce p
te
Fig. 10. Effect of different conditions of seals on the air infiltration rates of revolving
10
Page 35 of 40
ip t
R² = 0.8789
A
cr
0.80
B
R² = 0.3842
0.60 0.40
R² = 0.8839
0.20
us
C
an
Dimensionless temperature
1.00
Ti
D
Ch Cl
Mi
Dh Dl
Mo
Bh Bl
R² = 0.6971
0.00
100 200 300 Experimental rotation speed (rpm)
400
Ah Al To
te
d
M
0
Fig. 11. Dimensionless temperature at thermocouple locations A, B, C, and D around
Ac ce p
the experimental revolving door
11
Page 36 of 40
ip t cr 6.31 (0.34) 3.99 (0.21) 2.74 (0.15)
an
To (°C) 6.34 (0.34) (θx)
Door holder
us
Ti – To = 18.5 °C Nm = 173 rpm
3.12 (0.17)
6.34 (0.34) 2.92 (0.16)
3.98 (0.22) 3.17 (0.17)
Ac ce p
te
d
M
2.92 (0.16)
4.95 (0.27)
Fig. 12. Air temperature distribution outside the door at low rotation speed (Nm = 173 rpm)
12
Page 37 of 40
3.84 (0.27) 1.63 (0.12)
M
1.90 (0.14) 1.76 (0.13)
us
cr
ip t 3.26 (0.23)
4.67 (0.33) 3.53 (0.25) 1.67 (0.12)
Door holder
4.07 (0.29) 2.89 (0.21) 1.23 (0.09)
Ac ce p
te
d
To (°C) (θx)
an
Ti – To = 14 °C Nm = 296 rpm
Fig. 13. Air temperature distribution outside the door at high rotation speed (Nm = 296 rpm)
13
Page 38 of 40
Outdoor
Indoor
Ac ce p
te
d
M
an
us
cr
ip t
Graphical Abstract (for review)
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at Nmodel = 300 rpm
1
Page 39 of 40
*Highlights (for review)
Highlights We present results from a reduced-scale physical model of revolving door Air displaced by door rotation is two orders of magnitude inferior to previous data
ip t
Increasing the door rotation speed does not increase significantly the air displaced
Ac ce p
te
d
M
an
us
cr
Correlation-based models to be used for on-site estimation of the air displacement
Page 40 of 40
S0378-7788(13)00748-2 http://dx.doi.org/doi:10.1016/j.enbuild.2013.11.041 ENB 4642
To appear in:
ENB
Received date: Revised date: Accepted date:
26-2-2013 4-11-2013 9-11-2013
Please cite this article as: L. Du, R. Zmeureanu, T. Stathopoulos, An empirical model of air displacement by revolving doors, Energy and Buildings (2013), http://dx.doi.org/10.1016/j.enbuild.2013.11.041 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
*Manuscript
An empirical model of air displacement by revolving doors Lin Du, Radu Zmeureanu* and Ted Stathopoulos Centre for Zero Energy Building Studies, Department of Building, Civil and
cr
Montreal, Quebec, CANADA H3G 1M8
ip t
Environmental Engineering, Concordia University,
*
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Corresponding author; Phone: 1-514-848-2424/3203 Email: [email protected]
an
Abstract
This paper presents an experimental study on a reduced scale model to quantify
M
the air displacement due to the revolution of revolving doors. The results show that the
d
air displaced by revolving doors increases only slightly with the rotation speed, and is
te
about two orders of magnitude less than values currently used in the calculation of air infiltration rate, for the same conditions. The correlation-based models developed in this study from experimental data are proposed to be used for the estimation of the air
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
infiltration rates of existing revolving doors that are installed in large commercial or institutional buildings.
Keywords: Air infiltration, Revolving door, Measurements, Reduced-scale model
1
Page 1 of 40
1.
Introduction
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Revolving doors are widely used as entrances of large public buildings such as office buildings, shopping malls and hotels, which have high traffic of people. This four-
cr
wing revolving door type keeps the entrance closed all the time to reduce the air
infiltration and hence minimizes the energy needs for heating caused by the entrance [1].
us
The air exchange through a revolving door can be calculated as the sum of (1) the air
an
leakage through the gaps and seals between the wings and the door housing, due to the pressure difference across the door, caused by stack and wind effects; and (2) the air
M
displacement due to the revolution of the door, evaluated in terms of door rotation speed and temperature difference between indoor and outdoor environments.
d
Schutrum et al. [2] measured the air exchange on a full-scale revolving door
te
installed at the entrance of a laboratory using a tracer gas technique with hydrogen. The hydrogen concentration was measured with a cathetometer, which detected changes in the
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
thermal conductivity of mixture air-gas, due to the presence of hydrogen. The measurements were made with two sets of new seals and one set of worn seals, which still had a good contact with the door housing. The results reveal that at the stationary condition the air infiltration through door seals depends on the condition of seals, the wing position and the indoor-outdoor pressure difference. When the door rotates, the air infiltration of a motor-operated revolving door is presented as a function of inside-outside temperature difference and rotation speed. The infiltration of the manually-operated revolving doors was presented in terms of rotation speed, inside-outside temperature difference, outside wind velocity and indoor air movement. 2
Page 2 of 40
ASHRAE Standard 90.1 [3] and Load Calculation Manual [4] recommended the estimation of heating load due to cold air infiltration through revolving doors of commercial or institutional buildings based on reference [2] when measurements from
ip t
manufacturers are not available.
