Sizing and life-cycle assessment of building integrated thermoelectric air cooling and photovoltaic wall system

Accepted Manuscript Sizing and life-cycle assessment of building integrated thermoelectric air cooling and photovoltaic wall system Kashif Irshad, Khairul Habib, Salem Algarni, Bidyut Baran Saha, Basharat Jamil PII: DOI: Reference:

S1359-4311(18)31906-9 https://doi.org/10.1016/j.applthermaleng.2019.03.027 ATE 13456

To appear in:

Applied Thermal Engineering

Received Date: Revised Date: Accepted Date:

27 March 2018 3 March 2019 6 March 2019

Please cite this article as: K. Irshad, K. Habib, S. Algarni, B. Baran Saha, B. Jamil, Sizing and life-cycle assessment of building integrated thermoelectric air cooling and photovoltaic wall system, Applied Thermal Engineering (2019), doi: https://doi.org/10.1016/j.applthermaleng.2019.03.027

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.

Sizing and life-cycle assessment of building integrated thermoelectric air cooling and photovoltaic wall system Kashif Irshad1*, Khairul Habib2, Salem Algarni3, Bidyut Baran Saha4,5, Basharat Jamil6 1

Center of Research Excellence in Renewable Energy (CoRERE), King Fahd University of Petroleum &Minerals, Dhahran, Saudi Arabia 2

Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak Darul Ridzuan, Malaysia 3

Department of Mechanical Engineering, King Khalid University P.O. Box 9004, Abha 61413, Saudi Arabia

4

International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan 5

Mechanical Engineering Department, Kyushu University 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

6

Heat Transfer and Solar Energy Laboratory, Department of Mechanical Engineering, Z.H. College of Engg. & Tech., Aligarh Muslim University, Aligarh-202002, India

Corresponding author, E-mail address: [email protected], [email protected] Abstract: This study presents a procedure for calculating the size and cost of integrating thermoelectric air cooling duct (TE-AD) and photovoltaic wall (PV-W) systems with test room in tropics. The investigation of economics and energy consumption was conducted, wherein three categories of air cooling systems-split air conditioner, Grid connected TE-AD system (G_TE-AD), and PV connected TE-AD system (PV_TE-AD) were compared. The sizes of the TE-AD system and PV system were determined based on the test room cooling load, sunshine duration, and daily electrical power required by the TE-AD system (kWh/day). The results obtained via life-cycle assessment (LCA) of the above systems suggested that the PV_TE-AD cooling system provides better economic and energy saving potential with better carbon emission reduction, compared to the other two systems. PV_TE-AD cooling system incurs operating costs of US$ 44.0 and US$ 151.0, lower than the G_TE-AD system and the split air conditioners, respectively. CO2 emission 1

reduction of PV_TE-AD system reached 60.24 tons, which was two times less than that of the G_TE-AD system. The payback period of the G_TE-AD system was 4.2 years, which was six months lower than that of the PV_TE-AD system owing to the additional initial cost of the PV system. Keywords: Thermoelectric module, Photovoltaic wall, Life-cycle assessment, carbon credit, Payback time Abbreviations APV AGlass B

: : :

photovoltaic cell area (m2) photovoltaic glazing area (m2) savings cost of the TE-AD system (US$)

C

:

investment cost of the TE-AD system (US$)

Cc

:

carbon credit earned (US$)

Cf Cg CP Cw d D Dw DG DV

: :

air duct friction factor specific heat of glass (J/kgK) specific heat of air (J/kgK) specific heat of wall (J/kgK) hydraulic diameter of air duct (m) depth of air duct (m) the wall thickness (m) the thickness of glass panel (m) diminishing value (US$)

E

: :

: : : : : :

total annual electrical energy units consumed (kWh/year)

EER

:

energy efficiency ratio

g G G’ GBR GDP

: : : : :

gravitational acceleration (m/s2) total solar radiation on the vertical plane (W/m2) geometric factor (area/length of TE element) (cm) surface beam radiation (W/m2 h) gross domestic product

GH GN GPV Grx GTR hco,

: : : : : :

hci

:

hnrwo

:

horizontal surface global solar radiation(W/m2 h) direct normal solar radiation (W/m2 h) solar radiation which arrives on the PV surface (W/m2) local Grashof number overall solar radiation falling on the surface (W/m2h) convective heat transfer coefficients on the outside surface of PV glass panel (W/m2 K) convective heat transfer coefficients on the inside surface of PV glass panel (W/m2K) radiation heat transfer coefficient on the outside surface 2

hnwi,

:

hnwo

:

hro,

:

hri

:

hrwo

:

hwo

:

hwi

:

i

:

of normal wall (W/m2 K) convective heat transfer coefficient on the inside surface of normal wall (W/m2 K) convective heat transfer coefficient on the outside surface of normal wall (W/m2 K) radiation heat transfer coefficients on the outside surface of PV glass panel (W/m2 K) radiation heat transfer coefficients on the inside surface of PV glass panel (W/m2 K) radiation heat transfer coefficient on the outside surface of PV wall (W/m2 K) convection heat transfer coefficients on the outside surface of PV wall (W/m2 K) convection heat transfer coefficients on the inside surface of PV wall (W/m2 K) interest rate

I

: : : :

current supply to thermoelectric module (A) module’s thermal conductance (W/K) height of PV wall (m) depth of room (m)

m M

: :

mass flow rate (kg/s) operation and maintenance cost every year (US$/year)

N

:

number of quantity

n nd Npv Nux Pi

: : : : :

life of system (year) diode quality factor number of cells connected in series local Nusselt number capital Cost (US$)

PRM

:

repair and maintenance cost (US$)

PReplace

:

replacement cost (US$)

Pr

:

Prandtl number

PS

:

present salvage value (US$)

PTE q Qcold QFH Qhot QJH QPEC QPEH RTE

: : : : : : : : :

power supplied to thermoelectric module (W) value of electron’s charge (-1.602 10-19 C) heat absorbed at cold surface (W) fourier heat heat released at hot surface (W) Joule heat Peltier cooling Peltier heating electrical resistance of module (  )

KTE L Lroom .

3

STE

: : :

Seebeck voltage of module (V/K) Thot-Tcold (K) cold side temperature (K)

Thot Ta TDB Tin Tnwo Tnwi To TP Te Tpn Tref TSKY Tw Two Twi Uj

: : : : : : : : : : : : : : : :

Va

:

hot side temperature (K) ambient temperature (K) dry-bulb temperature (K) indoor room temperature (K) normal wall outside surface temperature (K) normal wall inside surface temperature (K) air duct outlet temperature at the next time step (K) solar glass panel temperature (K) air duct temperature (K) P–N junction temperature (K) 298.15 (K) sky temperature (K) temperature of PV wall (K) temperature of outside surface of PV wall (K) temperature of inside surface of PV wall (K) overall heat transfer coefficient between interlayer and indoor room (W/m2 K) velocity of the air flow in the duct (m/s)

Vin

: : : : : : : : :

voltage (V) velocity of air exhausted into the room at the next time step (m/s) voltage at maximum power point (V) open circuit voltage wind velocity at the next time step (m/s) power consumption of fan (W) width of PV wall (m) width of the room (m) figure of merit (K-1)

 αpv αwall αnwall αwpv

: : : : :

αnpv

:

β Ɛ η0

: : : :

Seebeck coefficient (V/K) absorptivity of the PV cells absorptivity of the PV wall absorptivity of the normal wall equivalent absorptivity of the elements with PV cell on the glass panel equivalent absorptivity of the elements without PV cell on the glass panel heat expansion coefficient (K-1) ratio of PV cell coverage electrical efficiency at standard conditions thermal conductivity (W/ (cmK))

