- Email: [email protected]
Computational modeling of particle transport and distribution emitted from a Laserjet printer in a ventilated room with different ventilation configurations
Applied Thermal Engineering 103 (2016) 920–933
Contents lists available at ScienceDirect
Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng
Research Paper
Computational modeling of particle transport and distribution emitted from a Laserjet printer in a ventilated room with different ventilation configurations Mehrzad Ansaripour, Morteza Abdolzadeh ⇑, Saleh Sargazizadeh Department of Mechanical Engineering, Graduate University of Advanced Technology, Kerman, Iran
h i g h l i g h t s The distribution of emitted particles form a laserjet printer was studied in the breathing zone. Effects of different ventilation configurations on the breathing zone concentration were investigated. Mixing ventilation system has a low mean particle concentration in the breathing zone.
a r t i c l e
i n f o
Article history: Received 3 February 2016 Revised 25 April 2016 Accepted 25 April 2016 Available online 26 April 2016 Keywords: Printer Ventilation Heated manikin Transport Particle Distribution
a b s t r a c t In the present research, computational modeling of particle transport and distribution emitted from a Laserjet printer was carried out in a ventilated room. A seated manikin was integrated into the study room and the manikin was evaluated in two cases: heated and unheated. Effects of different ventilation configurations of the room on the particle distribution were studied, including three displacement ventilation systems and a mixing ventilation system. The printer was located on different sides of the manikin and the particle concentrations in the breathing zone of the manikin due to the printer’s particles were evaluated in all the ventilation configurations. The averaged particle concentration in the breathing zone of the manikin was calculated and validated with the experimental and numerical data available in the literature. The results of the present study showed that in case of the heated manikin, the particle concentration due to the printer pollutants is significant in the breathing zone of the manikin. The results also showed that when the printer is located on the front side of the manikin, the particle concentration in the breathing zone is quite high in most of the used ventilation configurations. Furthermore, it was found that the mixing ventilation system has a lower mean particle concentration in the breathing zone compared to the most displacement ventilation systems. Ó 2016 Elsevier Ltd. All rights reserved.
1. Introduction Nowadays, many people are spending the majority of their day times in indoor spaces and are highly affected by the emitting particles released from copier machines and printers [1,2]. The electronics and computer engineering systems have been extensively used in the mankind life since their early development. These systems emit particles in indoor places and are known as an active source of particle generation as these systems, mostly release volatile and semi-volatile particles while they are working. ⇑ Corresponding author at: Department of Mechanical Engineering, Graduate University of Advanced Technology, End of Haft Bagh Highway, Kerman, Iran. E-mail addresses: [email protected], [email protected] (M. Abdolzadeh). http://dx.doi.org/10.1016/j.applthermaleng.2016.04.137 1359-4311/Ó 2016 Elsevier Ltd. All rights reserved.
These particles have different patterns and effects on the breathing zone of the human body based on the ventilation configurations and the location of a printer in rooms. These matters are very important to select the right ventilation systems and also the position of the printer in the room. The past studies [3,4] have indicated a tight relationship between the level of emitting pollutant particles and the adverse health effects such as early death and hospitalization (short term effects) plus lung cancer and cardiovascular diseases (long term effects). Indoor air quality (IAQ) is highly dependent on the number of particles penetrating into the indoor places from outside or inside spaces. In recent years, it has been indicated that the particles emitted from printers affect the indoor air quality of offices [5,6]. General characteristics of printer’s emissions like particle concentration and particle deposition rate can be experimentally
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
921
Nomenclature Ain C C0 Cc Cva Cpa d Gi g k nj n N p Rep S ti Tf T T1 tp u, v, w
inlet register area (m2) particle concentration (kg/m3) inlet particle concentration (kg/m3) Cunningham coefficient volume averaged concentration (kg/m3) plane averaged particle number concentration (kg/m3) Particle diameter (lm) Gaussian random number with zero-mean gravitational acceleration (m/s2) turbulent kinetic energy (m2/s2) the stochastic phenomenon of the Brownian diffusion number of particles that move across the plane having an area of A number of injected particles the air pressure (pa) Reynolds number based on velocity of particles relative to air ratio of particle density to fluid density the particle residence time (s) fluid absolute temperature (K) the sampling time (s) ambient temperature (K) relaxation time (s) velocity components (m/s)
measured in an experimental enclosed box. However, this determination of particle transportation and distribution is quite hard to achieve. This issue essences using computational fluid dynamics (CFD) as a useful tool to help understanding of the emitted pollutant particle behavior better. So far, many studies have been experimentally carried out in order to clarify the printer emission characteristics. For instance, Lee et al. investigated the emissions rate of pollutants from different types of office equipment. They showed that the emissions of ozone and VOC in laser printers are significantly higher than that of ink-jet printers [7]. Kagi et al. monitored the air contamination released from a laser printer/ ink-jet printer in a room. Their results confirmed an increase of the ozone concentration and ultrafine particle numbers in the printing processes [8]. He conducted an experiment and measured particle number concentrations and PM2.5 emissions from printers in a large open-plan office. They revealed that the particles generated by printers can significantly affect the levels of submicrometer particle number concentration in the office [9]. Hugo et al. reviewed available information on emission rates and also ambient concentrations of various pollutants which were related to office equipment use. The evaluated office equipments were computers (desktops and notebooks), printers (laser, ink-jet and all-in-one machines), and photocopier machines. They identified the toxicological substances significant in order to prepare a guide for evaluating their potential importance with respect to human exposures [5]. Morawska et al. carried out an experimental research which determined the particle composition, particle formation mechanism, and emission rate of Laserjet printers. They indicated that the emission rates of ultrafine particles of the printers are directly due to the Fuser temperature. They also showed that the particles are volatile and have a secondary nature, being formed in the air from volatile organic compounds originating from both the paper and hot toner [6]. Byeon and Kim investigated particle emissions for commercial color laser printers working under different printing speeds in an experimental chamber. They showed that the average particle number concentration is inversely proportional to the printing speed [10].
vP
V xi
v 02F
the particle velocity at the inlet register (s) measurement volume (m3) particle position (m) squared airflow fluctuation velocity normal to the wall (m2/s2)
Greek symbols qf fluid density (kg/m3) e Turbulent kinetic energy dissipation rate l fluid viscosity (kg/m s) k mean free path of the air molecules (lm) tt air flow turbulent viscosity (m2/s) Subscript m w in p f
mean wall inlet particle phase fluid
Superscript + dimensionless Reynolds averaging
A series of studies have focused on particle transport and distribution when a manikin was present in a room. For instance, Spitzer [11] and Spitzer et al. [12] carried out some experiments to study the effect of particle motion on the breathing zone of a seated breathing manikin. They revealed that the particle’s motion significantly affects the particle concentration of the breathing zone. Melikov and Kaczmarczyk [13] investigated the importance of the breathing zone of a thermal manikin when the indoor particles are inhaled. Rim and Novolselka investigated the airflow in the vicinity of a human body. They considered the effects of respiration on the breathing zone concentration of particulate and gaseous pollutants, and inhalation exposure in relation to source position and overall airflow patterns. They indicated that the overall airflow pattern influences the inhaled particle concentrations. They also revealed that highly mixed airflow in the space creates relatively uniform concentration patterns in the vicinity of the occupant. However, they also showed that the occupant thermal plume makes non-uniform concentration patterns [14]. Zukowska et al. studied several effects such as thermal insulation, the design of clothing and the chair, the blocking effect of tables on the thermal plume generated above a seated thermal manikin in a chamber [15]. Salmanzadeh et al. studied the buoyancy driven thermal plume near a sitting heated manikin. They showed that a high concentration of suspended particles in the breathing zone is seen due to the thermal plume flow created by the temperature gradient adjacent to the body [16]. Li et al. investigated effect of thermal manikin position on the characteristics of particle transport and inhalation. They revealed that the manikin orientation has a significant impact on the characteristics of particle transport and inhalation. They showed that for an occupant standing with its back towards the horizontal airflow, a little change in the leg posture can lead to an obvious variation in the source location of inhaled particles [17]. In the present study, particle transport and distribution emitted from a Laserjet printer in a ventilated room, which is scarce in the past studies, were computationally simulated using computational fluid dynamics. Combined Eulerian and Langragian methods were
922
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
applied to simulate the airflow field and the printer particle motion in the room. The printer was considered as the sole source of particle generation inside the room. A seated manikin was integrated into the study room and in order to take into account the thermal plume generated in the vicinity of the manikin body, it was evaluated in two cases: heated and unheated. Different ventilation configurations for the room were studied, including three displacement systems and a mixing ventilation system. The printer was located on different sides of the heated manikin and then the particle concentration was evaluated in the breathing zone of the manikin in all the ventilation configurations. The fluid flow and particle motion simulations were validated by Sorenson and his co-worker study [18] and Mar’s study [19], respectively. This study provides useful information on a printer emission distribution in a ventilated room with a seated manikin inside alongside with influence of printer location on the particle concentration in the breathing zone of the heated manikin to find the best location of the printer in the room. 2. System description Fig. 1 shows the schematic of the ventilated room used in this research. A cubicle with dimensions of 1.8 2.2 2.2 m was chosen and a seated female manikin was placed at the middle of the cubicle. It should be mentioned that the manikin geometry was borrowed from the database (http://www.ie.dtu.dk/manikin) addressed in Sorenson and Voigt study [18]. A Laserjet printer was used in this study and it was located 0.4 m away from the manikin and 0.75 m from the ground. To evaluate particle concentration in the breathing zone, an area of 0.07 0.07 m2 was selected in the front of manikin face and the mean concentration of passed particles across this area was calculated. The emission of printer particles was considered as a surface injecting source and released from an area of 0.09 0.09 m2 above the printer
head. The particle phase was assumed dilute. In the present CFD analysis, the room was studied with four different ventilation configurations, including three displacement ventilation systems as well as a mixing ventilation system shown in Figs. 1 and 2 and given in Table 1. 3. Governing equations and numerical methods 3.1. Fluid flow phase The airflow in the cubicle was simulated using the v2–f turbulence equations [20,21] as well as the energy equation. The model formulation has the following general form:
q
@/ @/ @ @/ j ¼ S/ þ qu C/;eff @t @xj @xj @xj
ð1Þ
where / represents the independent flow variables, C/;eff the effective diffusion coefficient, S/ the source term, q the flow density and the bars denote the Reynolds averaging. In Table 2 the mathematical form of each transport equation of the v2–f model are summarized. p is the air pressure, lt the turbulent viscosity, S the rate of strain, f a part of the v02 source term and Tl the turbulent time scale. The appropriate boundary conditions of turbulence variables near the walls are as follows:
k ¼ v 02 ¼ 0;
e ¼ 2t
k y2p
ð2Þ
yp is the distance from the cell center to the wall. In this study, commercial CFD software, FLUENT (version 6.2), was used to predict the turbulent airflow. The v2–f model used in this study is based on Davidson et al. [21] study Turbulent intensity, temperature, and velocity were considered 30%, 20 °C, and 0.2 m/s, respectively, in the inlet registers. The manikin body’s
Fig. 1. Sketch of the system studied in the present study.