Zmeureanu et al.[5] measured the air infiltration through gaps and seals of four
cr
revolving doors of a university building, at stationary conditions, by using the blower
us
door technique. The air infiltration rate of those doors were compared with
recommendations from ASHRAE Standard 90.1 [6] and the MNECCB [7], as well as
an
with the air infiltration rate of a new revolving door tested by an independent consultant at a manufacturer’s facility. The leakage rates for all four doors greatly exceeded the
M
values specified by both standards as well as the results from [2]. Those doors have been
d
in operation for more than 30 years and the seals lack of maintenance, while the door
te
used by [2] was installed properly for the experimental purposes. In the same study we also evaluated the impact of door rotation speed on the air infiltration rate. In the case of the door with seals of acceptable quality, the air flow rate
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
through the door did not change compared with the case of not revolving door. Hence, the air displaced by the revolving door was negligible. In the case of two doors, which have only three vertical seals, the data acquisition system was not able to collect reliable data because of large fluctuations of the pressure differential across the doors. Air flow through a revolving door when it rotates was examined in a water chamber by Allgayer and Hunt [8-9] using a scaled model approximately 1/10th of the full size. A transparent tank was partitioned into two compartments and a rectangular opening in the partition housed the revolving door. The fresh and salt-water solution, which produced 3
Page 3 of 40
the density difference, was used to represent temperature difference through the doorway. The experiment focused on the flow pattern and the effect of the door rotation rate and temperature difference across the doorway. It was concluded from the experimental
ip t
results that when the rotation speed exceeds a critical rotation rate, at same indoor-
outdoor temperature difference, the exchange rate becomes independent of the rotation
cr
speed and it remains constant. This regime is called buoyancy-limited-constant. For
us
rotation rates lower than the critical value, which occurs in the revolution-limited regime, the air exchange increases with the rotation speed. If the rotation rate exceeds the
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maximum value of the buoyancy-limited-constant regime, the air exchange decreases. Allgayer [10] presented the theoretical and technical description of the scaled modeling
M
technique, the results and a set of design charts to estimate the air exchange in terms of
d
revolution rate and external temperature.
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Cullum et al. [11] estimated the annual energy consumption for heating/cooling of a building on the MIT campus. The graphs of Schutrum et al. [2] were used to estimate the air infiltrated through revolving doors, and the graphs of Min [12] were used for
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
swinging doors. The amount of energy found was near 100.000 kWh. This seems to be over-estimated as it is enough to heat 6.5 single-family houses in one year, or to light a 100 W bulb for 37.8 years. Perhaps this is due to the use of over-estimated air infiltration rates from [2].
The ASHRAE Research Project 1236-RP [13] evaluated the U-value of several non-residential door products, including a four-wing revolving door; the U-value obtained by 2D CFD modeling was about 3.6 W/(m2·°C) while the measured value was 3.48 W/(m2·°C). The air leakage when the door was not revolving was measured based 4
Page 4 of 40
on the NFRC 400 [14]; when all four wings were in contact with the curved sidewalls, the air leakage was 8.9 L/(s·m2) at 75 Pa pressure difference. The case of door revolving was not, however, among the project objectives.
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The ASHRAE standard 90.1 [3] and the Energy Conservation Building Code 2006 [15] specified that the air leakage for commercial entrance (swinging or revolving doors)
cr
shall not exceed 5.0 L/(s·m2 of the door area) when tested at 75 Pa pressure difference.
us
The MNECCB [7] specified that air leakage rate through swinging, revolving and sliding doors should not be more than 17 L/s for each meter of the door crack, which is
an
equivalent to 68.0 L/(s·m2 of the door area). These standards are vague about the conditions of the application of the recommended values. It can be assumed that, for
M
swinging and sliding doors, the recommendations are made for closed doors. However, it
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turn.
d
is not clear whether the values should apply when revolving doors are still or when they
The inconsistencies found in the previously mentioned studies on air infiltration due to the movement of revolving doors, and the need for new information for the analysis
Ac ce p
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and improvement of the provisions of standards or by-laws prescriptions and to increase the accuracy of estimations of heating loads and energy use, were the principal forces to carry out the present experimental study. The two components of air infiltration through a revolving door, that is the air
leakage and air displacement, might occur simultaneously, for instance when a door with worn seals is in motion. The air leakage through the gaps and seals of an existing door can be easily measured by using, for instance, the blower door technique, while the air displacement is more difficult to measure in-situ. For this reason, this study focused only 5
Page 5 of 40
on the evaluation of the air displaced by the door rotation. The measurements from a reduced-scale physical model were used along with the heat balance method to estimate the air displacement due to the door rotation. Some correlation-based models were first
ip t
developed for the reduced-scale physical model, and then these models were converted to
Methodology
us
2.
cr
prototype conditions to allow for the in-situ estimation of air displacement.