T Tcold

Vf Vmpp Voc Vw W w wroom Z Greek Symbol



4

λa g w μv μf ν 1 ,  2 ,  3 ρ

:

air thermal conductivity (W/mK)

: : : :

glass thermal conductivity (W/mK) wall thermal conductivity (W/mK) temperature coefficient of open circuit voltage (V/K) temperature coefficient of short circuit current (A/K) air kinematic viscosity (m2/s) emissivity factors humidity ratio air density (kg/m3)

: : :

a

:

g

: :

w σ

:

PV

: :

 φ x

: :

density of glass (kg/m3) density of wall (kg/m3) resistivity (  cm) transmissivity of the elements without solar cell on the glass panel transmissivity of the solar cell outside layers solar zenith and azimuth angle (°) measured value range

1. Introduction With the increase in temperature of the earth’s surface, the demand for cooling of buildings has increased abruptly [1]. Economic affordability among the middle socio-economic classes of developing countries has increased the use of air conditioners by 20% in recent years [2]. This alarming situation has increased the pressure on scientists to develop renewable alternative cooling systems that are economically viable and can provide thermal comfort to the occupants of buildings. The research on the integration of buildings with photovoltaic (PV) systems has been conducted by many researchers. The results obtained from the life-cycle cost analysis of PV systems integrated with buildings suggested that this system can reduce CO 2 emission and energy usage of buildings [3-4]. Nevertheless, building-integrated PV systems alone cannot deliver thermal comfort to people who live in regions such as the tropics owing to the consistently high humidity and temperature throughout the year. Therefore, integration of another system known as a thermoelectric module (TEM) together with a PV system can solve the environmental issues mentioned above; however, this concept was investigated for only a few climatic conditions. This was due to the low thermodynamic efficiency, coefficient of performance (COP), cooling capacity, and high initial prices of TEMs [5]. Abdul et al. [6] 5

developed and experimentally verified a moveable thermoelectric (TE) cooler powered by solar panels. The results revealed that the COP was 0.16 and the refrigeration temperature was diminished from 27 °C to 5 °C in approximately 44 min. However, this study was carried out in small scale under control environment. Also parameters, i.e. optimum input power to TEMs, air flow rate, orientation and air gap of PV panel, heat sink configuration and number of TEMs were not examined. Xi et al. [7] reviewed the development and application of solar-assisted TE technologies and concluded that the combination of (Thermoelectric cooler) TEC and PV cell can be used for air-conditioning purposes with reduced energy consumption and greenhouse gas emission [7]. He et al. [8] investigated the impact of sunlight based on the TE warming and cooling framework installed in a room with the volume of 0.125 m3. The results of their research revealed that the minimum temperature of 17 °C, COP of 0.45, and thermal efficiency of approximately 12% were attained. This framework increased the water temperature of a tank with the volume of 18.5 L by 9 °C. He et al. [9] researched a photovoltaic/thermal heat pipe panel that supports the heating and cooling system of TE system. The results demonstrated that the mean of COP, thermal efficiency, and electrical efficiency of this system can reach 1.7, 23.5%, and 16.7%, respectively. Furthermore, they demonstrated that the exergetic and energetic effectiveness of this system have inverse patterns. The exergetic effectiveness of this system in the winter operation mode is greater than that in the summer operation mode, whereas its energetic effectiveness is vice versa. However, if above studies [7-9] consider parameters such as subjective and objective comfort analysis, life cycle cost analysis of system and orientation of PV panels, and then the outcome will be more pronounced in term of economic and comfort effectiveness. Alomair et al. [10] performed an experiment to investigate the application of a solar-operated air conditioner in rural areas. There is a strong correlation between the size of TEMs and the cooling capacity of a solar-operated air conditioner. With the given air temperature, the power requirement of a system is directly proportional to the temperature difference between the cold and hot sides whereas COP is inversely proportional. Furthermore, other researchers [11] suggested a system installed with a hot water supply. The results indicated that this system is significantly affected by the water temperature. The COP of solar thermoelectric air conditioner with hot water supply (STACHWS) in water-heating and space-cooling mode decreases with the increase in water temperature. Surprisingly, the COP in water warming mode and space cooling 6

was as high as approximately 4.51. Finally, it can be concluded that the performance of the STACHWS system can be further enhanced by improving the input voltage, resistance of heat transfer, and dimensionless figure of merit ZT value. Liu et al. [12] again tested the ASTRW system in the winter operation modes. The result showed that an average internal surface temperature (Tr) of the ASTRW system was depended on the solar irradiation intensity during daylight of sunny winter day. At solar radiation of almost 325 W/m2 and heating capacity of 111 W/m2, the COP and thermal efficiency of the ASTRW system can achieve up to 2.3 and 34.2% respectively. While during the rainy winter's or cloudy day, Tr of the ASTRW system reaches to 15.7 °C with the maximum COP of about 2.0 and heating capacity of 36 W/m2 under the operating voltage of 2 V. Irshad et al. [13,14] examined the thermal load and comfort performance of an experimental chamber assisted with a (Photovoltaic wall) PV-W system in the south and a thermoelectric air duct (TE-AD) system in the north. The results revealed that the cooling behavior of this system increases when the power supplied to the TEMs by the PV system increased. The TE-AD system powered by PV panels was attained at 6 A where the cooling power of 517.24 W, COP of 1.15, and energy saving of 1806.75 kWh/year were achieved. Maria et al. [15] investigate cooling and heating performance of building envelope of volume 0.268 m3 by employing sixteen TEMs of RC12-8. Results show that when system was operated at 7.2-12 V COP of cooling ranges from 0.6 to 0.78 while cooling capacity ranges from 500-600W. Heating COP ranges in between 0.8-1.4 and heating capacity of system ranges from 500 to 1100 W. Atta [16] investigated the thermal performance of a closed space with the volume of 30 m3 using a solar-powered TE cooling system. The results showed that a temperature reduction of approximately 14 °C was attained when the framework was operated at 11.2 A and 12 V with the COP of 0.72. Liu et al. [17] developed a prototype of photo-thermoelectric ventilator (PVT-TEV) system consisting of thermoelectric ventilator, air flow channel and photovoltaic thermal system for Changsha China climate. Twelve thermoelectric modules were powered by 270 Wp PV panel was used for both heating of fresh air in winter and providing shading in summer season of Changsha. The result shows that average COP (heating) and thermal efficiency of PVT-TEV system was 6.4 and 26.7 %. However, this study didn’t considered parameters such as effect of air flow and economic comparison of PVT-TE with the existing systems. Daghigh and Khaledian [18] investigated the performance of solar thermoelectric cooling-heating system for Sanandaj, 7