923
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Fig. 2. Different ventilation configurations used in the present study.
Table 1 Configurations of different ventilation systems used in this study.
Table 3 Particle characteristics released from the printer. N0 (Particle/s)
Mixing ventilation system System I
Displacement ventilation system System II
System III
System IV
Inlet and outlet 4
Inlet and outlet 3
Inlet and outlet 2
Inlet and outlet 1
temperature and the temperature of cubicle walls were taken 31 °C and 19.75 °C, respectively. The pressure outlet boundary condition was given in the outlet registers of the cubicle. The manikin was considered in two cases: heated and unheated. The buoyancy movement due to the generated thermal plume was taken into account in the particle distribution calculation. This has been carried out taking the manikin as a constant temperature body which its temperature is higher than the surrounding air. Note, the impact of buoyant air movement was transferred to the particle phase by calculating the air velocity in the vicinity of the manikin and applying it on the particles. An unstructured grid (tetrahedral cell topology) was applied for surrounding air of the manikin. To resolve the boundary layer around the manikin, fine meshes were created at the surface of the manikin with an initial height of 0:2 mm, and a growth rate of 1.13. The energy equation was not solved in the unheated case as the flow was isotherm. It should be pointed out, these boundary conditions are the same in all the ventilation systems considered in this study. The unstructured mesh and the finite volume method as well as the SIMPLE algorithm were used to solve the governing equations. Grid
510
9
dp (lm)
qp (kg/m3)
Vp (m/s)
0.05
2000
0.2
dependency analysis of the computational domain was carried out and a computational mesh containing about 1.13 106 cells showed a sufficient accuracy for continuing the analysis, Table 4. 3.2. Particle phase So far, several experiments for determination of printer particle characteristics such as rate of emitting particles, particle diameter, particle density, and particle temperature have been carried out in the past studies [6,10]. The particle characteristics released from the printer are given in Table 3. The emission of particles into the cubicle was considered with a time interval of 3 min for the printing process. A concentration of 5 109 particles-cm3 was considered as the emission source of the cubicle released from the printer [10]. It was reported that when the printing is getting started an average particle size of 50 nm (50 prints/min) comes out of the printing process. It also should be pointed out that due to the temperature difference between the hot air generated in the printer and the surrounding air, the emitted particles move upward from the printer head. To take into account this fact, it was assumed that the particles are emitted into the air with an initial velocity of 0.2 m/s. It should be stated that this velocity
Table 2 Coefficients and source terms in Eq. (1). Name of conservation equation
Independent flow variable /
Effective diffusion coefficient C/;eff
Source term S/
Continuity X-Component of momentum
1 U
0
0
Y-Component of momentum
V
tt þ t tt þ t
Z-Component of momentum
W
tt þ t
Energy Turbulent kinetic energy (k) Turbulent kinetic energy dissipation rate (e) Wall normal turbulence fluctuation to kinetic energy (uÞ
Tf K E
kf þ tt=rT tt =rk;t þ t tt =re;t þ t tt =ru þ t
ðv02 =kÞ
pffiffiffiffiffiffiffiffiffiffi L2 Da a ¼ 1; Gk ¼ tt S2 ; S ¼ Sij Sij ; Su ¼ ð1 ap Þf w þ ap f h Gk u=k. pffiffi f h ¼ T1l C 1 1 þ Gek ðu 2=3Þ; f w ¼ uke T l ¼ max ke ; C T me . 3=2 3=4 L ¼ C L max k e ; C g te1=4 ; P k ¼ 2C l v02 TS2ij . qffiffiffi tt ¼ C l ; ku T l ; C 0e1 ¼ 1:44 1 þ 0:04ð1 ap Þ u1 . C e2 ¼ 1:83; C 1 ¼ 1:7; C 2 ¼ 1:2; C l ¼ 0:22; C L ¼ 0:161; C g ¼ 90; C T ¼ 6; rk;t ¼ 1; re;t ¼ 1:22; ru;t ¼ 1; p ¼ 3.
@ q1 @p @x þ @x @ q1 @p @y þ @x
@u
@ @v @ @w tt @u @x þ @y tt @x þ @z ðtt @z Þ
@ q1 @p @z bgðT f T 1 Þ þ @y
0 Gk e ðC 0e1 Gk C e2 eÞ=T l
@k @ u a t þ tt =rk;t Þ @x þ Su j @xj
2 ð p k
tt @x þ @y@ tt @@yv þ @z@ tt @w @z
@ @w tt @@yv þ @x@ tt @u @y þ @z tt @z
924
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Table 4 Checking the solution gride dependency. Cell number
54,000
434,000
691,700
922,147
1,129,885*
1,357,557
Skin friction coefficient of the manikin body Convective heat transfer coefficient in the vicinity of the manikin (W/m2 K) Air Temperature, 5cm away from the manikin face (K)
0.000182 1.14 293.88
0.000383 1.82 294.17
0.000878 2.67 294.33
0.000959 2.62 294.38
0.00232 2.44 294.57
0.00227 2.38 294.54
*
The optimum mesh number.
was selected based on the maximum air velocity created above the printer head due to the released heat of the printer while is printing and it was found doing a separate simulation of the air above the printer. The released heat of the printer was assumed 40 W. 3.2.1. Mathematical modeling of particle motion and particle concentration distribution The Lagrangian point of view was used to model particle transport in the air. The following equations were used to simulate movement of spherical particles: p
dxj ¼ upj dt
ð3Þ
p 5:188v 1=2 d 1 þ 0:15Re0:687 duj d ij ujf upj þ ujf upj ¼ 1=4 dt sp Sdðdlk dkl Þ
1 þ nj ðtÞ þ 1 g s i
ð4Þ
where ujf ¼ ui þ u0j which ui is the mean flow velocity at the particle location, u0j is the flow fluctuation velocity, upj is the velocity of particles at the center of the particles, xi is the particle position, t is time, d is the particle diameter, S is the ratio of particle density to fluid density, and gi is the gravitational acceleration. Re ¼ ju f up jd=v is the particle Reynolds number based on the
Fig. 3. Velocity distribution (m/s) in the mid plane of the cubicle. (a) Unheated manikin. (b) Heated manikin in System (IV).
925
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Velocity
Velocity
Temperature (a)
Temperature (b)
Fig. 4. Vertical Velocity (m/s) and Temperature (°C) distributions around the manikin body (a) present study (b) Sorenson and Voigt [18] study.
flow-particle slip velocity. The first term on the right-hand side of Eq. (4) stands for the Stokes drag. Here, sp is the Stokes relaxation time and is as follows [22,23]:
sp ¼
2
d SC c 18v
ð5Þ
Cc is the Stokes–Cunningham correction factor which modifies the drag force exerted to ultrafine particles due to slip and is:
Cc ¼ 1 þ
k 0:8 2:514 þ 0:55d=k d e
ð6Þ
The second term on the right right-hand side of Eq. (4) presents the contribution of the Saffman lift force. The third term in Eq. (4), nj(t), represents the stochastic phenomenon of the Brownian diffusion. This force is modeled by a Gaussian random number with zero-mean, unit variance, Gi, as [24]:
nj ðtÞ ¼ Gi
216
p
vr
T q f d5 S2 C c Dt
ð7Þ
The fourth term in Eq. (4) is particle gravitational force. To calculate the particle concentration in the room as well as the concentration in the breathing zone of the manikin due to the printer particle generation, plane and volume averaged particle number concentrations are obtained. The method of Hardalupas and Taylor [25] implemented by Zhu et al. [26] was used to calculate the volume averaged concentration. Based on this method, the particle number concentration is as follows:
Pn Cva ¼
i¼1 t i
ð8Þ
VT
where n is the number of particles that move across the measurement volume V, and ti is the particle residence time in the
-0.1
(a)
!1=2
(b)
-0.05
0
y
0.05
0.1
(c)
Fig. 5. Vertical velocity (m/s) distribution above the manikin head (a) experimental study [18] (b) numerical study [18] (c) present simulation.