A reduced-scale physical model was manufactured to simulate a revolving door in
an
the Energy Efficiency laboratory of Concordia University. An airtight box with a reduced-scale revolving door on the front side (Fig. 1) was installed in a climatic
M
chamber in which the temperature was kept between 0.5°C and 2°C. The reduced scale
d
four-wing revolving door was made of Plexiglass of 5 mm thickness, with a vertical
te
squared shaft of 14 mm width, on which the four wings were connected. The seals of 5 mm thickness, made of a brush-type gasket, were installed on the top and bottom of each wing as well on the vertical side, pressing on the door housing. An electric motor was
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installed on top of the vertical shaft to control the door rotation speed. The box represented the hall of a building, and the climatic chamber (3.65 m × 2.45
m × 2.03 m) represented the outdoor environment. Inside the box there was a heater to control the air temperature (e.g., around 20°C), and a small fan of 0.4 W, which circulated the indoor air to create a uniform temperature distribution. In order to reduce the heat losses through the box walls, two layers of expanded styrofoam of 0.05 m thickness each were mounted on the outside surface of the box. One layer of aluminum
6
Page 6 of 40
paper was taped on the outside surface of insulation to reduce the heat exchange by radiation between the box and environmental chamber. The net air flow rate, which was only due to the rotation of revolving door, was
ip t
calculated from the heat balance equation applied to the air inside the box, by using
measurements of air temperatures inside and outside the box, and the electric power input
cr
to the heater and fan installed in the box. The direction of air flow leaving the revolving
us
door was also determined from measurements of air temperature and visualized by
2.1
Reduced-scale physical model
an
infrared thermography.
M
The prototype and the physical model must be similar in terms of linear dimensions,
d
shape, and airflow pattern [16]. Only when the independent dimensionless groups are the
te
same in scaled-model and prototype, the relationships between scaled model and fullscale prototype are correct.
The model used in this experiment was a 1/10 scaled model, so the geometric scale
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ratio λL was:
Dp L
Dm
10
(1)
where: D = diameter of the revolving door; the subscript “p” refers to the prototype (real life) dimension; Dp =2.10 m, and “m” refers to the reduced scale model; Dm =0.21 m. The door height is Hm = 0.21 m. The scaled and prototype models had the same Reynolds (Re) number, of about 2900, which was defined in terms of angular speed ω, in rad, and the diameter of the 7
Page 7 of 40
revolving door D [17]. Since the air was used as fluid in both model and prototype, the kinematic viscosity is equal, and therefore the angular velocity factor λω was written as
p
(
1 100
(2)
cr
m
Dm 2 ) Dp
ip t
follows:
V
Vm
3 p Dp 3 m Dm
1 10 3 10 100
where: V = volumetric flow rate, in L/s.
(3)
an
Vp
us
The fan law [15] was used to define the air flow factor λV as follows:
M
The air leakage was eliminated by installing good horizontal and vertical seals on each wing. The only air exchange between outdoor and indoor environments was due to
d
the rotation of revolving door. Under these conditions, there was no gravity force, and
te
therefore the similarity of Froude number was not required.
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2.2
Measurements
A Data Acquisition System (DAS) type 34970 (Agilent) was used for collecting
the measured data and controlling the revolving speed (Fig. 2). Two modules with 20 channels on each to record temperature and electrical current, and one multifunction module to record the total number of rotations of the door were installed in the DAS unit. The voltage and current signals for the heater were recorded by the DAS.
8
Page 8 of 40
There were four groups of thermocouples (T type, special limit), indicated in Figure 3 as A, B, C, and D, installed outside and inside, very close to the door to measure the temperature of air moved by the turning segments. All the small “T”s in circle (Fig. 2)
ip t
represent the location of thermocouples. The “h” subscript indicates a higher location of thermocouples (at 0.25·Hm from the door top), and the “l” subscript indicates a lower
cr
thermocouple (at 0.25·Hm from the door bottom). There are also two thermocouples, Mo
us
and Mi, at the middle height and center near the revolving door. Mo is the thermocouple
an
installed outside and Mi is the thermocouple installed inside the box. The fan and the door motor shared one power supply system, and their voltages and
M
currents were recorded by the DAS as well. The DAS not only reads the voltage input to the motor, but can also control the revolving door speed. The rotation speed was
d
measured as well.
te
In addition to those thermocouples, ten thermocouples were installed in several experiments in a horizontal plan in the front center outside the revolving door to identify
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the air temperature distribution that can give an indication about the direction of air movement, generated by the revolving door (Fig. 4). To visualize the air flow direction when it leaves the revolving door, a mosquito
screen fixed on a frame was placed in horizontal position outside the revolving door. The screen temperature, which is influenced by the warmer air flow coming out from the box, was measured with an infrared camera using the technique explained in [18].
2.3 Heat balance equation 9
Page 9 of 40
The air mass flow rate brought in the box when the door rotates is calculated from the heat balance equation applied to the air inside the box over the time interval Δt: Q fan
Qloss
(4)
Qdoor
where: ΔQ = energy change inside the experimental box in J;
cr
Qheater = heat generated by the heater, in J;
us
Qfan = heat generated by the small fan, in J; Qloss = heat loss through the box walls, in J;
ip t
Q Qheater
an
Qdoor = heat loss due to the cold air brought in the box when the door rotates, in J. The electric motor driving the door was installed outside the box, and therefore the
M
electric power input did not affect the heat balance inside the box. The electric power input to small fan installed inside the box was converted entirely into heat.