Iran climatic condition. The system consisted of 100 Wp PV panel, four thermoelectric modules, battery, charge controller cooling chamber, hot water tank and compression cooling system. The results suggested that by using thermoelectric auxiliary system 725.8 kJ of energy was saved. It was suggested that further work by considering parameters such as flow analysis, cloudy season, economic analysis and comfort analysis will enhance the outcome of present work. Luo et al. [19] investigated building integrated photovoltaic thermoelectric (BIPVTE) wall system for six different cities of China. The results suggested that BIPVTE wall had ten times higher thermal performance than normal wall with additional benefit of 32.7 kWh/m2 power production and 30.91 kWh/m2 cooling energy. Thus the energy saving ratio of BIPVTE wall system as compared to normal wall system was 480%. Further work can be done by considering factors such as air gap between wall and PV panel, direction of PV panel, wall configuration, air flow and payback period. Amaia et al. [20] investigates the performance of ventilated active thermoelectric envelope module (VATE) in heating mode for Pamplona, Spain climatic condition. The results suggested that with the increase in input power from 66.8 to 273.6 W, COP (heating) decreases from 2.1 to 1.0. There were very few studies which accessed the Life Cycle Assessment (LCA) of a building installed with both the PV and TEMs systems. Bansal and Martin [21] compared the three local freezers: TE, vapor compression (VC), and absorption refrigeration (AR). The results showed that the overall operating and buying expenses over the lifetime of the systems were at the minimum level for the VC unit with US$ 351, followed by the TE, which cost nearly US$ 1381.2, and the AR, which cost US$ 1387.4. Riffat and Qiu [22] economically compared the three air conditioning systems: absorption air conditioner (AAC), TE air conditioners (TEAC), and vapor compression air conditioners (VCAC). For the total operation time of eleven years, the results showed that TEAC costs US$ 397 less as compared to VCAC and US$ 632 less as compared to AAC with the total electrical energy saving of 240 kWh and 336 kWh, respectively. Maneewan et al. [23] investigated the economic benefit of implementing TE air conditioning in a test room with the area of 16 m2. The results showed that the payback period and energy saving potential decrease as the number of TEM units increases, e.g., from 1 unit to 5 units. The maximum electrical saving (US$/year) was US$ 153.9 and the payback period of 0.75 year was achieved when the compact TE air conditioner consisted of 1-unit TEM. However, above three studies did not consider cost implication of PV panel integrated with TEMs system. Gillot et al. 8

[24] investigated the efficiency of the thermo-economic analysis of the TE cooling system powered by both PV and grid-connected systems. For two levels of input power i.e., 8 A (low level) and 4.8 A (high level), the results showed that the cooling energy cost ranged from US$ 0.55–0.68 for the case of high-level input, whereas it was US$ 0.55–0.78 for the low-level input when the interest rate fluctuated from 4% to 10%. Li et al. [25] economically analyzed the numerically developed PV-TE system, which comprises the PV, micro-channel heat pipe, TE, and heat sink. The results showed that the conventional PV-TE system incurs high cost even within the same area owing to the pair-arrangement between the PV and TE module. The cost was approximated as US$ 238, which was approximately 41 times higher than the additional cost of the new PV-TE. This suggested that the new PV-TE was more economically advantageous than the conventional PV-TE. Above two studies [24, 25] were conducted on small scale model with small testing time period. Luo et al. [26] developed the prototype of a building-integrated PV TE (BIPVTE) wall system. The performance of this system was compared with those of a normal massive wall and PV wall for the composite climate of China. Life-cycle assessment of the BIPVTE system using energy payback time was first conducted. The result showed that the BIPVTE system saves 102.6% more energy as compared to the massive wall in summer and 12% more in winter. The simulation results for composite climates of four cities of China showed that the BIPVTE system reduces the heating and cooling load by 110%–170%. Different studies have shown that the PV system installed either on the wall or on the roof of the building reduces thermal load with additional benefits of electrical energy production. On the other hand, the application of TEMs is limited for small scale cooling/heating or as insulation material due to low COP. There are limited researches focusing their application in providing economic benefits for full scale building application. Also, implementation of TEMs in an air duct for space conditioning of buildings has not been researched. Thus, this paper provides the in-depth analysis of carbon credit and life cycle of a PV_TE-AD cooling system under real building testing conditions of IPOH, Malaysia. First, the sizing methodology of PV and TE system components is presented. Second, the costs involved in the process of attaining, working, maintaining, and arranging the PV_TE-AD system are presented. Subsequently, the life-cycle assessment (LCA) and ecological benefits such as carbon credits of the PV_TE-AD system based on the reduction of CO2 emissions are determined. Subsequently, the results of LCA obtained from the three air conditioning systems i.e., normal split air conditioner, TE-AD 9

cooling system powered by a grid (G_TE-AD), and TE-AD cooling system powered by PV panels (PV_TE-AD) are presented and compared. 2. Methodology 2.1. Heat transfer model of TE and PV wall system a) Heat transfer on PV panel The energy balance equation of PV panel is defined as [27]:

 g cg

TP T T    (  g P )  ( g P )  b t x x z z

(1)

whereby, b=(Sc+SpTP)/  Heat transfer from glass panel with solar cell is given by [28] and defined as:

S c  [  (1   )]G  E  hcoTa  1hroTa  hci Te   2 hriTwo ]

(2)

S p  (hco  1hro  hci   2 hri )

(3)

Heat transfer from glass panel without solar cell is given as:

S c  [G(1   )  hcoTa  1hroTa  hciTe   2 hriTwo ]

(4)

S p  (hco  1hro  hci   2 hri )

(5)

PV glass panel surface radiant heat transfer coefficients are given as: hro   (TP2  Ta2 )(TP  Ta ),

(6)

2 hri   (TP2  Tcold )(TP  Tcold )

(7)

b) The air duct energy balance equation is given as : .

.

m C PTe  hci (T p  Te ) w.dX  m C P (Te  dTe )  hwo (Te  Twi ) w.dX  dT C P D.w.dX e dt

(8)

10

.

where, m is the mass flow rate of air and is given by ρwD.Va DC p 

dTe dT  hi (TP  Te )  hwo (Two  Te )  Va DC p e dt dx

(9)

The velocity of air flow in the air duct Va can be calculated as follow [28] 0.5 Xg (Tout  Tin ) L  (P /  ) C f (L / d )

Va 

Heat transfer model of Photo Voltaic Wall system  w (

Tw ) y0  hwo (Two  Te )  1hrwo (Two  Tp )  G wall NPV (1   ) Y

(10)

 w (

 Tw ) y Dw  hwi (Twi  Tin ) Y

(11)

Heat transfer model of Normal wall system:  w (

Tw ) y0  hnwo (Tnwo  Ta )  1hnrwo(Tnwo  Ta )  G nwall Y

(12)  w (

 T ) y Dw  hnwi (Tnwi  Tin ) Y

(13)

The TE-AD assisted test room heat transfer energy balance equation is given as [28] .

.

m C PTr  [hnwi (Tnwi  Tin )  hte Ate (Te  Tcold )].wroom.dX  m CP (Tin  dTin )  dT CP Lroom.wroomdX in dt

(14)

Heat transfer model for TEMs is govern by four type of heat used to defined cooling and heating capacity TEMs i.e. Peltier cooling (QPEC), Peltier heating (QPEH), Joule heat(QJH), and Fourier heat (QFH), given as [29]:

QPEC  ITcold

(15)

11

QPEH  IThot

(16)

QJH  I 2 R

(17)

QFH  K (T hotTcold ) (

(18)

By using Eqs. 15-18, TEMs cooling and heating capacity was defined as [30]

Qcold  STE ITcold  0.5I 2 RTE  K TE T

(19)

STE  2 N

(20)

RTE  2 N / G ’

(21)

K TE  2 NG '

(22)

Qhot  STE IThot  0.5I 2 RTE  KTE T

(23)

Vin  (STE  (Thot  Tcold ))  ( I  RTE )

(24)

Energy balance equations of hot and cold side can be given as [31]: hTE ATE (Ta  Tcold )  ITC  0.5I 2 R  K (Thot  Tcold )

(25)

hTE ATE (Thot  Ta )  ITh  0.5I 2 R  K (Thot  Tcold )

(26)

The input power to the TEM was given by [31]:

PTE  I (Thot  Tcold )  I 2 RTE

(27)

2

Z

STE RTE KTE

(28)

COP of thermoelectric module in cooling mode is given by [32] COPTEcooling 

Qcold PTE

(29)

The COP of system in cooling mode was given by: 12

Qcold ( PTE  W )

COPTE  ADsystem 

(30)

For TE-AD system, cooling capacity QTE-AD was evaluated by using the following equations: .