926
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
(a)
Present Study Experiment [27]
(b) Lai and Chen [27] Empirical Equaon [27] Present Study
(c) Fig. 6. (a) Experimental chamber, (b) comparison of particle concentration in the mid-plane of chamber at different x-locations and (c) deposition fraction in the chamber vs. different particle sizes with the experimental data [27].
measurement volume, and T is the sampling time. The plane averaged particle number concentration, Cpa, is calculated as follows:
C pa
Pn 1=v pi ¼ i¼1 AT
ð9Þ
the calculated concentrations in the breathing zone. The normalized volume averaged concentration is given as:
Pn ti =V C þv a ¼ i¼1 t N=Ain v in
ð10Þ
The plane averaged concentration is as follows: where n is the number of particles that move across the plane having an area of A with a normal velocity vp. It should be stated that the average concentration at the inlet was used to normalize
C þpa
Pn p A i¼1 1=v i ¼ N=Ain v tin
ð11Þ
927
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
(a)
Manikin head V(m/s)
V(m/s)
V(m/s)
[19]
(b)
(c)
[16]
(d)
Fig. 7. (a) The room and the manikin position used in the experimental study [28] and the computational study [19], vertical velocity distribution above the manikin head (b) present study (Sorenson and Voigt’s Manikin) (c) experimental study (Mar’s Manikin) [19] (c) computational study (Mar’s Manikin) [16].
where N is number of injected particles and velocity at the inlet register with an area of Ain.
vP
is the particle
Numerical Study[16] Experiment [19] Present study
The particle equation of motion was solved using the discrete phase of FLUENT software. The concentration equations listed above were solved using a homemade computer code written in MATLAB. This code was later linked to the discrete phase model of FLUENT to obtain the particle concentration in the breathing zone.
4. Results and discussion 4.1. Fluid flow analysis
Fig. 8. Comparison of normalized plane average concentrations of the manikin breathing zone, between the present simulation and the numerical [16] and the experimental studies [19].
In this section, first, the fluid flow inside the cubicle is evaluated. The fluid flow was investigated in two cases: heated and unheated manikins. Fig. 3(a) shows the velocity distribution inside the cubicle when the manikin is unheated. In this case, the energy equation is not solved. As shown in this figure, the fluid flow entered from the inlet register is directly moving upward and the maximum velocity location is away from the manikin. In case of the heated manikin, the buoyancy force is added to the momentum equation due to the temperature difference between the manikin and the ambient air. In this case, shown in Fig. 3(b), the maximum air velocity is seen above the manikin head and a secondary flow is created over the head. To check the simulation results accuracy,
928
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Unheated
Heated
t=25s
t=75s
t=130s Fig. 9. Particle dispersion in the cubicle at different time histories for the unheated and heated manikins in System IV.
the present study was compared with Sorenson and Voigt [18] numerical and experimental results. It should be mentioned that in their study the inlet was on the bottom side and the outlet was from the cubicle ceiling. The flow velocity was 0.02 m/s and its turbulent intensity was 30%. The temperatures of the walls and the manikin were assumed equal. It should be mentioned that the Sorenson geometry as well as the its boundary conditions were simulated and then the results of the simulation were compared with the measured data The comparisons of the velocity and temperature around the manikin are shown in Fig. 4(a) and (b). As shown in these figures, the present study predicts the velocity and temperature with a sufficient accuracy compared to the Sorenson et al. numerical results. Fig. 5 shows the comparison of the vertical flow velocity above the manikin head with the numerical and experimental results of Sorenson and his coworkers. As shown in
this figure, the present simulation predicts the vertical velocity with a sufficient accuracy compared to the experimental data. 4.2. Particle trajectories and distribution 4.2.1. Validation of the particle model with no manikin In this section, the particle phase is validated using an experimental data which were measured in an experimental chamber [27] The dimensions of the chamber were 0.4 0.4 0.8 m (Fig. 6(a)) and the inlet velocity was 0.225 m/s. Particle diameter and density were 10 lm and 1400 kg/m3, respectively, and the particles were released from the inlet register. Fig. 6(b) shows the comparison of particle concentrations vs. the chamber height in different x locations of the chamber. As shown in this figure, the v2–f model along with the particle model predict the particle distri-
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Fig. 10. Normal particle concentration in the breathing zone for heated and heated manikins.
bution with a reasonable accuracy. Fig. 6(c) shows the comparison of deposition fractions in the experimental chamber using the present numerical model and the experimental data in the particle range of 0.01–10 lm. These figures show that the accuracy of the present numerical model is sufficient for pursuing the goal of present simulation.
4.2.2. Validation of the particle model with the manikin In this section, the particle concentration distribution in the breathing zone of the manikin is compared with the computational
929
and experimental studies [16,19] conducted in the past studies. The inlet velocity was 0.2 m/s. Particle diameter and density were 1 lm and 2000 kg/m3, respectively, and the particles were released from the inlet register. Fig. 7(a) shows the study room and the corresponding ventilation systems which were used in this study. It should be mentioned that their ventilation system is the same as System IV with the equal dimensions used in the present study. As the manikin used in the present study is a female manikin and in those studies is a male manikin, it is first required to compare the velocity distributions of all the studies in order to check out the likely difference of the flow characteristics around the manikin. It should be stated that in that two studies [16,19] as well as present study, the manikins were considered as heated manikins and their body temperature was taken 32.2 °C. The air flow characteristics at the inlet register in all the studies are the same as information given in Section 3. Fig. 7(b)–(d) shows the velocity magnitude above the manikin head computed in the present study with female manikin and Salmanzadeh et al. study [16] and Mar and Mar et al. studies [28,19] with the male manikin. As shown in this figure, the velocity distribution above the manikin head is close to the experimental study and this means that the difference between the present study and those two studies [16,19] in term of manikin gender is negligible as the present simulation predicts the flow velocity with a reasonable accuracy. These figures also show
Fig. 11. Velocity distributions (m/s) in the mid plane of cubicle in Systems (a) III (b) II and (c) I.
930
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Normalized Concentaron
Fig. 12. Normalized particle concentration of the breathing zone in all the ventilation systems – printer located in the front of the manikin.
1.4
System IV
System III
System II
System I
1.2 1 0.8 0.6 0.4 0.2 0
BACK
FRONT
LEFT
RIGHT
Fig. 14. Normalized particle concentration in the breathing zone for different printer positions in all the ventilation systems (I, II, III, and IV).
Fig. 13. Different printer locations around the manikin.
that the velocity distribution of the present study is more similar to the experimental study compared to Slamanzedh et al. [16] study. Fig. 8 shows the average particle concentration in the plane of the breathing zone of the manikin located at different distances of the manikin’s face. In all the studies, 10,000 particles with 1 lm diameter were injected from the inlet register for 10 min in the steady state condition. Fig. 8 shows that the present study predicts the particle concentration with a reasonable accuracy compared to the experimental study. However, there are still some differences between the present simulation and the experimental date at some distances. These differences are due to: the experimental data which were measured while the manikin was breathing, which was not taken into account in this study and also the likely minor differences between the shape of the applied manikin in the present study and Mar’s study. However, differences between the measured and the simulated data for the first two points are less than 10% and it should be mentioned that Marr [19] reported his measured data with 15% uncertainty. 4.2.3. Particle concentration distribution due to the printer emission The particle concentration distributions due to the printer pollutants for the heated and unheated manikins with the ventilation
system (IV) at different time histories of particle emission are shown and compared in Fig. 9. As shown in this figure, the breathing zone is less affected in case of the unheated manikin and this is condition does not exist when the manikin is considered as a heat generating body. In this case, the breathing zone is significantly affected due to the emitted particles and this issue is more pronounced at the higher time histories of emission. This figure also shows that the particle accumulations in the breathing zone of the unheated case at the lower time histories are not significant, but in the heated case, the breathing zone from the beginning of particle emission is in a bad condition. Comparison of normal particle concentrations in the breathing zone of the manikin for the two above mentioned cases with 180 s passed time, are shown in Fig. 10. As shown in this figure, the average particle concentration of the heated manikin is 6 times larger than the unheated one. It is also revealed that the location of printer highly affects the quantity of particle concentration in the breathing zone and needs more attention and consideration. 4.2.4. Effect of different ventilation configurations on particle concentration of the breathing zone 4.2.4.1. Printer located in front of the manikin. In this section, the three other ventilation configurations described in Section 2 are evaluated when the printer is located in the front of the manikin. The velocity distributions in the mid plane of the cubicle are shown in Fig. 11(a), (b), and (c) for systems III, II, and I, respectively. As shown in these figures as well as Fig. 4, the maximum velocity in
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
931
Fig. 15. Velocity distributions (a) in the mid plane of cubicle in x direction (b) the plane in the right of the manikin (c) the plane in the left of the manikin.