te
d
The following equations apply: Q m2 c p T2
m1 c p T1
(
2
T2
1
T1 ) c p Vbox
(5)
where: ρ1 = air density at the beginning of the time interval Δt;
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ρ2 = air density at the end of the time interval Δt; T1 = initial temperature inside the box at the beginning of the time interval Δt; T2 = final temperature inside the box at the end of the time interval Δt; cp = specific heat of air, in J/(kg·°C); and Vbox = internal volume of the box = 0.146 m3. Qheater = Δtstep·
Vheater, j I heater, j
(6)
j
10
Page 10 of 40
where: Δtstep = time step between each recording j, equal to 10 s; Vheater = electrical potential difference (voltage) applied to heater, in V;
Qfan = Δtstep·
ip t
Iheater = electric current for heater, in A; V fan, j I fan, j
(7)
cr
j
where: Vfan = electrical potential difference (voltage) applied to the fan, in V;
t step
(Ti
To ) j
(8)
an
Qloss U A
us
Ifan = electric current for fan, in A;
j
M
where: U = overall heat transfer coefficient, in W/(m2·K);
A = exterior surface area of the experimental box, in m2;
d
Ti = average indoor air temperature of the box, in °C;
te
To = average air temperature of the environmental chamber, in °C; Qdoor
Ac ce p
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minf,m c p
t step
(Ti
To ) j
(9)
j
where: minf,m = air mass flow rate, in kg/s, due to the motion of reduced-scale revolving door.
The air volumetric flow rate through the revolving door Vinf,m (L/s) is:
Vinf,m 1000
minf,m
(10)
where: ρ = air density at 1°C (the average temperature in the environmental chamber) and atmospheric pressure = 1.29 kg/m3 [15]. The air temperature inside the box was kept constant at different set point values between 16 and 40°C, and the air outside the box 11
Page 11 of 40
was between 0.5 and 2°C. A constant average value of 1.005 J/(kg·°C) for the specific heat was used in calculations, as the impact of air temperature is negligible within the
3.1
Rotation speed
cr
Experimental results and discussion
us
3.
ip t
range of variation; the error is about 0.3%.
an
Prior to the experimental measurements, in order to define the range of rotation speeds of revolving the doors, field observations were made on one office building and
M
two university buildings. The number of people passing through the revolving doors and the number of rotations in each five-minute interval were recorded for several hours for
d
each building. Data collected were converted to the traffic rate, in persons per hour, and
te
the average rotation speed Np in rotations per minute (rpm). The rotation speed of revolving doors in the field studies varied from 0.8 to 6.2 rpm. At the same traffic flow
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rate, the average rotation speed observed in this study (Fig. 5) is lower than that presented by [2]. It should be noted, however, that the present study included the idle time, while data from [2] excluded the idle time. Since the purpose of visual investigation carried out at the beginning of this study was only to identify a reasonable range of rotation speed, the difference between two experimental results would have no impact on the results of this study. In the reduced-scale model, the experiments were carried out at different rotation speeds Nm ranging from 19 to 370 rpm, corresponding to 0.19 to 3.7 rpm in the prototype
12
Page 12 of 40
doors. Higher rotation speeds were not attempted because of concerns about the physical robustness of the rotation mechanism.
U·A-value
ip t
3.2
cr
The overall U·A-value, used in Equation 8, was calculated from the heat balance
the door not moving:
U A
V fan I fan ) j
an
(Vheater I heater j
us
equation of air inside the box by using preliminary results at steady-state conditions with
(Ti
(11)
To ) j
j
M
The calculated UA value was between 0.72 and 1.26 W/(m2·K) including the convection on the inside surfaces that was generated by the small fan that runs
d
continuously. When the door rotates, the air movement increases the convective
te
coefficient on inside surfaces above that value. The air displacement rate calculated from measurements was therefore a conservative high value, as the increase of UA value
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would lead to a smaller estimated air displacement. The following relationship between the overall U·A-value, in W/K, and the indoor temperature Ti from about 15.5°C to 43.3°C, at To from 0.5°C to 2°C, was obtained by using the least-squares method, with the coefficient of determination R2 = 0.96: U·A = 0.4181 + 0.0197·Ti
3.3
(12)
Air displacement rate in the reduced-scale model
13
Page 13 of 40
Figure 6 shows the volumetric air displacement rate in the reduced-scale model, under different rotation speeds and indoor temperatures, at outdoor air temperature To ranging from 0.5°C to 2°C. The results at indoor temperature of 40°C are within the same
ip t
range of the results as experiments around 20°C, including the limited measurements at 25°C. Hence, the results from this study are not affected by the air temperature difference
cr
within the limits of this study. By linear regression on the data shown in Figure 6, the
us
volumetric air displacement rate Vinf,m, in L/s, through the reduced-scale revolving door is expressed as function of the rotation speed Nm of the reduced-scale model, in rpm, as
an
follows:
(13)
M
Vinf,m = 0.0006·Nm + 0.2148
The regression model shows that the air displacement rate is not sensitive to the
d
rotation speed of revolving door, within the limits used in this study. The coefficient of
te
determination R2 = 0.51, due to the dispersion of experimental points around the trend line, indicates that other variables, not identified in this study, have an impact on the air
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displacement rate in addition to the door rotation speed. Such variables could be the density difference between the cold and warm air, the temperature gradient inside the box, and the increase of UA value.