QTE  AD  C p ,air m(Ta  Tout )

COPTE  AD 

QTE  AD nPTE

(31)

(32)

2.2. Sizing methodology of TE and PV system components Appropriate PV modules and TEMs were chosen to provide the as-needed cooling capacity with the objective of delivering adequate cooling with the incorporation of TE-AD and PV systems. The specifications of the measuring equipment, PV panel and TEMs are listed in Table 1, 2 and 3. Before the installation of the TE air duct and PV module, the highest cooling load of the test room could reach approximately 370 W. As mentioned in the previous study [33], each TEM produces low refrigeration efficiency. The TE-AD system can function at the optimum level at 5 V and 6 A. Therefore, 15 units of TEMs were required to achieve the cooling load of 370 W or generate the cooling power of 375 W, which consumes 450 W of energy. Figures 1 and 2 shows that the surrounding air was distributed internally after installing a fan using the TE-AD system set up in a room located in the north. Furthermore, installing a PV panel (south side) can help produce electrical energy, but also decreases the heat gain of the wall. The as-produced energy was directly utilized by this system using a current controller as the PV panel can produce current for only 5–6 h per day with an approximate panel efficiency of 70%–80%. A maximum power of 80 W can be generated by a 100-W (Wp) solar panel for 6 h. This results in the energy of 5 h × 100 × 0.7 = 420 Wh, where 0.7 is the minimum power loss in the system. This energy generated was accumulated in the battery of size 12 V, 125 Ah via a charge controller. Referring to the calculation stated above, the TE-AD system required 450 W per hour for its optimum operation. Therefore, three 100 Wp solar panels and three 12-V, 125-Ah batteries were used to generate the energy of 1050 Wh and store the energy of 3600 Wh. In order to prevent power disruptions, an alternative power source was connected to the system. Under these 13

circumstances, DC current produced a difference in temperature between the hot and cold parts of the TEMs unit. Hot side of TEMs consisted of heat sinks for proper dissipation of heat via forced convention through fan.

Figure 1: Test room with the thermoelectric air cooling system on the north wall and PV panel on the south wall

14

Figure 2: Schematic line diagram of test room with PV wall and TE-AD system Table 1: Specification of measuring equipment Apparatus Thermoelectric modules (TEMs)

Type Heibei TEC1-12730

Quantity 24

Function To create a temperature gradient from an applied electric current

DC Power Supply

CPX400DP

1

To supply current into TEMs

Specification Maximum Current Input = 30.5A@15V Qmax=257W @Th=25°C Qmax=282W @Th=50°C Dual output, each with: 420W, Vmax=60V, Imax=20A. Voltage and current draw can be adjusted.

15

Heat sinks

Finned Aluminum

Hot wire Anemometer

Thermocouple

24

1

Type-K

To improve heat dissipation on hot side of TEM To measure air speed for controlling fan speed

10

To measure temperature

Globe thermometer

1

To measure mean radiant temperature

Advanced Solar Power Meter

1

To measure solar irradiation

Fan

HDEF-12 Exhaust Fan

2

Data logger

midi Logger GL220

1

Solar Battery

3

For air speed: ± (5% + 0.1 m/sec), ± (5% + 0.3 km/hr), ± (5% + 0.2 mph), ± (5% + 0.2 knots), ± (5% + 20 ft/min); for temperature: ± 1.5 o F (± 0.8 ºC) Kept at 0 ˚C, measured accuracy within ±0.1 ˚C Diameter= 150mm Range= -50 to 300 ˚C with accuracy of ±0.1 ˚C Resolution:1W/m 2

Spectral response: 400-1100nm Accuracy ± 2W/m2 To assist TE-AD by 230V, 56W controlling air flow 9” Diameter into the duct Speed = 1400rpm Max air flow = 10-15m3/min To record measured Every 10-min data intervals record To store electrical energy produce by PV panel

Table 2: Specifications of the PV system Mechanical Specification Characteristic

Details 16

Cell size Module dimension (L × W × T) Number of cells Weight Cable length

156 mm × 104 mm 1205 mm × 655 mm × 34 mm 4 × 9=36 8.9 kg 900 mm for positive (+) and negative (−) MC-IV IP65 Rated 4 installation holes

Type of connector Junction box Number of holes in frame Electrical specifications (STC*=25 °C, 1000 W/m2 Irradiance and AM=1.5) Characteristic Details Maximum system voltage 600 V Maximum peak power, Pmax 100 W (0%, +6%) Maximum power point voltage, Vmpp 18.0 V Maximum power point current, Impp 5.56 A Open circuit voltage, Voc 21.9 V Short circuit current, Isc 6.13 A Module efficiency (%) 14.63 % Temperature coefficient of Voc (−0.32% /°C) Temperature coefficient of Isc (0.04% /°C) Temperature coefficient of Pmax (−0.45% /°C) Other Performance data Power tolerance Operating Maximum NOCT* temperature series fuse rating −5%, +10% −40° C to +85 °C 10 A 46 °C ± 2 * Normal operating cell temperature

Table 3: Thermoelectric module properties Type

Dimensio

N

Imax(A)

n(mm) TEC

62 × 62 × 127

1-

4.8

30

Tmax( RTE(  )

STE

KTE

(W)

°C)

(V/K)

(W/°C)

266.7

68

0.051

0.5177

Umax(V) Qcmax

15.4

0.27

12730 Table 4 presents a comparison of the specifications of the two air conditioning systems used to reduce the thermal load of the test rooms with similar dimensions. The capacity of the air conditioners was chosen based on the ASHRAE Standard 62.2 [34]. The energy consumed by 17

these systems and the room temperature were noted after 8 h of operation every day. The energy utilization of the TE-AD system (operated at 6 A) was recorded and the set-point temperature of the split air conditioner was maintained at 24 °C. For almost all the offices in Malaysia, the setpoint temperature is within the range of 24–26 °C [35]. Low COP of TE-AD cooling system is due to the merit of ZT =S2T/ of TEM of TEC1-12730 is less than 1, and number of thermocouples is 127. Thermoelement length, thermoelement length to cross-sectional area ratio, slenderness ratio is also low for TEC1-12730. Reliability issue of the metallized contact layer is another reason of low COP. It has been identified that direct connecting the TEMs was leading to the occurrence of a reaction, poor wettability of solder and diffusion to occur between the materials. Further, the thermal design of the heat sinks geometry, allocation of the heat transfer area and heat transfer coefficients of hot and cold side of the heat sinks, thermal and electrical contact resistances and interface layer analysis also causes reduction in COP of system. Table 4: Specifications of the TE-AD and split air conditioner systems Category Refrigeration

Sound (indoor/outdoor), Db Dimension (mm3)

Heaviness (indoor/outdoor), (kg) Lifespan, years Equipment cost, US$

Normal air conditioner 2450–3100

Thermoelectric air cooling system 330–670

Electrical consumption, W

850–970

550–700

COPc Range of working temperature, °C

2.2–3.0 16–42

0.5–0.9 24–38

37/52

23

870 × 195 × 290 (Indoor) 840 × 540 × 300 (Outdoor) 8.8/30.2

660 × 330 × 1400

Approximately 15

Approximately 25

275–315

700–1000

Cooling Power, W

9

The electrical consumption of the test room contained three load components and each load is listed in Table 5. 18

Table 5: Load requirements of the TE-AD system S.No.