the breathing zone among all the systems is seen in the system (IV) (Fig. 4). This is due to the inlet air register which is located in the front of manikin and creates the maximum air movement in the breathing zone. This speed is decreased in systems III, II, and I, respectively. System III also has a high air speed in the breathing zone, but still lower than system IV as the air register in this system does not directly blow the air through the breathing zone area. System (I) has the lowest air movement in the breathing zone as the inlet register is located in the back side of manikin close to the ground and in this case the air movement in the breathing zone is mostly due to the thermal heat plume generated around the manikin body. The particle concentration distributions in the breathing zone of all the configurations are shown in Fig. 12. As it was expected from the flow analysis of all the systems and shown in this figure, system IV and system I have the highest and lowest particle concentrations, respectively, in the breathing zone of the manikin. This matter is mostly due to the air speed in the breathing zone. System IV has the maximum particle concentration in the breathing zone due to the air register location which is the worst place for the inlet register among all the systems. System I show a good performance to remove the particle released from the front of manikin without directing them toward the breathing zone. This fact is due to the location of inlet air register on the back side of the manikin which makes the air flow to
move above the manikin head and suck the particle from the printer head and deliver them to the outlet register. 4.2.4.2. Printer located on the other sides of the manikin. In this section, the printer is located on the other sides of the manikin (Fig. 13) and then the particle concentration of the breathing zone in each ventilation configuration is obtained and compared with one another in order to find the best printer location in the corresponding configuration. The particle concentrations of the breathing zone in all the configurations are shown in Fig. 14. As shown in this figure, the system (IV) has the maximum and minimum concentrations among all the configurations when the printer is located in the front and back sides of the manikin. This fact clearly says that the printer should be located in the back side of the manikin in System (IV) as in this case the released particles do not cross the breathing zone and make this area safe from the particle pollution. This figure also shows that system (I) has the maximum particle concentration when the printer is located on the right, left, and back sides of the manikin. The large particle concentration in the back side of the manikin is due to the printer location which directs the emitted particle into the air and they cross the breathing zone in the way of approaching the outlet register. It is also revealed that the right and left sides of the manikin also are not good places for the printer as the released particles from these
932
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Mean normal concentraon
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
System I
System IV
System II
System III
(a) Normalized cincentraon
0.9 0.8 0.7 0.6
into the study room and it was evaluated in two cases: heated and unheated. To find the best place of the printer with the lowest particle concentration of the breathing zone in the study room, the printer was located on different sides of the manikin and the breathing zone particle concentrations of the heated manikin were evaluated in all the ventilation configurations. The results of the present simulation show that the printer’s particle emission highly affects the enhancement of particle concentration in the breathing zone of the heated manikin. It was also revealed that when the printer is located in the back side of the heated manikin, the minimum particle concentration of the breathing zone is seen in all the ventilation configurations which suggests the best area of the printer location. This trend of the concentration in the breathing zone is completely opposite when the printer is located in front of the manikin. Furthermore, It was also concluded that the mixing ventilation system has a lower mean particle concentration in the breathing zone compared to the displacement ventilation systems.
0.5 0.4
References
0.3 0.2 0.1 0
BACK
RIGHT
LEFT
FRONT
(b) Fig. 16. Mean normalized concentration of the breathing zone based on (a) the ventilation configurations (b) the printer locations.
places, place the breathing zone at more risk compared to the back side of the manikin. All these observations suggest that the best place of the printer in System (I) is the front side of the manikin. It should be pointed out that the symmetry condition of the fluid flow due to the buoyancy effect created in the vicinity of manikin leg is not held between the right and the left sides of the manikin body as shown in Fig. 15. This fact has also been reported in the past studies [15,29,30]. The unsymmetrical condition yields different particle concentration quantities in systems (I), (II), and (IV). However, the differences between the concentrations of the right and left sides in the above mentioned systems are negligible. Fig. 16(a) shows the mean normalized concentration in the breathing zone averaged over all the printer locations for each configuration. This figure states that the mixing ventilation system (system II) is more suitable than the displacement systems in case of particle emission in the breathing zone. It is also shown that the maximum normal concentration among all the displacement ventilation systems happens to system I. It is also revealed that the best displacement system is System (III) as in this case the manikin is rotated 90° with respect to the inlet register. Fig. 16 (b) shows the mean particle concentration which is the average of particle concentration of all the systems for all the manikin sides. As shown in this figure, the back and front sides of the manikin have the lowest and highest particle concentrations in the breathing zone, respectively. It means that the front side of the manikin in all the systems except system (I) is the worst place for the printer. The right and left sides of the manikin also have high particle concentrations in the breathing zone and this also shows that these places are not good places for the printer.
5. Conclusion In this study, the pollutant particles emitted from a Laserjet printer were computationally simulated in a ventilated room with four ventilation configurations. A seated manikin was integrated
[1] R.D. Brook, S. Rajagopalan, C.A. Pope, et al., Particulate matter air pollution and cardiovascular disease: an update to the scientific statement from the American heart association, Circulation 121 (2010) 2331–2378. [2] S.S. Lim, T. Vos, A.D. Flaxman, et al., A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010, Lancet 380 (2012) 2224–2260. [3] C. Iribarren, I.S. Tekawa, S. Sidney, G.D. Friedman, Effect of cigar smoking on the risk of cardiovascular disease, chronic obstructive pulmonary disease, and cancer in men, New Engl. J. Med. 340 (1999) 1773–1780. [4] J. Guo, T. Kauppinen, P. Kyyronen, P. Heikkila, M.L. Lindbohm, E. Pukkala, Risk of esophageal, ovarian, testicular, kidney and bladder cancers and leukemia among finnish workers exposed to diesel or gasoline engine exhaust, Int. J. Cancer 111 (2004) 286–292. [5] Hugo Destaillats Randy, L. Maddalena, Brett C. Singer, Alfred T. Hodgson, Thomas E. McKone, Indoor pollutants emitted by office equipment: a review of reported data and information needs, Atmos. Environ. 42 (7) (2008) 1371– 1388. [6] L. Morawska, C. He, G. Johnson, R. Jayaratne, T. Salthammer, H. Wang, E. Uhde, T. Bostrom, R. Modini, G. Ayoko, P. Mcgarry, M. Wensing, Laser Printers : A Source of Nanoparticles in Indoor Office Environments. No December, 5–9, 2009. [7] S.C. Lee, S. Lam, H.K. Fai, Characterization of VOCs, ozone, and PM 10 emissions from office equipment in an environmental chamber, Build. Environ. 36 (2001) 837–842. [8] N. Kagi, S. Fujii, Y. Horiba, N. Namiki, Y. Ohtani, H. Emi, H. Tamura, Y.S. Kim, Indoor air quality for chemical and ultrafine particle contaminants from printers, Build. Environ. 42 (5) (2007) 1949–1954. [9] C. He, Office particle emission characteristics of office printers CONGRONG, Environ. Sci. Technol. 6039–6045 (2007). [10] J.H. Byeon, J.W. Kim, Particle emission from laser printers with different printing speeds, Atmos. Environ. 54 (2012) 272–276. [11] I.M. Spitzer, Experimental Aerosol Characterization in the Indoor Environment Using Phase Doppler Anemometry Master’s Thesis, Syracuse University, 2006. [12] I.M. Spitzer, D.M. Marr, M.N. Glauser, Impact of manikin motion on particle transport in the breathing zone, J. Aerosol Sci. 41 (2010) 373–383. [13] A. Melikov, J. Kaczmarczyk, Measurement and prediction of indoor air quality using a breathing thermal manikin, Indoor Air 17 (1) (2007) 50–59. [14] Donghyun Rim, Atila Novosela, Transport of particulate and gaseous pollutants in the vicinity of a human body, Build. Environ. 44 (2009) 1840–1849. [15] D. Zukowska, A. Melikov, Z. Popiolek, Impact of personal factors and furniture arrangement on the thermal plume above a sitting occupant, Build. Environ. 49 (104–116) (2011) 2012. [16] M. Salmanzadeh, G. Zahedi, G. Ahmadi, D.R. Marr, M. Glauser, Computational modeling of effects of thermal plume adjacent to the body on the indoor airflow and particle transport, J. Aerosol Sci. 53 (2012) 29–39. [17] X. Li, K. Inthavong, Q. Ge, J. Tu, Numerical investigation of particle transport and inhalation using standing thermal manikins, Build. Environ. 60 (2013) 116–125. [18] D.N. Sørensen, L.K. Voigt, Modelling flow and heat transfer around a seated human body by computational fluid dynamics, Build. Environ. 38 (6) (2003) 753–762. [19] D. Marr, Velocity Measurements in Breathing Zone of a Moving Thermal Manikin within the Indoor Environment Ph.D. Thesis, Syracuse University, New York, 2007. [20] F. Lien, G. Kalitzin, Computations of transonic flow with the V2-F turbulence model, Int. J. Heat Fluid Flow 22 (2001) 53–61. [21] L. Davidson, P.V. Nielsen, A. Sveningsson, Modification of the V2F model for computing the flow in a 3D wall jet, Turbul. Heat Mass Transfer 4 (2003) 577– 584.
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933 [22] M. Abdolzadeh, M.A. Mehraian, A. Soltani, Numerical study to predict the particle deposition under the influence of operating forces on a tilted surface in the turbulent flow, Adv. Powder Technol. 22 (3) (2011) 405–415. [23] M. Abdolzadeh, M.A. Mehraian, Combined effect of thermophoretic force and other influencing parameters on the particle deposition rate on a tilted rough surface, Int. J. Therm. Sci. 50 (6) (2011) 954–964. [24] A. Li, G. Ahmadi, Dispersion and deposition of spherical particles from point sources in turbulent channel flow, Aerosol Sci. Technol. 16 (1992) 209–226. [25] Y. Hardalupas, A. Taylor, On the measurement of particle concentration near a stagnation point, Exp. Fluids 8 (1) (1998) 113–118. [26] J. Zhu, R. Rudoff, E. Bachalo, W. Bachalo, Number density and mass flux measurements using the phase Doppler particle analyzer in reacting and nonreacting swirling flows, in: AIAA, Aerospace Sciences Meeting, 1993.
933
[27] A.C.K. Lai, F.Z. Chen, Comparison of a new Eulerian model with a modified Lagrangian approach for particle distribution and deposition indoors, Atmos. Environ. 41 (25) (2007) 5249–5256. [28] D. Marr, T. Khan, M. Glauser, H. Higuchi, J. Zhang, On particle image velocimetry (PIV) measurements in the breathing zone of a thermal breathing manikin, Trans. – Am. Soc. Heat. Refrig. Air Condition. Eng. 111 (2005) 299–305. [29] R.H. Mohammed, Numerical investigation of displacement ventilation effectiveness, Int. J. Mech. Aerosp. Ind. Mech. Eng. 8 (2) (2014) 260–265. [30] T. Yang, P.C. Cropper, M.J. Cook, R. Yousaf, D. Fiala, L. Le, A new simulation system to predict human-environment thermal interactions in naturally ventilated buildings, in: Proceedings of the 10th International Conference on Building Simulation, Institute of Energy and Sustainable Development, De Montfort University, Division of Building Physics (ftba), Universität Karlsruhe, Englerstr, vol. 3, 2007, pp. 751–756.