By using dimensionless criteria presented in section 2.1 along with Equation 13,
the volumetric air displacement rate Vinf,p, in L/s, in the prototype door is expressed as a function of the rotation speed Np, in rpm, as follows: Vinf,p = 0.6·Np + 2.15 3.4
(14)
Infrared visualization 14
Page 14 of 40
To visualize the air flow direction when it leaves the revolving door, the infrared thermography was used, and infrared images were recorded at different rotation speeds and with different conditions of seals – with full seals around the wings and with no
ip t
vertical seals on the side of wings. A mosquito screen fixed on a frame was placed in horizontal position outside of the revolving door, at mid-height of the door. The infrared
cr
camera was placed above the screen. The air flow coming from indoor environment
us
results in different temperature distribution on the net and this temperature difference can be shown by the colorful infrared pictures. In these images, the more reddish color
an
represents higher temperature and the more bluish color represents lower temperature. Figures 7 and 8 show the infrared images when the door has seals around the four wings,
M
and the rotation speed of 50 and 300 rpm, respectively. The door rotates
d
counterclockwise. The infrared images show that the warm air brought from inside by the
te
door movement is pushed towards the door housing. The area of expansion of warm air is very narrow near the door, as a result of air being re-absorbed inside the door, when the door bay closes. The same trend is expected to occur near the door inside the box, when
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the colder air enters the box. Therefore the air displaced by the door rotation has a small impact of the heat balance of the box interior, which leads to the estimation of low air displacement rate. 3.5
Error analysis
The measured physical quantities are: voltage and current inputs to the heater and fan installed inside the box; dimension of the box; air temperature; and time. The measurement error of DC voltage is ±0.004% for the small fan and of AC voltage is 15
Page 15 of 40
±0.06% for the heater. The 0.1Ω electricity resistance installed in the circuits has a relative error of ±1%. The bias uncertainty of thermocouples reading, from Siemens Building Technologies, is 0.005·T+0.3 that gives the uncertainty of 0.4°C, or a relative
ip t
uncertainty of about 2%. The propagated uncertainty of calculated air infiltration rate, based on measurements, is between 0.023 and 0.050 L/s, or the relative uncertainty is
us
3.6
cr
between 5 and 22%. Discussion
an
The volumetric air infiltration rates at different rotation speeds measured in this study are smaller than the results from [2]. Further discussion is necessary since there is
M
no other publication available for the comparison of the air flow rate caused by rotation of the door.
d
The first comparison is made between the air flow rate supplied by a centrifugal
te
fan and the air flow rate pushed in the building by a revolving door, as they may have similar air dynamics. The performance data of a centrifugal fan with the same dimensions
Ac ce p
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as the reduced-scale revolving door is selected from a manufacturer’s catalogue [19] for this comparison. This is a centrifugal fan with diameter of 0.204 m that gives an air flow rate of 45 L/s at 2920 rpm. Based on the fan law [16], the air flow rate at other rotation speeds is calculated as follows:
V2
V1
D23 D13
2 1
0.0168
2
(15)
Figure 9 compares the air infiltration rate from (1) the reduced-scale model, (2) the centrifugal fan, and (3) from [2] converted at the reduced-scale dimensions. The values presented by [2], for 10-15°C temperature difference and at several rotation speeds, range 16
Page 16 of 40
from 10 to 29 L/s, suggesting that a revolving door pushes much more air inside a building than a centrifugal fan of the same size and rotation speed, with corresponding values from 0.3 to 6.2 L/s. This is impossible! The results of this study, with values from
ip t
0.25 to 0.48 L/s, are much lower than those of centrifugal fan, as expected. This relative comparison shows that the results from this study show that the air displaced by
cr
revolving doors is about two orders of magnitude less than values currently used in the
us
calculation of air infiltration rate based on [2].
an
A second comparison is made between the annual energy use for heating the cold air infiltrating due to the rotation of a revolving door according to data from [2] and data
M
from present study. The calculations were carried out by using the degree-day method. The rotating door was assumed to be located in Montreal, where the design outdoor air
d
temperature for heating is -23°C and the number of heating degree-days is about 4500ºC.
te
For the indoor air temperature of 18°C, the electric demand for heating only the cold air displaced into the building by the revolving door is about 13 kW based on [2]. The
Ac ce p
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corresponding annual heating energy usage is estimated at 23,600 kWh, which equals the average annual energy consumption of a house in Montreal. This shows that the air infiltration rate from [2] is overestimated. However, if data from present study were used, the electric heater for the same case has a capacity of only 0.2 kW and the annual energy consumption is about 300 kWh. Therefore, we consider more credible the experimental data from this study. When the results from the reduced-scale model are converted to prototype doors, at rotation speeds between 0.2 rpm and 3.6 rpm, the air infiltration caused by the rotation of a door with good seals varies from 2.3 L/s to 4.4 L/s. These values 17
Page 17 of 40
correspond to 0.5-1.0 L/s·m2 of the door area or 10-20% of maximum values given in [3, 15]. The recommended limitation of the air infiltration through revolving doors, as presented in some standards, is most likely only for the part of air infiltration
ip t
through gaps and seals when revolving doors do not move. The air displacement due
cr
to the revolution of the door should also be included in those standards.
us
3.7 Air displacement through revolving doors with different conditions of seals The results presented in section 3.3 are for a reduced-scale revolving door having all
an
four wings with seals of good quality in contact with the door housing. Figure 10
M
compares those results with those obtained with the same experimental setup from (1) one door without two vertical seals, and (2) another door without any vertical seals [20].
d
As expected, the air displacement rate due to the door revolution increases when the
te
seals are removed, particularly at high rotation speeds. This is an extreme case of seals without proper maintenance or replacement. The results underline the importance of
Ac ce p
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maintaining the seals’ quality around the wings for reducing the air infiltration and, therefore, the energy use for heating.