Appliance

1

Thermoelectric module

15

Cold-side Exhaust fan Hot-side Exhaust fan

1

I(A) 2 3 4 5 6 7 30

1

56

2 3

Number

Power (W)

rating Utilization (h/day) V 5 5 5 5 5 5

P(W) 10 15 20 25 30 35

Utilization per day (Wh/day)

8

8

80 120 160 200 240 280 240

8

448

As this system was operated with constant current, the electrical load on the south-facing PV wall remained constant. The area available for the installation of the PV panel on the wall was limited and only three panels of 100 Wp could be accommodated. Consequently, the output power produced by the PV system was not sufficient to operate the TE-AD system for the entire day. Therefore, a DC power source was installed together with the PV system as a power backup in case of power shortage. The duration of daylight in Malaysia fluctuates from 5 to 6 h every day. The test room is located in Ipoh, Perak, Malaysia where the normal number of daylight hours per day was experimentally calculated as 5.5 h. The data of solar radiation and surrounding temperature for four cloudless days (12nd-16th May 2017) were shown in Figure 3.This system was tested for one complete year and data can be obtained from previous work [13]. The experiment were carried out under cloudless, cloudy and rainy climatic conditions. Fifteen KType thermocouples were used to measure temperature and data were recorded by using data logger (GL840-M 20 Channel Midi Data Logger) as shown in Figure 3.

19

40

900 T_a(°C)

Solar Radiation(W/m2) 800

35

Temperature (ºC)

600

25

500 20 400 15

300

10

Solar Radiation (W/m2)

700

30

200

5

100

0

0 6

16

26

36

46

56

66

76

86

96

Time (hr)

Figure 3: Four-day variation of solar radiation and ambient temperature with time The uncertainty analysis of parameter measured such as temperature, solar radiation and humidity was done as bias errors. This analysis was performed outside and just a constrained measure of time was accessible to take measurements. Along these lines, it was impractical to get a similar climate conditions several times and repeat the estimations of the parameters to assess the precision error. Subsequently, only the bias error was considered in the estimation of the uncertainty as presented in Table 6. The uncertainties of every measured variable were assessed with 95% confidence and consider as the safest estimation of the uncertainty. Table 6. Uncertainty analysis of measured value Variable

Typical value(x)

Uncertainty( x )

Relative uncertainty (

T_In(°C) T_a(°C)

16-35 20-40

0.1 0.1

x )% x

0.56 0.55 20

T_C(°C) T_H(°C) Solarimeter (W/m2) Voltage (V) Current (A)

15-25 25-40 100-900 0-30 0-10

0.1 0.1 2

0.67 0.4 2 0.3 1

3. Cost estimation of TE air cooling and PV wall system There are several costs involved in acquiring, working, maintaining, and arranging a system. For the existing system, the LCA was analyzed by assuming the useful life of both the PV and TEAD systems as 25 years and that of the battery bank as 5 years. This investigation was done to assess the general expense of making choices and choosing a configuration that guarantees the lowest general expense with high quality and capacity over a given life period. The line cash flow diagram of the south-facing PV wall system for various time intervals is shown in Figure 4. The cash outflow or expense is represented by vertically downward line arrow and revenue or cash inflow is represented by vertically upward line arrow and number on the flow line represent years. Pi is the initially investment in setting the system while (M) represent maintenance cost incurred every year while running system. The salvage cost (S) is the revenue generated while scraping out the system.

Figure 4: Line cash flow diagram of PV panel.

21

3.1. Initial cost of south-facing PV module The cost of the PV module can be obtained by using Eq. 33 as follows [36]: CPV = NPV

Wp(PV)

C/Wp .

(33)

The price of the PV module supplied by the manufacturer was US$ 4.4/Wp. The cost of the battery bank can be obtained as follows: CBattery = Ah

Nbattery

C/Ah .

(34)

The price of the battery bank as supplied by the manufacturer was US$ 1.2/Ah. The cost of the charge controller can be calculated using the following equation: Ccharge controller= Acharge controller

C/A.

(35)

The price of the charge controller supplied by the manufacturer was US$ 6.1. The capital cost of the PV system (Pi) without including the cost of the land can be estimated as follows: Pi = Carray + Cbatterybank +Ccharge controller .

(36)

The average annual cost of repair and maintenance of the south-facing PV system is denoted as M. Its value in terms of the present value is given by [36]

PRM

 (i  1) n  1  M  n   i (i  1) 

(37)

During the operation of the PV system, the batteries should be replaced every five years. Therefore, the net replacement cost incurred after every five years in terms of the present value is given by C  C  C  C  C  PRe place   Battery5    Battery10    Battery15    Battery20    Battery25   (1  i)   (1  i )   (1  i)   (1  i )   (1  i) 

.

(38)

22

Eventually, the system should be demolished and disposed, and the cost incurred during this operation is referred to as the salvage cost, which is defined as:

 1  PS  S   n  (i  1) 

(39)

Thus, the overall LCA analysis of the south-facing PV system is given by [36] LCA = Pi + PRM + PReplace - PS

.

(40)

The capital recovery factor over the lifetime of the PV system can be obtained using the relation proposed by Raman and Tiwari as follows [37]:  i (i  1) n  FCR    n  (i  1)  1 .

(41)

The equations above can be utilized to calculate the annual cost of the south-facing PV system CUAcost over a lifetime of 25 years as follows: CUAcost= LCA

FCR .

(42)

The aggregation of yearly unit of electrical energy consumption (E) by a specified electrical load is resolved as follows: E(kWh/year) = E(kWh/day)

n /year

(43)

The electrical energy produced by the PV system, E PV, can be calculated as follows:

1.1  CUA cos t  E PV (US $ / kWh)    E  

(44)

3.2 LCA analysis of the TE-AD system The economic analysis of this system (TE-AD) in comparison with the traditional system was conducted after considering an interior set-point for energy saving [38]. For the purpose of 23

comparison, the other test room was installed with a split-type air conditioner (0.75-ton capacity). It had similar specifications and dimensions as this system. The energy utilization and room temperature of the air conditioner and TE-AD system were observed after 8 h of operation each day. The set-point temperature varied between 24–28°C whereas the surrounding temperature varied between 24 °C and 34 °C. The highest day-to-day energy utilization of the air conditioner was observed to be 10.23 kWh (24 °C), whereas the lowest day-to-day energy utilization of the air conditioner was observed to be 6.53 kWh (28 °C). Hence, the decrease in the mean of energy utilization was equal to a unit increase in set-point temperature (9.04%). For most offices in Malaysia, the set-point temperature of the room was between 24 °C and 26 °C. The difference in the time period of LCA calculation and actual experimental operation was solved on TRNSYS simulation software. Detailed TRNSYS modeling were explained in previous study [13, 33]. Some assumptions were made in the case of the TE-AD system to ease the comparison by estimating the prices as described below: 

The lifespans of this system and the air conditioner are 25 years based on the estimation by the manufacturer.



According to Bank Negara Malaysia, the inflation rate of Malaysia is approximately 3.72% and the interest rate is approximately 3.15% [39].