Contents lists available at ScienceDirect
Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng
Research Paper
Computational modeling of particle transport and distribution emitted from a Laserjet printer in a ventilated room with different ventilation configurations Mehrzad Ansaripour, Morteza Abdolzadeh ⇑, Saleh Sargazizadeh Department of Mechanical Engineering, Graduate University of Advanced Technology, Kerman, Iran
h i g h l i g h t s The distribution of emitted particles form a laserjet printer was studied in the breathing zone. Effects of different ventilation configurations on the breathing zone concentration were investigated. Mixing ventilation system has a low mean particle concentration in the breathing zone.
a r t i c l e
i n f o
Article history: Received 3 February 2016 Revised 25 April 2016 Accepted 25 April 2016 Available online 26 April 2016 Keywords: Printer Ventilation Heated manikin Transport Particle Distribution
a b s t r a c t In the present research, computational modeling of particle transport and distribution emitted from a Laserjet printer was carried out in a ventilated room. A seated manikin was integrated into the study room and the manikin was evaluated in two cases: heated and unheated. Effects of different ventilation configurations of the room on the particle distribution were studied, including three displacement ventilation systems and a mixing ventilation system. The printer was located on different sides of the manikin and the particle concentrations in the breathing zone of the manikin due to the printer’s particles were evaluated in all the ventilation configurations. The averaged particle concentration in the breathing zone of the manikin was calculated and validated with the experimental and numerical data available in the literature. The results of the present study showed that in case of the heated manikin, the particle concentration due to the printer pollutants is significant in the breathing zone of the manikin. The results also showed that when the printer is located on the front side of the manikin, the particle concentration in the breathing zone is quite high in most of the used ventilation configurations. Furthermore, it was found that the mixing ventilation system has a lower mean particle concentration in the breathing zone compared to the most displacement ventilation systems. Ó 2016 Elsevier Ltd. All rights reserved.
1. Introduction Nowadays, many people are spending the majority of their day times in indoor spaces and are highly affected by the emitting particles released from copier machines and printers [1,2]. The electronics and computer engineering systems have been extensively used in the mankind life since their early development. These systems emit particles in indoor places and are known as an active source of particle generation as these systems, mostly release volatile and semi-volatile particles while they are working. ⇑ Corresponding author at: Department of Mechanical Engineering, Graduate University of Advanced Technology, End of Haft Bagh Highway, Kerman, Iran. E-mail addresses: [email protected], [email protected] (M. Abdolzadeh). http://dx.doi.org/10.1016/j.applthermaleng.2016.04.137 1359-4311/Ó 2016 Elsevier Ltd. All rights reserved.
These particles have different patterns and effects on the breathing zone of the human body based on the ventilation configurations and the location of a printer in rooms. These matters are very important to select the right ventilation systems and also the position of the printer in the room. The past studies [3,4] have indicated a tight relationship between the level of emitting pollutant particles and the adverse health effects such as early death and hospitalization (short term effects) plus lung cancer and cardiovascular diseases (long term effects). Indoor air quality (IAQ) is highly dependent on the number of particles penetrating into the indoor places from outside or inside spaces. In recent years, it has been indicated that the particles emitted from printers affect the indoor air quality of offices [5,6]. General characteristics of printer’s emissions like particle concentration and particle deposition rate can be experimentally
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
921
Nomenclature Ain C C0 Cc Cva Cpa d Gi g k nj n N p Rep S ti Tf T T1 tp u, v, w
inlet register area (m2) particle concentration (kg/m3) inlet particle concentration (kg/m3) Cunningham coefficient volume averaged concentration (kg/m3) plane averaged particle number concentration (kg/m3) Particle diameter (lm) Gaussian random number with zero-mean gravitational acceleration (m/s2) turbulent kinetic energy (m2/s2) the stochastic phenomenon of the Brownian diffusion number of particles that move across the plane having an area of A number of injected particles the air pressure (pa) Reynolds number based on velocity of particles relative to air ratio of particle density to fluid density the particle residence time (s) fluid absolute temperature (K) the sampling time (s) ambient temperature (K) relaxation time (s) velocity components (m/s)
measured in an experimental enclosed box. However, this determination of particle transportation and distribution is quite hard to achieve. This issue essences using computational fluid dynamics (CFD) as a useful tool to help understanding of the emitted pollutant particle behavior better. So far, many studies have been experimentally carried out in order to clarify the printer emission characteristics. For instance, Lee et al. investigated the emissions rate of pollutants from different types of office equipment. They showed that the emissions of ozone and VOC in laser printers are significantly higher than that of ink-jet printers [7]. Kagi et al. monitored the air contamination released from a laser printer/ ink-jet printer in a room. Their results confirmed an increase of the ozone concentration and ultrafine particle numbers in the printing processes [8]. He conducted an experiment and measured particle number concentrations and PM2.5 emissions from printers in a large open-plan office. They revealed that the particles generated by printers can significantly affect the levels of submicrometer particle number concentration in the office [9]. Hugo et al. reviewed available information on emission rates and also ambient concentrations of various pollutants which were related to office equipment use. The evaluated office equipments were computers (desktops and notebooks), printers (laser, ink-jet and all-in-one machines), and photocopier machines. They identified the toxicological substances significant in order to prepare a guide for evaluating their potential importance with respect to human exposures [5]. Morawska et al. carried out an experimental research which determined the particle composition, particle formation mechanism, and emission rate of Laserjet printers. They indicated that the emission rates of ultrafine particles of the printers are directly due to the Fuser temperature. They also showed that the particles are volatile and have a secondary nature, being formed in the air from volatile organic compounds originating from both the paper and hot toner [6]. Byeon and Kim investigated particle emissions for commercial color laser printers working under different printing speeds in an experimental chamber. They showed that the average particle number concentration is inversely proportional to the printing speed [10].
vP
V xi
v 02F
the particle velocity at the inlet register (s) measurement volume (m3) particle position (m) squared airflow fluctuation velocity normal to the wall (m2/s2)
Greek symbols qf fluid density (kg/m3) e Turbulent kinetic energy dissipation rate l fluid viscosity (kg/m s) k mean free path of the air molecules (lm) tt air flow turbulent viscosity (m2/s) Subscript m w in p f
mean wall inlet particle phase fluid
Superscript + dimensionless Reynolds averaging
A series of studies have focused on particle transport and distribution when a manikin was present in a room. For instance, Spitzer [11] and Spitzer et al. [12] carried out some experiments to study the effect of particle motion on the breathing zone of a seated breathing manikin. They revealed that the particle’s motion significantly affects the particle concentration of the breathing zone. Melikov and Kaczmarczyk [13] investigated the importance of the breathing zone of a thermal manikin when the indoor particles are inhaled. Rim and Novolselka investigated the airflow in the vicinity of a human body. They considered the effects of respiration on the breathing zone concentration of particulate and gaseous pollutants, and inhalation exposure in relation to source position and overall airflow patterns. They indicated that the overall airflow pattern influences the inhaled particle concentrations. They also revealed that highly mixed airflow in the space creates relatively uniform concentration patterns in the vicinity of the occupant. However, they also showed that the occupant thermal plume makes non-uniform concentration patterns [14]. Zukowska et al. studied several effects such as thermal insulation, the design of clothing and the chair, the blocking effect of tables on the thermal plume generated above a seated thermal manikin in a chamber [15]. Salmanzadeh et al. studied the buoyancy driven thermal plume near a sitting heated manikin. They showed that a high concentration of suspended particles in the breathing zone is seen due to the thermal plume flow created by the temperature gradient adjacent to the body [16]. Li et al. investigated effect of thermal manikin position on the characteristics of particle transport and inhalation. They revealed that the manikin orientation has a significant impact on the characteristics of particle transport and inhalation. They showed that for an occupant standing with its back towards the horizontal airflow, a little change in the leg posture can lead to an obvious variation in the source location of inhaled particles [17]. In the present study, particle transport and distribution emitted from a Laserjet printer in a ventilated room, which is scarce in the past studies, were computationally simulated using computational fluid dynamics. Combined Eulerian and Langragian methods were
922
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
applied to simulate the airflow field and the printer particle motion in the room. The printer was considered as the sole source of particle generation inside the room. A seated manikin was integrated into the study room and in order to take into account the thermal plume generated in the vicinity of the manikin body, it was evaluated in two cases: heated and unheated. Different ventilation configurations for the room were studied, including three displacement systems and a mixing ventilation system. The printer was located on different sides of the heated manikin and then the particle concentration was evaluated in the breathing zone of the manikin in all the ventilation configurations. The fluid flow and particle motion simulations were validated by Sorenson and his co-worker study [18] and Mar’s study [19], respectively. This study provides useful information on a printer emission distribution in a ventilated room with a seated manikin inside alongside with influence of printer location on the particle concentration in the breathing zone of the heated manikin to find the best location of the printer in the room. 2. System description Fig. 1 shows the schematic of the ventilated room used in this research. A cubicle with dimensions of 1.8 2.2 2.2 m was chosen and a seated female manikin was placed at the middle of the cubicle. It should be mentioned that the manikin geometry was borrowed from the database (http://www.ie.dtu.dk/manikin) addressed in Sorenson and Voigt study [18]. A Laserjet printer was used in this study and it was located 0.4 m away from the manikin and 0.75 m from the ground. To evaluate particle concentration in the breathing zone, an area of 0.07 0.07 m2 was selected in the front of manikin face and the mean concentration of passed particles across this area was calculated. The emission of printer particles was considered as a surface injecting source and released from an area of 0.09 0.09 m2 above the printer
head. The particle phase was assumed dilute. In the present CFD analysis, the room was studied with four different ventilation configurations, including three displacement ventilation systems as well as a mixing ventilation system shown in Figs. 1 and 2 and given in Table 1. 3. Governing equations and numerical methods 3.1. Fluid flow phase The airflow in the cubicle was simulated using the v2–f turbulence equations [20,21] as well as the energy equation. The model formulation has the following general form:
q
@/ @/ @ @/ j ¼ S/ þ qu C/;eff @t @xj @xj @xj
ð1Þ
where / represents the independent flow variables, C/;eff the effective diffusion coefficient, S/ the source term, q the flow density and the bars denote the Reynolds averaging. In Table 2 the mathematical form of each transport equation of the v2–f model are summarized. p is the air pressure, lt the turbulent viscosity, S the rate of strain, f a part of the v02 source term and Tl the turbulent time scale. The appropriate boundary conditions of turbulence variables near the walls are as follows:
k ¼ v 02 ¼ 0;
e ¼ 2t
k y2p
ð2Þ
yp is the distance from the cell center to the wall. In this study, commercial CFD software, FLUENT (version 6.2), was used to predict the turbulent airflow. The v2–f model used in this study is based on Davidson et al. [21] study Turbulent intensity, temperature, and velocity were considered 30%, 20 °C, and 0.2 m/s, respectively, in the inlet registers. The manikin body’s
Fig. 1. Sketch of the system studied in the present study.