3.8
Dimensionless air temperature
To normalize the results for different indoor and outdoor temperatures, which
slightly varied from one experiment to another, the dimensionless air temperature θx is calculated at each selected location x near the door opening (Fig. 3) when the door rotates:
18
Page 18 of 40
x
Tx To Ti To
(16)
where Tx = temperature at location x, in °C. Each temperature is the average value over
ip t
the last five minutes of the recording period. The revolving door is turning counterclockwise. For each group A, B, C and D, the dimensionless temperature is
cr
calculated using the average value of the “h” and “l” test points (see Fig. 3). The “h”
us
subscript represents a higher thermocouple, and the “l” subscript represents a lower thermocouple.
an
Figure 11 shows that the dimensionless temperatures θB and θC (inside the box) are higher than θA and θD (outside the box). When the rotation speed is greater than about
M
100 rpm, θC remains constant at about 0.75. This is another indication that the cold air displaced by the revolving door does not increase with the increase of rotation speed.
te
d
Since θB > θC regardless of the rotation speed, the thermocouple installed at location C is more affected than at point B by the cold air brought inside the box by the revolving door; hence the displacement air is mostly directed towards location C.
Ac ce p
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The measurements from the additional thermocouples installed outside the
revolving door in the horizontal plan were also used to identify the direction of air flow leaving the revolving door. Figures 12 and 13 show the air temperature distribution outside the door at the rotation speeds of 173 and 296 rpm, respectively, both at the indoor air temperature of 20°C. The values presented are the average air temperature Tx, in °C, of last five minutes of the measurement period. The dimensionless temperature θx is also presented within brackets. In all cases, when the door rotates counterclockwise,
19
Page 19 of 40
the air is pushed along the tangent to the door housing. Figure 12 suggests that a proportion of air pushed by the revolving door re-enters the door segment. The results presented in this section are supported by the infrared thermography
ip t
(section 3.4) that the air brought in by the door rotation is mostly re-absorbed inside the
3.9
us
cr
door, when the door bay closes.
Measurement of air infiltration through existing revolving doors
an
It is difficult to use the same approach as in the laboratory to measure the air displacement rate through an existing revolving door in a large building. It would be
M
more practical if the air displacement rate can be estimated based on some site measurements of variables with significant impact such as rotation speed N of revolving
te
d
door and air temperature at several locations near the door (e.g., at A, B, C and D locations in Figure 3). Therefore a two-step approach was used: (1) the laboratory experiments were used to define some correlation-based models, and (2) these models
Ac ce p
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were converted to prototype conditions. A number of correlation-based models predicting the volumetric displacement flow
rate Vinf,p (L/s) in terms of different variables (e.g., Np, θx) for different seal conditions were developed for revolving doors. Those with the highest R2 are presented below. In the case of prototype revolving door with all seals of good quality, the following correlation-based model is selected, with R2 of 0.81, standard error of 0.075 L/s and relative error of 18.6%:
20
Page 20 of 40
Vinf,p = (0.64·Np2 - 1.72·Np - 19.62·θAh - 0.46·θAl - 8.45·θBh + 3.53·θBl – 1.55·θCh -5.27·θCl - 6.13·θDh + 3.08·θDl + 22.19·θMo + 10.85·θMi + 9.34)/ρ
ip t
(17)
cr
In the case of prototype revolving door without any vertical seals, as an extreme
us
case, the following correlation-based model is selected, with R2 of 0.99, standard error of 0.069 L/s and relative error of 6.9%:
an
Vinf,p = (2.62·Np2 - 7.08·Np - 83.18·θAh - 43.57·θAl - 85.63·θBh + 11.64·θBl + 142.97·θCh + 119.52·θCl - 130.84·θDh + 245.69·θDl + 12.35·θMo - 164.46·θMi -
M
95.82)/ρ
(18)
d
Therefore, the air infiltration rate through an existing revolving door can be
te
evaluated from site measurements of the rotation speed (Np) and air temperature at some selected points (Figure 3).
Ac ce p
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4. Conclusions
The results of reduced-scale experiments show that the air displacement flow
rate due to the motion of revolving door increases only slightly with the rotation speed and has a small contribution to the total air infiltration rate, contrary to the previous data obtained some 50 years ago. For the conditions of this study, the air displaced rate is about two orders of magnitude less than the values currently used in the calculation of air infiltration rate. 21
Page 21 of 40
The air infiltration due to the revolution of the door should be included in the provisions of standards and by-laws to help designers for proper estimation of heating loads.
ip t
The correlation-based models developed in this study are proposed to be used, along with the site measurements of the rotation speed and air temperature at some
cr
selected points, for the on-site estimation of the air displacement rates of existing
us
revolving doors.