In order to estimate the depreciation value of this system, the diminishing value (DV) method was employed as it can help estimate the diminishing value over the entire accounting life of the system effectively. The annual DV for both the systems was computed by using: Vn =Ci

(1-DV factor)n

(45)

The DV factor was chosen to be 15%, 10%, and 7.5% with respect to the life expectancy of an air-conditioner. The operating prices excluded the price of maintenance and only the power utilization was considered. Cannual = E (kWh/year)

Pe

(46)

A payback period was used to obtain the time required for the funds of electricity savings, which could be attributed to the application of this system. It refers to the time needed by this 24

framework to offset the assets used as investment and can be computed according to the following formula [40]:

C  B[

(1  i ) n  1 ] i (1  i ) n

(47)

By determining the actual cost of TEMs, the total cost of TEMs can be obtained by using the following equation: CTEM= N

C/TEMs

(48)

The cost of TEMs supplied by the manufacturer was US$ 28.3/TEM [41]. By determining the actual air flow rate required in the experiment, the cost and power of the fan required can be obtained as follows: CFan = Nfan

C/fan

(49)

The cost of the fan provided by the manufacturer was US$ 31.6. The cost of aluminum casing can be obtained by using the following equation: CAl = dAl (inch)

C/inch

(50)

The price of aluminum sheets supplied by the manufacturer was US$ 12.6/m2. The cost of insulation sheet can be obtained by using the following equation: Cins = dins (inch)

C/inch

(51)

The price of insulation sheet supplied by the manufacturer was US$ 4.2/m2. The cost of aluminum heat sink can be obtained by using the following equation: CHS = NHS

C/HS

(52)

The price of heat sink supplied by the manufacturer was US$ 2.3/piece [42].

25

The capital cost of the TE-AD system (Pi) excluding the cost of land can be estimated as follows: PiTEAD = CTEMs + CFan + CMis

(53)

Other costs such as replacement, maintenance, and salvage costs of the TE-AD system were considered to be negligible. The capital cost of the PV and TE-AD system (Pi) excluding the cost of land can be estimated as follows: Pi PV-TEAD= Carray + Cbatterybank + Ccharge controller + CTEMs + CFan +CMis

(54)

As there were no replacement, repair, and salvage costs of the TE-AD system, these costs associated with the south-facing PV wall system were thus added in the case of this combined system. Therefore, the overall LCA analysis of these systems in terms of the present value was calculated as: LCA = Pi + PRM + PReplace - PS

(55)

3.3 Mitigation of CO2 emissions and carbon credit potential In Malaysia, buildings are equipped with air cooling system to offer thermal ease to the residents and this has certainly resulted in increased consumption of fossil fuel resources. The total number of CO2 emissions in Malaysia has surged to 221% from the years 1990 to 2004 and it is estimated to increase drastically up to 328 million tons by the year 2020 [43]. Therefore, the TEAD system and TE-AD equipped with PV system have become dependable, and green technologies are vital in mitigating the emission of CO2. Numerical calculations were performed to calculate the volume of reduction of CO2 emission owing to the present TE-AD and combined systems (PV and TE-AD) when compared to the traditional systems. The mean intensity of CO2 discharged from a thermal power plant operated using coal in Malaysia was 1.21 kg/kWh [44]. In order to calculate the total reduction of CO2 emissions from the current TE-AD, combined (TE-AD and PV), and traditional systems for a lifetime of 25 years, Eq. (56) [45] was used as follows:

26

CO2 (kg/life) = 1.21(kg/kWh)

E (kWh/year)

n (year)

(56)

Carbon dioxide emission during manufacturing phase of photovoltaic assisted TE-AD system was not considered in the LCA calculation due to unavailability of data. With regard to the aggregated sum of reduction of CO2 emission, the carbon credit potentials of the TE-AD and combined PV and TE-AD systems were distinguished. In order to calculate the amount of carbon credit achieved by the system, Eq. (57) [36] was used as follows: Cc= US$13/ton

CO2 (tons/life)

(57)

From Eq. (57), US$ 13/ton of CO2 emission represents the value estimation of one carbon credit for the reduction of 1 ton of CO2 emission [46]. The carbon credit obtained using a non-polluting PV system affects the electrical expenses. By considering the effect of carbon credit obtained, Eq. (55) was modified as follows: LCA = Pi + PRM + PReplace - PS – Cc

(58)

4. Results and discussion 4.1 Test room installed with grid-connected TE-AD system For the existing TE-AD system, the LCA analysis was conducted and it is presented in Table 7. The LCA analysis showed that the total cost of the TE-AD system over its lifetime was determined to be US$ 642.0 with zero repair or maintenance and salvage costs as listed in Table 7. Table 7: LCA analysis of the TE air duct system S No. 1 2 3 4 5 5

Component TE Module Fan Aluminum casing Insulation sheet Heat sink Initial TE-AD system cost (Pi)

Quantity 15 2

Cost per unit (US$) 31.60 28.30

15

2.30

Cost (US$) 474.00 56.60 46.00 31.00 34.50 642.00

27

6 7 8

Repair and maintenance cost (PRM) Salvage cost (Ps) LCA

642.00

4.2 Test room installed with PV-assisted TE-AD system The LCA analysis of the G_TE-AD system described in the previous section indicated that the TE-AD system is a decent other option to the traditional air conditioning system owing to its reduced energy consumption and lesser dependence on fossil resources. The energy requirement of this system was reduced by providing two power sources, i.e., grid power supply and PV panel power supply. The size and LCA analysis of the south-facing PV system are presented in Table 8. The LCA analysis of the PV panel suggested that the total LCA value of the PV system reached up to US$ 2299.00 after adding the repair, replacement, and salvage costs. Furthermore, the addition of the PV panel to the TE-AD framework increased the initial investment cost. The LCA analysis of the PV_TE-AD system is presented in Table 9, which suggests that the present system has higher LCA than the G_TE-AD system. Table 8: Sizing and LCA analysis of PV system S No. 1 2 3 4 5 6 7 8

Parts Photovoltaic panel Battery bank Charge controller Cost of initial south-facing PV wall (Pi) Repair and maintenance cost (PRM) Replacement cost (Preplace) Salvage cost (Ps) LCA

Capacity

Price per unit

Price (US$)

300 Wp 475 Ah 20 A

4.40 US$/Wp 1.20 US$/Ah 6.10 US$/A

1320.00 570.00 122.00 2012.00 201.72 138.60 53.00 2299.00

The LCA analysis of the PV_TE-AD framework as shown in Table 9, depends upon the energy harness efficiency of PV panel mounted on the wall. Variation of solar power output with solar irradiance is shown in Figure 5. Results demonstrates that the power output from the south wall facing PV panel increases when falling solar irradiation rises and achieves a maximum up to 28

166.7 W at 13:00 hr. South facing PV wall panel generates elevated electrical energy during the time period of 11:00 hrs to 16:00 hrs. PV panel of capacity 300 Wp can produce 1.2 kWh of energy per day and 29.8 kWh of energy per month.

Figure 5: Variation of solar radiation and power production of south mounted photovoltaic wall (6th May 2017) Combination of PV system with TE-AD cooling system increases initial capital cost of overall system due to additional cost incurred by PV system. However, the operating cost of the system was reduced as presented in Table 9. Table 9: LCA analysis of the test room installed with TE and PV air duct systems S No. 1

Parts Photovoltaic panel

Capacity 300 Wp

Price (US$) per unit 4.40 /Wp

Price (US$) 1320.00

29

2

Battery bank

3

Charge controller

4

TE Module

5

Fan

6

Aluminum casing

7 8 9

Insulation sheet Heat sink Cost of initial southfacing PV wall and TE-AD system (Pi) Repair and maintenance cost (PRM) Replacement cost (Preplace)

10 11

12

Salvage cost (Ps)

13

LCA

475 Ah

1.20 /Ah

570.00

20 A

6.10 /A

122.00

15

31.60

474.00

2

28.30

56.60 46.00

15

31.00 34.50 2654.10

2.30

201.72 138.60

53.00 2941.42

Table 10 presents the differences among the electrical energy savings of the PV_TE-AD, G_TEAD, and split air conditioner (capacity 0.75 ton) systems. After 8 h of operation each day, the room temperature and energy consumed by these systems were recorded. The energy consumption of G_TE-AD and PV_TE-AD systems (operated at 6 A) were recorded and the setpoint temperature of the split air conditioner was maintained at 24 °C. Table 10: Comparative analysis of the three modes of systems Comparative systems