923
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Fig. 2. Different ventilation configurations used in the present study.
Table 1 Configurations of different ventilation systems used in this study.
Table 3 Particle characteristics released from the printer. N0 (Particle/s)
Mixing ventilation system System I
Displacement ventilation system System II
System III
System IV
Inlet and outlet 4
Inlet and outlet 3
Inlet and outlet 2
Inlet and outlet 1
temperature and the temperature of cubicle walls were taken 31 °C and 19.75 °C, respectively. The pressure outlet boundary condition was given in the outlet registers of the cubicle. The manikin was considered in two cases: heated and unheated. The buoyancy movement due to the generated thermal plume was taken into account in the particle distribution calculation. This has been carried out taking the manikin as a constant temperature body which its temperature is higher than the surrounding air. Note, the impact of buoyant air movement was transferred to the particle phase by calculating the air velocity in the vicinity of the manikin and applying it on the particles. An unstructured grid (tetrahedral cell topology) was applied for surrounding air of the manikin. To resolve the boundary layer around the manikin, fine meshes were created at the surface of the manikin with an initial height of 0:2 mm, and a growth rate of 1.13. The energy equation was not solved in the unheated case as the flow was isotherm. It should be pointed out, these boundary conditions are the same in all the ventilation systems considered in this study. The unstructured mesh and the finite volume method as well as the SIMPLE algorithm were used to solve the governing equations. Grid
510
9
dp (lm)
qp (kg/m3)
Vp (m/s)
0.05
2000
0.2
dependency analysis of the computational domain was carried out and a computational mesh containing about 1.13 106 cells showed a sufficient accuracy for continuing the analysis, Table 4. 3.2. Particle phase So far, several experiments for determination of printer particle characteristics such as rate of emitting particles, particle diameter, particle density, and particle temperature have been carried out in the past studies [6,10]. The particle characteristics released from the printer are given in Table 3. The emission of particles into the cubicle was considered with a time interval of 3 min for the printing process. A concentration of 5 109 particles-cm3 was considered as the emission source of the cubicle released from the printer [10]. It was reported that when the printing is getting started an average particle size of 50 nm (50 prints/min) comes out of the printing process. It also should be pointed out that due to the temperature difference between the hot air generated in the printer and the surrounding air, the emitted particles move upward from the printer head. To take into account this fact, it was assumed that the particles are emitted into the air with an initial velocity of 0.2 m/s. It should be stated that this velocity
Table 2 Coefficients and source terms in Eq. (1). Name of conservation equation
Independent flow variable /
Effective diffusion coefficient C/;eff
Source term S/
Continuity X-Component of momentum
1 U
0
0
Y-Component of momentum
V
tt þ t tt þ t
Z-Component of momentum
W
tt þ t
Energy Turbulent kinetic energy (k) Turbulent kinetic energy dissipation rate (e) Wall normal turbulence fluctuation to kinetic energy (uÞ
Tf K E
kf þ tt=rT tt =rk;t þ t tt =re;t þ t tt =ru þ t
ðv02 =kÞ
pffiffiffiffiffiffiffiffiffiffi L2 Da a ¼ 1; Gk ¼ tt S2 ; S ¼ Sij Sij ; Su ¼ ð1 ap Þf w þ ap f h Gk u=k. pffiffi f h ¼ T1l C 1 1 þ Gek ðu 2=3Þ; f w ¼ uke T l ¼ max ke ; C T me . 3=2 3=4 L ¼ C L max k e ; C g te1=4 ; P k ¼ 2C l v02 TS2ij . qffiffiffi tt ¼ C l ; ku T l ; C 0e1 ¼ 1:44 1 þ 0:04ð1 ap Þ u1 . C e2 ¼ 1:83; C 1 ¼ 1:7; C 2 ¼ 1:2; C l ¼ 0:22; C L ¼ 0:161; C g ¼ 90; C T ¼ 6; rk;t ¼ 1; re;t ¼ 1:22; ru;t ¼ 1; p ¼ 3.
@ q1 @p @x þ @x @ q1 @p @y þ @x
@u
@ @v @ @w tt @u @x þ @y tt @x þ @z ðtt @z Þ
@ q1 @p @z bgðT f T 1 Þ þ @y
0 Gk e ðC 0e1 Gk C e2 eÞ=T l
@k @ u a t þ tt =rk;t Þ @x þ Su j @xj
2 ð p k
tt @x þ @y@ tt @@yv þ @z@ tt @w @z
@ @w tt @@yv þ @x@ tt @u @y þ @z tt @z
924
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Table 4 Checking the solution gride dependency. Cell number
54,000
434,000
691,700
922,147
1,129,885*
1,357,557
Skin friction coefficient of the manikin body Convective heat transfer coefficient in the vicinity of the manikin (W/m2 K) Air Temperature, 5cm away from the manikin face (K)
0.000182 1.14 293.88
0.000383 1.82 294.17
0.000878 2.67 294.33
0.000959 2.62 294.38
0.00232 2.44 294.57
0.00227 2.38 294.54
*
The optimum mesh number.
was selected based on the maximum air velocity created above the printer head due to the released heat of the printer while is printing and it was found doing a separate simulation of the air above the printer. The released heat of the printer was assumed 40 W. 3.2.1. Mathematical modeling of particle motion and particle concentration distribution The Lagrangian point of view was used to model particle transport in the air. The following equations were used to simulate movement of spherical particles: p
dxj ¼ upj dt
ð3Þ
p 5:188v 1=2 d 1 þ 0:15Re0:687 duj d ij ujf upj þ ujf upj ¼ 1=4 dt sp Sdðdlk dkl Þ
1 þ nj ðtÞ þ 1 g s i
ð4Þ
where ujf ¼ ui þ u0j which ui is the mean flow velocity at the particle location, u0j is the flow fluctuation velocity, upj is the velocity of particles at the center of the particles, xi is the particle position, t is time, d is the particle diameter, S is the ratio of particle density to fluid density, and gi is the gravitational acceleration. Re ¼ ju f up jd=v is the particle Reynolds number based on the
Fig. 3. Velocity distribution (m/s) in the mid plane of the cubicle. (a) Unheated manikin. (b) Heated manikin in System (IV).
925
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Velocity
Velocity
Temperature (a)
Temperature (b)
Fig. 4. Vertical Velocity (m/s) and Temperature (°C) distributions around the manikin body (a) present study (b) Sorenson and Voigt [18] study.
flow-particle slip velocity. The first term on the right-hand side of Eq. (4) stands for the Stokes drag. Here, sp is the Stokes relaxation time and is as follows [22,23]:
sp ¼
2
d SC c 18v
ð5Þ
Cc is the Stokes–Cunningham correction factor which modifies the drag force exerted to ultrafine particles due to slip and is:
Cc ¼ 1 þ
k 0:8 2:514 þ 0:55d=k d e
ð6Þ
The second term on the right right-hand side of Eq. (4) presents the contribution of the Saffman lift force. The third term in Eq. (4), nj(t), represents the stochastic phenomenon of the Brownian diffusion. This force is modeled by a Gaussian random number with zero-mean, unit variance, Gi, as [24]:
nj ðtÞ ¼ Gi
216
p
vr
T q f d5 S2 C c Dt
ð7Þ
The fourth term in Eq. (4) is particle gravitational force. To calculate the particle concentration in the room as well as the concentration in the breathing zone of the manikin due to the printer particle generation, plane and volume averaged particle number concentrations are obtained. The method of Hardalupas and Taylor [25] implemented by Zhu et al. [26] was used to calculate the volume averaged concentration. Based on this method, the particle number concentration is as follows:
Pn Cva ¼
i¼1 t i
ð8Þ
VT
where n is the number of particles that move across the measurement volume V, and ti is the particle residence time in the
-0.1
(a)
!1=2
(b)
-0.05
0
y
0.05
0.1
(c)
Fig. 5. Vertical velocity (m/s) distribution above the manikin head (a) experimental study [18] (b) numerical study [18] (c) present simulation.