Future work in laboratory set-up will include models of other scales to evaluate
an
for instance the effect of scale and the influence of buoyancy forces. Other measurement techniques will be tested, such as depressurization with blower door,
Acknowledgments
d
M
on-site on existing revolving doors.
te
The authors acknowledge the financial support from Natural Sciences and Engineering Research Council of Canada and from Faculty of Engineering and Computer
Ac ce p
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Science of Concordia University.
References [1]
Stalder L. Turning architecture inside out: Revolving doors and other threshold devices. Journal of Design History 2009; 22(1): 69-77.
[2]
Schutrum LF, Ozisik N, Baker JT, Humphreys CM. Air infiltration through revolving doors. ASHRAE Journal 1961; 3(11): 43-50.
22
Page 22 of 40
[3]
ASHRAE. ANSI/ASHRAE/IESNA Standard 90.1. Energy Standard for Buildings Except Low-Rise Residential Buildings. American Society of Heating, Refrigerating and Air-conditioning Engineers, Inc., Atlanta, GA; 2010.
[4]
McQuiston FC, Spitler JD. Cooling and heating load calculation manual, 2nd ed.
ip t
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA; 1992.
Zmeureanu R, Stathopoulos T, Schopmeijer MED, Siret F, Payer, J. Measurements
cr
[5]
us
of air leakage through revolving doors of institutional building. ASCE: Journal of Architectural Engineering 2001; 7(4): 131-137. [6]
ASHRAE. ASHRAE standard 90.1. American Society of Heating, Refrigerating
[7]
an
and Air-conditioning Engineers, Inc., Atlanta, GA; 1989.
MNECCB. Model national energy code of Canada for buildings. National Research
[8]
M
Council Canada (NRCC), Ottawa; 1997.
Allgayer DM, Hunt GR. Air movement by revolving doors. Proceedings of
d
Roomvent 2004. Eighth International Conference on Air Distribution in Rooms,
[9]
te
Coimbra, Portugal; 2004.
Alggayer DM, Hunt GR. Hybrid ventilation by revolving doors. Proceedings of Healthy Buildings 2006, Vol. IV, 21-220, Lisboa, Portugal.
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
[10] Allgayer, D. Air and heat movement by revolving doors. LAP LAMBERT Academic Publishing GmbH & Co. KG.
[11] Cullum BA, Lee O, Sukkasi S, Wesolowski D. Modifying habits towards sustainability: A study of revolving door usage on the MIT campus. http://web.mit.edu/wesolows/www/11.366_REVOLVING_DOOR_FINAL_REPORT.pdf,
Cambridge, MA. [Accessed July 2008] [12] Min TC. Winter infiltration through swinging-door entrances in multistory buildings. ASHRAE Transactions; 64, 421. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc, Atlanta, GA; 1958.
23
Page 23 of 40
[13] McGowan A, Jutras R, Riopel G, Hanam M. Heat transfer through roll-up doors, revolving doors and opaque nonresidential swinging, sliding and rolling doors. ASHRAE Research project 1236-RP. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA; 2006.
Fenestration Rating Council, Silver Spring, MD; 2004.
ip t
[14] NFRC 400. Procedure for determining fenestration product air leakage. National
cr
[15] Energy conservation building code 2006. International Institute for Energy
us
Conservation, U.S; 2006.
[16] Fox RW, McDonald AT. Introduction to fluid mechanics, 5th ed. John Wiley &
an
Sons, Inc. New York; 1998.
[17] Halliday D, Resnick R, Walker J. Fundamentals of physics, 8th ed. Wiley:
M
Hoboken, NJ; 2001.
[18] Bérubé Dufour M, Derome D, Tardif M, Zmeureanu R. Measurement of air temperature using infrared thermography in rooms equipped with displacement
d
ventilation in cold climate. Proceedings of the 8th Nordic Symposium on Building
te
Physics, Copenhagen, June; 2008.
[19] Elektror airsystems gmbh. Elektror catalog medium pressure blower. http://pdf.directindustry.com/pdf/elektror/product-review-24355-
Ac ce p
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
7697.html#pdf_7697 [Accessed February 2013].
[20] Aupied A. Measurements, Calculations, Highlights and Visualization of the Heat Loss in a Building Caused by the Rotation of a Revolving Door. Internal report. Concordia University, Montreal; 2009.