Electrical energy consumption (kWh/year) Saving in term of Electrical Energy (kWh/year)

Types of air cooling system Normal air Grid-connected TEconditioner AD (15 TEMs) system 2650.00 1560.00 0

1090.00

TE-AD system powered by PV panel 820.00 1830.00

30

Running price (US$/year) Running price saving (US$/year) CO2 reduction (ton/life) Payback period (years)

197.00

90.00

0

107.00

46.0 151.00

0

35.49

60.24

NA

4.2

4.8

The result shows that 1090.0 kWh/year of energy can be saved when the G_TE-AD system is operated in the optimal mode (5 V and 6 A). The integration of a PV system with the TE-AD system has further enhanced the reduction in energy consumption. In comparison with the split air conditioner (0.75 ton), this combined system saves 1830.0 kWh/year as presented in Table 10 and Figure 6. 250 2650 2500

197

Electrical energy consumption (kWh/year) Operation cost (US$/year)

200

2000 150

1560 1500 90 1000

100 820 46

500 0

Cost (US$/year)

Electrical Energy consumption (kWh/Year)

3000

50

0 Split Air condition

Grid connected TE-AD

PV assisted TE-AD

Type of air conditioner

Figure 6: Energy and operation cost variation of different types of air conditioners Furthermore, it was observed that 69.05 % more energy can be saved by utilizing the PV_TEAD system as compared to the G_TE-AD system. The operational costs of the PV_TE-AD system were US$ 151.0 and US$ 44.0 lower than those of split air conditioner (0.75 ton) and G_TE-AD systems, respectively, with a payback period of 4.8 years, which is shorter than those 31

of the latter systems. The comparison of the total amount of CO2 emissions demonstrates that the G_TE-AD system achieves a reduction of 35.49 tons of CO2 emissions in its lifetime. The reduction of CO2 emission was further improved by integrating a solar panel with the TE-AD system. The reduction of CO2 emission of the PV_TE-AD system reaches up to 60.24 tons when compared to the 0.75-ton air conditioner. Limitation of present study includes the performance of TEMs, which is greatly depended on the merit of ZT =S2T/. Nevertheless, a high peak ZT within a limited temperature range is not adequate due to low efficiency. It has been identified that direct connecting the TEMs was leads to the occurrence of a reaction, poor wettability of solder and diffusion to occur between the materials. Further analysis of parameters such as CO x, NOx, SOx, etc. can be included by considering manufacturing phase in life cycle analysis. 5. Conclusions This study investigated a novel TE-AD system for cooling buildings in tropical climate. The efficiency of the TE-AD system was evaluated by incorporating PV into the TE-AD system. The performance of this system was analyzed by evaluating parameters such as energy consumption, cost benefits, and reduction of CO2 emission. The following conclusions can be drawn. 

After comparing the LCA analysis of the three air conditioning systems, it was observed that the PV_TE-AD system had lower energy consumption and carbon emission with higher economic benefits as compared to the other cooling systems.



The PV_TE-AD system incurred energy expenses up to 1830.0 kWh/year and 740.0 kWh/year lower than the corresponding values of the split air conditioner (0.75 ton) and G_TE-AD system, respectively.



The PV_TE-AD system had an operational cost US$ 151.0 and US$ 44.0 lower than those of the split air conditioner with 0.75-ton capacity and G_TE-AD system, respectively.



The split air conditioner and G_TE-AD system produced 60.24 tons/life and 35.49 tons/life more CO2 emission when compared to the PV_TE-AD system.

32



The PV_TE-AD system had a payback period of 4.8 years whereas that of the G_TE-AD was 4.2 years. Owing to its higher initial investment cost, the payback period of PV_TE-AD system was longer. Nevertheless, the lower operational cost of the PV_TE-AD system provides long-term economic benefits to the end user.

Although the TE-AD system has lower COP than the traditional system, it can be implemented in a less fluctuating environment for space conditioning. TE-AD can be attached to other components, such as an air distribution system, which can aid in reducing the losses occurring in the air-duct system and improve the cooling performance. The integration of PV system with the TE-AD system increases the thermal comfort and COP of the system while reducing the CO2 emission, energy consumption, and thermal load of the test room. Thus, the novel TE-AD system assisted by a PV system achieves a Freon-free solution with less fossil fuel dependency, less energy consumption, and less CO2 emission for space conditioning. Acknowledgements The authors would like to acknowledge the Deanship of Scientific Research for proving administrative and financial supports. Funding for this work has been provided by the Deanship of Scientific Research, King Khalid University, Ministry of Education, Kingdom of Saudi Arabia under research grant award number (R.G.P.1/62/40). The authors also would like to thank Universiti Teknologi PETRONAS (UTP), Malaysia for providing support in performing experiments. References 1. D.B. Jani, M. Mishra, P.K. Sahoo, Performance studies of hybrid solid desiccant-vapor compression air-conditioning system for hot and humid climates, Energy Build. 102 (2015) 284–292. 2. Air

conditioning

rise

raises

temperature,

Climate

News

Network.

(2015).

http://climatenewsnetwork.net/air-conditioning-rise-raises-temperature/ (accessed April 3, 2018) 33

3. Z. Liu, A. Li, Q. Wang, Y. Chi, L. Zhang, Performance study of a quasi grid-connected photovoltaic powered DC air conditioner in a hot summer zone, Appl. Therm. Eng. 121 (2017) 1102–1110. 4. X. Zhang, M. Li, Y. Ge, G. Li, Techno-economic feasibility analysis of solar photovoltaic power generation for buildings, Appl. Therm. Eng. 108 (2016) 1362–1371. 5. M. Sajid, I. Hassan, A. Rahman, An overview of cooling of thermoelectric devices, Renew. Sustain. Energy Rev. 78 (2017) 15–22. 6. A. Abdul-Wahab, A. Elkamel, A.M. Al-Damkhi, I.A. Al-Habsi, H.S. Al-Rubai’ey’, A.K. AlBattashi, A.R. Al-Tamimi, K.H. Al-Mamari, M.U. Chutani, Design and experimental investigation of portable solar thermoelectric refrigerator, Renew. Energy. 34 (2009) 30–34. 7. H. Xi, L. Luo, G. Fraisse, Development and applications of solar-based thermoelectric technologies, Renew. Sustain. Energy Rev. 11 (2007) 923–936. 8. W. He, J. Zhou, J. Hou, C. Chen, J. Ji, Theoretical and experimental investigation on a thermoelectric cooling and heating system driven by solar, Appl. Energy. 107 (2013) 89–97. 9. W. He, J. Zhou, C. Chen, J. Ji, Experimental study and performance analysis of a thermoelectric cooling and heating system driven by a photovoltaic/thermal system in summer and winter operation modes, Energy Convers. Manag. 84 (2014) 41–49. 10. M. Alomair, Y. Alomair, S. Mahmud, H. a. Abdullah, Theoretical and Experimental Investigations of Solar-Thermoelectric Air-Conditioning System for Remote Applications, J. Therm. Sci. Eng. Appl. 7 (2015) 21013. 11. Z.B. Liu, L. Zhang, G. Gong, Y. Luo, F. Meng, Experimental study and performance analysis of a solar thermoelectric air conditioner with hot water supply, Energy Build. 86 (2015) 619–625. 12. Z. Liu, L. Zhang, G. Gong, Y. Luo, F. Meng, Evaluation of a prototype active solar thermoelectric radiant wall system in winter conditions, Appl. Therm. Eng. 89 (2015) 36–43.