926
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
(a)
Present Study Experiment [27]
(b) Lai and Chen [27] Empirical Equaon [27] Present Study
(c) Fig. 6. (a) Experimental chamber, (b) comparison of particle concentration in the mid-plane of chamber at different x-locations and (c) deposition fraction in the chamber vs. different particle sizes with the experimental data [27].
measurement volume, and T is the sampling time. The plane averaged particle number concentration, Cpa, is calculated as follows:
C pa
Pn 1=v pi ¼ i¼1 AT
ð9Þ
the calculated concentrations in the breathing zone. The normalized volume averaged concentration is given as:
Pn ti =V C þv a ¼ i¼1 t N=Ain v in
ð10Þ
The plane averaged concentration is as follows: where n is the number of particles that move across the plane having an area of A with a normal velocity vp. It should be stated that the average concentration at the inlet was used to normalize
C þpa
Pn p A i¼1 1=v i ¼ N=Ain v tin
ð11Þ
927
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
(a)
Manikin head V(m/s)
V(m/s)
V(m/s)
[19]
(b)
(c)
[16]
(d)
Fig. 7. (a) The room and the manikin position used in the experimental study [28] and the computational study [19], vertical velocity distribution above the manikin head (b) present study (Sorenson and Voigt’s Manikin) (c) experimental study (Mar’s Manikin) [19] (c) computational study (Mar’s Manikin) [16].
where N is number of injected particles and velocity at the inlet register with an area of Ain.
vP
is the particle
Numerical Study[16] Experiment [19] Present study
The particle equation of motion was solved using the discrete phase of FLUENT software. The concentration equations listed above were solved using a homemade computer code written in MATLAB. This code was later linked to the discrete phase model of FLUENT to obtain the particle concentration in the breathing zone.
4. Results and discussion 4.1. Fluid flow analysis
Fig. 8. Comparison of normalized plane average concentrations of the manikin breathing zone, between the present simulation and the numerical [16] and the experimental studies [19].
In this section, first, the fluid flow inside the cubicle is evaluated. The fluid flow was investigated in two cases: heated and unheated manikins. Fig. 3(a) shows the velocity distribution inside the cubicle when the manikin is unheated. In this case, the energy equation is not solved. As shown in this figure, the fluid flow entered from the inlet register is directly moving upward and the maximum velocity location is away from the manikin. In case of the heated manikin, the buoyancy force is added to the momentum equation due to the temperature difference between the manikin and the ambient air. In this case, shown in Fig. 3(b), the maximum air velocity is seen above the manikin head and a secondary flow is created over the head. To check the simulation results accuracy,
928
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Unheated
Heated
t=25s
t=75s
t=130s Fig. 9. Particle dispersion in the cubicle at different time histories for the unheated and heated manikins in System IV.
the present study was compared with Sorenson and Voigt [18] numerical and experimental results. It should be mentioned that in their study the inlet was on the bottom side and the outlet was from the cubicle ceiling. The flow velocity was 0.02 m/s and its turbulent intensity was 30%. The temperatures of the walls and the manikin were assumed equal. It should be mentioned that the Sorenson geometry as well as the its boundary conditions were simulated and then the results of the simulation were compared with the measured data The comparisons of the velocity and temperature around the manikin are shown in Fig. 4(a) and (b). As shown in these figures, the present study predicts the velocity and temperature with a sufficient accuracy compared to the Sorenson et al. numerical results. Fig. 5 shows the comparison of the vertical flow velocity above the manikin head with the numerical and experimental results of Sorenson and his coworkers. As shown in
this figure, the present simulation predicts the vertical velocity with a sufficient accuracy compared to the experimental data. 4.2. Particle trajectories and distribution 4.2.1. Validation of the particle model with no manikin In this section, the particle phase is validated using an experimental data which were measured in an experimental chamber [27] The dimensions of the chamber were 0.4 0.4 0.8 m (Fig. 6(a)) and the inlet velocity was 0.225 m/s. Particle diameter and density were 10 lm and 1400 kg/m3, respectively, and the particles were released from the inlet register. Fig. 6(b) shows the comparison of particle concentrations vs. the chamber height in different x locations of the chamber. As shown in this figure, the v2–f model along with the particle model predict the particle distri-
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Fig. 10. Normal particle concentration in the breathing zone for heated and heated manikins.
bution with a reasonable accuracy. Fig. 6(c) shows the comparison of deposition fractions in the experimental chamber using the present numerical model and the experimental data in the particle range of 0.01–10 lm. These figures show that the accuracy of the present numerical model is sufficient for pursuing the goal of present simulation.
4.2.2. Validation of the particle model with the manikin In this section, the particle concentration distribution in the breathing zone of the manikin is compared with the computational
929
and experimental studies [16,19] conducted in the past studies. The inlet velocity was 0.2 m/s. Particle diameter and density were 1 lm and 2000 kg/m3, respectively, and the particles were released from the inlet register. Fig. 7(a) shows the study room and the corresponding ventilation systems which were used in this study. It should be mentioned that their ventilation system is the same as System IV with the equal dimensions used in the present study. As the manikin used in the present study is a female manikin and in those studies is a male manikin, it is first required to compare the velocity distributions of all the studies in order to check out the likely difference of the flow characteristics around the manikin. It should be stated that in that two studies [16,19] as well as present study, the manikins were considered as heated manikins and their body temperature was taken 32.2 °C. The air flow characteristics at the inlet register in all the studies are the same as information given in Section 3. Fig. 7(b)–(d) shows the velocity magnitude above the manikin head computed in the present study with female manikin and Salmanzadeh et al. study [16] and Mar and Mar et al. studies [28,19] with the male manikin. As shown in this figure, the velocity distribution above the manikin head is close to the experimental study and this means that the difference between the present study and those two studies [16,19] in term of manikin gender is negligible as the present simulation predicts the flow velocity with a reasonable accuracy. These figures also show
Fig. 11. Velocity distributions (m/s) in the mid plane of cubicle in Systems (a) III (b) II and (c) I.
930
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Normalized Concentaron
Fig. 12. Normalized particle concentration of the breathing zone in all the ventilation systems – printer located in the front of the manikin.
1.4
System IV
System III
System II
System I
1.2 1 0.8 0.6 0.4 0.2 0
BACK
FRONT
LEFT
RIGHT
Fig. 14. Normalized particle concentration in the breathing zone for different printer positions in all the ventilation systems (I, II, III, and IV).
Fig. 13. Different printer locations around the manikin.
that the velocity distribution of the present study is more similar to the experimental study compared to Slamanzedh et al. [16] study. Fig. 8 shows the average particle concentration in the plane of the breathing zone of the manikin located at different distances of the manikin’s face. In all the studies, 10,000 particles with 1 lm diameter were injected from the inlet register for 10 min in the steady state condition. Fig. 8 shows that the present study predicts the particle concentration with a reasonable accuracy compared to the experimental study. However, there are still some differences between the present simulation and the experimental date at some distances. These differences are due to: the experimental data which were measured while the manikin was breathing, which was not taken into account in this study and also the likely minor differences between the shape of the applied manikin in the present study and Mar’s study. However, differences between the measured and the simulated data for the first two points are less than 10% and it should be mentioned that Marr [19] reported his measured data with 15% uncertainty. 4.2.3. Particle concentration distribution due to the printer emission The particle concentration distributions due to the printer pollutants for the heated and unheated manikins with the ventilation
system (IV) at different time histories of particle emission are shown and compared in Fig. 9. As shown in this figure, the breathing zone is less affected in case of the unheated manikin and this is condition does not exist when the manikin is considered as a heat generating body. In this case, the breathing zone is significantly affected due to the emitted particles and this issue is more pronounced at the higher time histories of emission. This figure also shows that the particle accumulations in the breathing zone of the unheated case at the lower time histories are not significant, but in the heated case, the breathing zone from the beginning of particle emission is in a bad condition. Comparison of normal particle concentrations in the breathing zone of the manikin for the two above mentioned cases with 180 s passed time, are shown in Fig. 10. As shown in this figure, the average particle concentration of the heated manikin is 6 times larger than the unheated one. It is also revealed that the location of printer highly affects the quantity of particle concentration in the breathing zone and needs more attention and consideration. 4.2.4. Effect of different ventilation configurations on particle concentration of the breathing zone 4.2.4.1. Printer located in front of the manikin. In this section, the three other ventilation configurations described in Section 2 are evaluated when the printer is located in the front of the manikin. The velocity distributions in the mid plane of the cubicle are shown in Fig. 11(a), (b), and (c) for systems III, II, and I, respectively. As shown in these figures as well as Fig. 4, the maximum velocity in
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
931
Fig. 15. Velocity distributions (a) in the mid plane of cubicle in x direction (b) the plane in the right of the manikin (c) the plane in the left of the manikin.
the breathing zone among all the systems is seen in the system (IV) (Fig. 4). This is due to the inlet air register which is located in the front of manikin and creates the maximum air movement in the breathing zone. This speed is decreased in systems III, II, and I, respectively. System III also has a high air speed in the breathing zone, but still lower than system IV as the air register in this system does not directly blow the air through the breathing zone area. System (I) has the lowest air movement in the breathing zone as the inlet register is located in the back side of manikin close to the ground and in this case the air movement in the breathing zone is mostly due to the thermal heat plume generated around the manikin body. The particle concentration distributions in the breathing zone of all the configurations are shown in Fig. 12. As it was expected from the flow analysis of all the systems and shown in this figure, system IV and system I have the highest and lowest particle concentrations, respectively, in the breathing zone of the manikin. This matter is mostly due to the air speed in the breathing zone. System IV has the maximum particle concentration in the breathing zone due to the air register location which is the worst place for the inlet register among all the systems. System I show a good performance to remove the particle released from the front of manikin without directing them toward the breathing zone. This fact is due to the location of inlet air register on the back side of the manikin which makes the air flow to
move above the manikin head and suck the particle from the printer head and deliver them to the outlet register. 4.2.4.2. Printer located on the other sides of the manikin. In this section, the printer is located on the other sides of the manikin (Fig. 13) and then the particle concentration of the breathing zone in each ventilation configuration is obtained and compared with one another in order to find the best printer location in the corresponding configuration. The particle concentrations of the breathing zone in all the configurations are shown in Fig. 14. As shown in this figure, the system (IV) has the maximum and minimum concentrations among all the configurations when the printer is located in the front and back sides of the manikin. This fact clearly says that the printer should be located in the back side of the manikin in System (IV) as in this case the released particles do not cross the breathing zone and make this area safe from the particle pollution. This figure also shows that system (I) has the maximum particle concentration when the printer is located on the right, left, and back sides of the manikin. The large particle concentration in the back side of the manikin is due to the printer location which directs the emitted particle into the air and they cross the breathing zone in the way of approaching the outlet register. It is also revealed that the right and left sides of the manikin also are not good places for the printer as the released particles from these
932
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933
Mean normal concentraon
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
System I
System IV
System II
System III
(a) Normalized cincentraon
0.9 0.8 0.7 0.6
into the study room and it was evaluated in two cases: heated and unheated. To find the best place of the printer with the lowest particle concentration of the breathing zone in the study room, the printer was located on different sides of the manikin and the breathing zone particle concentrations of the heated manikin were evaluated in all the ventilation configurations. The results of the present simulation show that the printer’s particle emission highly affects the enhancement of particle concentration in the breathing zone of the heated manikin. It was also revealed that when the printer is located in the back side of the heated manikin, the minimum particle concentration of the breathing zone is seen in all the ventilation configurations which suggests the best area of the printer location. This trend of the concentration in the breathing zone is completely opposite when the printer is located in front of the manikin. Furthermore, It was also concluded that the mixing ventilation system has a lower mean particle concentration in the breathing zone compared to the displacement ventilation systems.