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Page 24 of 40
List of Figure Captions
LIST OF FIGURES Figure 1. Dimensions of the experimental box and revolving door without outside insulation
Figure 2. Experimental setup
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Figure 3. Temperature measurement points around the revolving door
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(dimensions in cm)
us
Figure 4. Additional thermocouples outside the door to identify the air flow direction (dimensions in cm)
an
Figure 5. Average rotation speed of revolving doors for different traffic rates measured Figure 6. Volumetric air infiltration rate evaluated for different rotation speeds of the
M
experimental revolving door
Fig. 7. Infrared image on a horizontal screen outside of the revolving door with four seals at N m=
d
50 rpm
300 rpm
te
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at N m=
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Figure 9. Comparison of experimental air infiltration rates due to the revolution of a door at different rotation speeds
Figure 10. Effect of different conditions of seals on the air infiltration rates of revolving doors Figure 11. Dimensionless temperature at thermocouple locations A, B, C, and D around the experimental revolving door
Figure 12. Air temperature distribution outside the door at low rotation speed (Nm = 173 rpm) Figure 13. Air temperature distribution outside the door at high rotation speed (Nm = 296 rpm)
1
Page 25 of 40
Ac ce p
te
d
M
an
us
cr
ip t
Figure(s)
Fig. 1. Dimensions of the experimental box and revolving door without outside insulation (dimensions in mm)
1
Page 26 of 40
T
ip t T
FAN
T
us
T T
cr
HEATER
T
T
T
MOTOR
an
T
Insulation
M
T T T
VARIABLE AUTOTRASFORMER
T
d
POWER SUPPLY
Ac ce p
te
DATA ACQUISITION SYSTEM (DAS)
Fig 2. Experimental setup
2
Page 27 of 40
ip t cr
an
Mi Bh Bl
M
Ch Cl
Dh Dl
us
Ti
Mo
Ah Al
Ac ce p
te
d
To
Fig. 3. Temperature measurement points around the revolving door
3
Page 28 of 40
ip t cr us an M d te Ac ce p
Fig 4. Additional thermocouples outside the door to identify the air flow direction (dimensions in mm)
.
4
Page 29 of 40
ip t cr
8
us
6 5
R² = 0.8918
4
an
Average N (rpm)
7
3 2
0 0
200
M
1 400
from Schutrum et al. (1961) field studies
600
800
1000
1200
te
d
Persons per hour
Ac ce p
Fig. 5. Average rotation speed of revolving doors for different traffic rates measured
5
Page 30 of 40
ip t
0.60
25℃
0.50
40℃
cr
16-21℃
0.70
us
0.40 0.30 0.20 0.10 0.00 0
100
an
Air infiltration rate (L/s)
0.80
200
300
400
M
Experimental rotation speed (rpm)
d
Fig. 6. Volumetric air infiltration rate evaluated for different rotation speeds of the
Ac ce p
te
experimental revolving door
6
Page 31 of 40
ip t cr us an M
Ac ce p
te
d
Fig. 7. Infrared image on a horizontal screen outside of the revolving door with four seals at Nm= 50 rpm
7
Page 32 of 40
ip t cr us an M
Ac ce p
te
d
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at Nm= 300 rpm
8
Page 33 of 40
ip t
100.0
10.0
us
cr
Centrifugal fan with diameter of 21 cm
1.0
an
lg(Air flow rate) (L/s)
Schutrum et al. (1961)
Experimental results from this research
0.1 0
100
200
300
400
500
d
M
Experimental rotation speed (rpm)
te
Fig. 9. Comparison of experimental air infiltration rates due to the revolution of a door at
Ac ce p
different rotation speeds
9
Page 34 of 40
ip t cr
1.20
Without vertical seals
1.00
us
0.80
With two wings having seals
0.60 0.40
an
Experimental air infiltration rate (L/s)
1.40
With full seal condition
0.20 0.00
100 200 300 400 Experimental rotation speed (rpm))
500
d
M
0
doors
Ac ce p
te
Fig. 10. Effect of different conditions of seals on the air infiltration rates of revolving
10
Page 35 of 40
ip t
R² = 0.8789
A
cr
0.80
B
R² = 0.3842
0.60 0.40
R² = 0.8839
0.20
us
C
an
Dimensionless temperature
1.00
Ti
D
Ch Cl
Mi
Dh Dl
Mo
Bh Bl
R² = 0.6971
0.00
100 200 300 Experimental rotation speed (rpm)
400
Ah Al To
te
d
M
0
Fig. 11. Dimensionless temperature at thermocouple locations A, B, C, and D around
Ac ce p
the experimental revolving door
11
Page 36 of 40
ip t cr 6.31 (0.34) 3.99 (0.21) 2.74 (0.15)
an
To (°C) 6.34 (0.34) (θx)
Door holder
us
Ti – To = 18.5 °C Nm = 173 rpm
3.12 (0.17)
6.34 (0.34) 2.92 (0.16)
3.98 (0.22) 3.17 (0.17)
Ac ce p
te
d
M
2.92 (0.16)
4.95 (0.27)
Fig. 12. Air temperature distribution outside the door at low rotation speed (Nm = 173 rpm)
12
Page 37 of 40
3.84 (0.27) 1.63 (0.12)
M
1.90 (0.14) 1.76 (0.13)
us
cr
ip t 3.26 (0.23)
4.67 (0.33) 3.53 (0.25) 1.67 (0.12)
Door holder
4.07 (0.29) 2.89 (0.21) 1.23 (0.09)
Ac ce p
te
d
To (°C) (θx)
an
Ti – To = 14 °C Nm = 296 rpm
Fig. 13. Air temperature distribution outside the door at high rotation speed (Nm = 296 rpm)
13
Page 38 of 40
Outdoor
Indoor
Ac ce p
te
d
M
an
us
cr
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Graphical Abstract (for review)
Fig. 8. Infrared image on a horizontal screen outside of the revolving door with four seals at Nmodel = 300 rpm
1
Page 39 of 40
*Highlights (for review)
Highlights We present results from a reduced-scale physical model of revolving door Air displaced by door rotation is two orders of magnitude inferior to previous data
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Increasing the door rotation speed does not increase significantly the air displaced
Ac ce p
te
d
M
an
us
cr
Correlation-based models to be used for on-site estimation of the air displacement
Page 40 of 40