34

13. K. Irshad, K. Habib, F. Basrawi, B.B. Saha, Study of a thermoelectric air duct system assisted by photovoltaic wall for space cooling in tropical climate, Energy. 119 (2017)504522. 14. K. Irshad, K. Habib, M.W. Kareem, F. Basrawi, B.B. Saha, Evaluation of thermal comfort in a test room equipped with a photovoltaic assisted thermo-electric air duct cooling system, Int. J. Hydrogen Energy. 42(2017) 26956-26972. 15. M. Ibañez-Puy, J. Bermejo-Busto, C. Martín-Gómez, M. Vidaurre-Arbizu, J.A. SacristánFernández, Thermoelectric cooling heating unit performance under real conditions, Appl. Energy. 200 (2017) 303–314. 16. R.M. Atta, Solar thermoelectric cooling using closed loop heat exchangers with macro channels, Heat Mass Transf. 53(2017) 2241–2254. 17. Z. Liu, Y. Zhang, L. Zhang, Y. Luo, Z. Wu, J. Wu, Y. Yin, G. Hou, Modeling and simulation of a photovoltaic thermal-compound thermoelectric ventilator system, Appl. Energy. 228 (2018) 1887–1900. 18. R. Daghigh, Y. Khaledian, Effective design, theoretical and experimental assessment of a solar thermoelectric cooling-heating system, Sol. Energy. 162 (2018) 561–572. 19. Y. Luo, L. Zhang, Z. Liu, J. Wu, Y. Zhang, Z. Wu, Numerical evaluation on energy saving potential of a solar photovoltaic thermoelectric radiant wall system in cooling dominant climates, Energy. 142 (2018) 384–399. 20. Z.-R. Amaia, M.-G. César, I.-P. Elia, V.A. Marina, I.-P. María, Design, assembly and energy performance of a Ventilated Active Thermoelectric Envelope module for heating, Energy Build. 176(2018)371-79. 21. P. Bansal, A. Martin, Comparative study of vapour compression, thermoelectric and absorption refrigerators, Fuel Energy Abstr. 41 (2000) 320. 22. S.B. Riffat, G. Qiu, Comparative investigation of thermoelectric air-conditioners versus vapour compression and absorption air-conditioners, 24 (2004) 1979–1993. 35

23. S. Maneewan, W. Tipsaenprom, C. Lertsatitthanakorn, Thermal comfort study of a compact thermoelectric air conditioner, J. Electron. Mater. 39 (2010) 1659–1664. 24. M. Gillott, L. Jiang, S. Riffat, An investigation of thermoelectric cooling devices for smallscale space conditioning applications in buildings, Int. J. Energy Res. 34 (2010) 776–786. 25. G. Li, X. Zhao, J. Ji, Conceptual development of a novel photovoltaic-thermoelectric system and preliminary economic analysis, Energy Convers. Manag. 126 (2016) 935–943. 26. Y. Luo, L. Zhang, Z. Liu, J. Wu, Y. Zhang, Z. Wu, X. He, Performance analysis of a selfadaptive building integrated photovoltaic thermoelectric wall system in hot summer and cold winter zone of China, Energy. 140 (2017) 584–600. 27. K. Vats, G.N. Tiwari, Performance evaluation of a building integrated semitransparent photovoltaic thermal system for roof and fac, Energy Build. 45 (2012) 211–218. 28. J. Jie, Y. Hua, P. Gang, J. Bin, H. Wei, Study of PV-Trombe wall assisted with DC fan, Build. Environ. 42 (2007) 3529–3539. 29. D. Enescu, E.O. Virjoghe, A review on thermoelectric cooling parameters and performance, Renew. Sustain. Energy Rev. 38 (2014) 903–916. 30. W. He, J. Zhou, J. Hou, C. Chen, J. Ji, Theoretical and experimental investigation on a thermoelectric cooling and heating system driven by solar, Appl. Energy. 107 (2013) 89–97. 31. H.J. Goldsmid, Introduction to Thermoelectricity, 2010. 32. G. Tan, D. Zhao, Study of a thermoelectric space cooling system integrated with phase change material, Appl. Therm. Eng. 86 (2015) 187–198. 33. K. Irshad, K. Habib, N. Thirumalaiswamy, B.B. Saha, Performance analysis of a thermoelectric air duct system for energy-efficient buildings, Energy. 91 (2015) 1009–1017. 34. I.S. Walker, M.H. Sherman, Energy Implications of Meeting ASHRAE Standard 62.2, ASHRAE Trans. 114 (2008) 505–521.

36

35. The new series of Malaysian Banknotes: Distinctively Malaysia,". [Online]. Available: http://www.bnm.gov.my/microsites/. Accessed: May. 5, 2017. 36. A. Chel, G.N. Tiwari, A. Chandra, Simplified method of sizing and life cycle cost assessment of building integrated photovoltaic system, Energy Build. 41 (2009) 1172–1180. 37. V. Raman, G.N. Tiwari,. A comparison study of energy and exergy performance of a hybrid photovoltaic double-pass and single-pass air collector, International Journal of Energy Research. 33(2009) 605–617. 38. P. Kongkiatumpai. Study of Impact of Indoor Set Point Temperature on Energy Consumption of Air-Conditioner and Green-House Gases Emission, King Mongkut’s University of Technology Thonburi: School of Energy and Materials, 1999. 39. "The new series of Malaysian Banknotes: Distinctively Malaysia,". [Online]. Available: http://www.bnm.gov.my/microsites/. Accessed: May. 5, 2017. 40. H. Nami, A. Nemati, M. Yari, F. Ranjbar, A comprehensive thermodynamic and exergoeconomic comparison between single- and two-stage thermoelectric cooler and heater, Appl. Therm. Eng. 124 (2017) 756–766. 41. R.plus

Peltier

Module

Hebei

TEC1-12730,

DEMO

https://www.electron.com/peltier-module-hebei-tec1-12730-p372/

Electron.com. (accessed

(n.d.).

August

30,

2016). 42. ELEGIANT Cooling Module, 7.1x3.9x1.8inch Aluminum Heat Sink Heatsink Cooler Fin for High

Power

LED

Amplifier

Transistor:

Beauty,

Amazon.

(n.d.).

https://www.amazon.com/ELEGIANT-7-1x3-9x1-8inch-Aluminum-AmplifierTransistor/dp/B01HMCYV80/ref=sr_1_2?s=beauty&ie=UTF8&qid=1535615303&sr=82&keywords=aluminium heat sink (accessed August 30, 2016). 43. A.H. Shamsuddin, Development of Renewable Energy in Malaysia-Strategic Initiatives for Carbon Reduction in the Power Generation Sector, Procedia Eng. 49 (2012) 384–391. 44. S.M. Shafie, H.H. Masjuki, T.M.I. Mahlia, Life cycle assessment of rice straw-based power generation in Malaysia, Energy. 70 (2014) 401–410. 37

45. R. Saidur, Energy consumption, energy savings, and emission analysis in Malaysian office buildings, Energy Policy. 37 (2009) 4104–4113. 46. "California carbon dashboard," 2006. [Online]. Available: http://calcarbondash.org/. Accessed: May. 5, 2017.

38

Highlights     

Sizing of room assisted TE-AD and PV-W systems is studies Life cycle assessment of TE-AD and PV-W systems is evaluated. Energy consumption analysis of three types of air cooling systems is provided. Emission and payback period of grid and PV assisted TE-AD system is introduced. PV TE-AD system provides long-term economic benefits as compared to other systems.

39