0.5 0.4
References
0.3 0.2 0.1 0
BACK
RIGHT
LEFT
FRONT
(b) Fig. 16. Mean normalized concentration of the breathing zone based on (a) the ventilation configurations (b) the printer locations.
places, place the breathing zone at more risk compared to the back side of the manikin. All these observations suggest that the best place of the printer in System (I) is the front side of the manikin. It should be pointed out that the symmetry condition of the fluid flow due to the buoyancy effect created in the vicinity of manikin leg is not held between the right and the left sides of the manikin body as shown in Fig. 15. This fact has also been reported in the past studies [15,29,30]. The unsymmetrical condition yields different particle concentration quantities in systems (I), (II), and (IV). However, the differences between the concentrations of the right and left sides in the above mentioned systems are negligible. Fig. 16(a) shows the mean normalized concentration in the breathing zone averaged over all the printer locations for each configuration. This figure states that the mixing ventilation system (system II) is more suitable than the displacement systems in case of particle emission in the breathing zone. It is also shown that the maximum normal concentration among all the displacement ventilation systems happens to system I. It is also revealed that the best displacement system is System (III) as in this case the manikin is rotated 90° with respect to the inlet register. Fig. 16 (b) shows the mean particle concentration which is the average of particle concentration of all the systems for all the manikin sides. As shown in this figure, the back and front sides of the manikin have the lowest and highest particle concentrations in the breathing zone, respectively. It means that the front side of the manikin in all the systems except system (I) is the worst place for the printer. The right and left sides of the manikin also have high particle concentrations in the breathing zone and this also shows that these places are not good places for the printer.
5. Conclusion In this study, the pollutant particles emitted from a Laserjet printer were computationally simulated in a ventilated room with four ventilation configurations. A seated manikin was integrated
[1] R.D. Brook, S. Rajagopalan, C.A. Pope, et al., Particulate matter air pollution and cardiovascular disease: an update to the scientific statement from the American heart association, Circulation 121 (2010) 2331–2378. [2] S.S. Lim, T. Vos, A.D. Flaxman, et al., A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010, Lancet 380 (2012) 2224–2260. [3] C. Iribarren, I.S. Tekawa, S. Sidney, G.D. Friedman, Effect of cigar smoking on the risk of cardiovascular disease, chronic obstructive pulmonary disease, and cancer in men, New Engl. J. Med. 340 (1999) 1773–1780. [4] J. Guo, T. Kauppinen, P. Kyyronen, P. Heikkila, M.L. Lindbohm, E. Pukkala, Risk of esophageal, ovarian, testicular, kidney and bladder cancers and leukemia among finnish workers exposed to diesel or gasoline engine exhaust, Int. J. Cancer 111 (2004) 286–292. [5] Hugo Destaillats Randy, L. Maddalena, Brett C. Singer, Alfred T. Hodgson, Thomas E. McKone, Indoor pollutants emitted by office equipment: a review of reported data and information needs, Atmos. Environ. 42 (7) (2008) 1371– 1388. [6] L. Morawska, C. He, G. Johnson, R. Jayaratne, T. Salthammer, H. Wang, E. Uhde, T. Bostrom, R. Modini, G. Ayoko, P. Mcgarry, M. Wensing, Laser Printers : A Source of Nanoparticles in Indoor Office Environments. No December, 5–9, 2009. [7] S.C. Lee, S. Lam, H.K. Fai, Characterization of VOCs, ozone, and PM 10 emissions from office equipment in an environmental chamber, Build. Environ. 36 (2001) 837–842. [8] N. Kagi, S. Fujii, Y. Horiba, N. Namiki, Y. Ohtani, H. Emi, H. Tamura, Y.S. Kim, Indoor air quality for chemical and ultrafine particle contaminants from printers, Build. Environ. 42 (5) (2007) 1949–1954. [9] C. He, Office particle emission characteristics of office printers CONGRONG, Environ. Sci. Technol. 6039–6045 (2007). [10] J.H. Byeon, J.W. Kim, Particle emission from laser printers with different printing speeds, Atmos. Environ. 54 (2012) 272–276. [11] I.M. Spitzer, Experimental Aerosol Characterization in the Indoor Environment Using Phase Doppler Anemometry Master’s Thesis, Syracuse University, 2006. [12] I.M. Spitzer, D.M. Marr, M.N. Glauser, Impact of manikin motion on particle transport in the breathing zone, J. Aerosol Sci. 41 (2010) 373–383. [13] A. Melikov, J. Kaczmarczyk, Measurement and prediction of indoor air quality using a breathing thermal manikin, Indoor Air 17 (1) (2007) 50–59. [14] Donghyun Rim, Atila Novosela, Transport of particulate and gaseous pollutants in the vicinity of a human body, Build. Environ. 44 (2009) 1840–1849. [15] D. Zukowska, A. Melikov, Z. Popiolek, Impact of personal factors and furniture arrangement on the thermal plume above a sitting occupant, Build. Environ. 49 (104–116) (2011) 2012. [16] M. Salmanzadeh, G. Zahedi, G. Ahmadi, D.R. Marr, M. Glauser, Computational modeling of effects of thermal plume adjacent to the body on the indoor airflow and particle transport, J. Aerosol Sci. 53 (2012) 29–39. [17] X. Li, K. Inthavong, Q. Ge, J. Tu, Numerical investigation of particle transport and inhalation using standing thermal manikins, Build. Environ. 60 (2013) 116–125. [18] D.N. Sørensen, L.K. Voigt, Modelling flow and heat transfer around a seated human body by computational fluid dynamics, Build. Environ. 38 (6) (2003) 753–762. [19] D. Marr, Velocity Measurements in Breathing Zone of a Moving Thermal Manikin within the Indoor Environment Ph.D. Thesis, Syracuse University, New York, 2007. [20] F. Lien, G. Kalitzin, Computations of transonic flow with the V2-F turbulence model, Int. J. Heat Fluid Flow 22 (2001) 53–61. [21] L. Davidson, P.V. Nielsen, A. Sveningsson, Modification of the V2F model for computing the flow in a 3D wall jet, Turbul. Heat Mass Transfer 4 (2003) 577– 584.
M. Ansaripour et al. / Applied Thermal Engineering 103 (2016) 920–933 [22] M. Abdolzadeh, M.A. Mehraian, A. Soltani, Numerical study to predict the particle deposition under the influence of operating forces on a tilted surface in the turbulent flow, Adv. Powder Technol. 22 (3) (2011) 405–415. [23] M. Abdolzadeh, M.A. Mehraian, Combined effect of thermophoretic force and other influencing parameters on the particle deposition rate on a tilted rough surface, Int. J. Therm. Sci. 50 (6) (2011) 954–964. [24] A. Li, G. Ahmadi, Dispersion and deposition of spherical particles from point sources in turbulent channel flow, Aerosol Sci. Technol. 16 (1992) 209–226. [25] Y. Hardalupas, A. Taylor, On the measurement of particle concentration near a stagnation point, Exp. Fluids 8 (1) (1998) 113–118. [26] J. Zhu, R. Rudoff, E. Bachalo, W. Bachalo, Number density and mass flux measurements using the phase Doppler particle analyzer in reacting and nonreacting swirling flows, in: AIAA, Aerospace Sciences Meeting, 1993.
933
[27] A.C.K. Lai, F.Z. Chen, Comparison of a new Eulerian model with a modified Lagrangian approach for particle distribution and deposition indoors, Atmos. Environ. 41 (25) (2007) 5249–5256. [28] D. Marr, T. Khan, M. Glauser, H. Higuchi, J. Zhang, On particle image velocimetry (PIV) measurements in the breathing zone of a thermal breathing manikin, Trans. – Am. Soc. Heat. Refrig. Air Condition. Eng. 111 (2005) 299–305. [29] R.H. Mohammed, Numerical investigation of displacement ventilation effectiveness, Int. J. Mech. Aerosp. Ind. Mech. Eng. 8 (2) (2014) 260–265. [30] T. Yang, P.C. Cropper, M.J. Cook, R. Yousaf, D. Fiala, L. Le, A new simulation system to predict human-environment thermal interactions in naturally ventilated buildings, in: Proceedings of the 10th International Conference on Building Simulation, Institute of Energy and Sustainable Development, De Montfort University, Division of Building Physics (ftba), Universität Karlsruhe, Englerstr, vol. 3, 2007, pp. 751–756.