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Experimental investigation on using a novel phase change material (PCM) in micro structure photovoltaic cooling system
International Communications in Heat and Mass Transfer 100 (2019) 60–66
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International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt
Experimental investigation on using a novel phase change material (PCM) in micro structure photovoltaic cooling system
T
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Leila Siahkamaria, Masoud Rahimia, , Neda Azimib, Maysam Banibayata a b
CFD research center, Chemical Engineering Department, Razi University, Kermanshah, Iran Department of Chemical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
A R T I C LE I N FO
A B S T R A C T
Keywords: Photovoltaic Phase change material Cooling Nanoparticles
This work focused on experimental investigation of using a novel phase change material (PCM) in a PV module to enhance its cooling performance. Phase change material by absorbing a lot of heat from the surface of the PV module and control the heat capacitance of the system causes to raising its overall efficiency. In order to postpone the melting of the PCM material, copper microchannel tubes in which cold water is flowing is used and located in a chamber at the backside of the PV module. At first step of experiments, sheep fat has been used as a novel PCM and secondly; in order to increase the cooling efficiency of the sheep fat, CuO nanoparticles (0.004 (w/v)) have added to it. The results of the pure sheep fat and sheep fat+CuO nanoparticels have been compared with the layout of using paraffin wax as a conventional PCM. The obtained results of surface temperature, maximum power increase and electrical efficiency of the PV module for using each PCM materials have been compared. Results show that using both PCMs (sheep fat and paraffin wax) can enhance the cooling performance of the studied PV module; however, sheep fat is more efficient rather than the paraffin wax. In addition, results depicted that adding CuO nanoparticels in the sheep fat causes to significantly decrease in the average temperature of PV module surface. The research experiments of using sheep fat+CuO nanoparticels confirm that the maximum generated power is increased about 24.6% to 26.2% compared with the layout of no cooling system and 5.3% to 12% compared to paraffin wax.
1. Introduction Recently, much attention has been paid to solar energy as a major source of renewable energy which is cheap and always available [1–3]. The demand for cheap and plentiful energy has increased the usage of photovoltaic (PV) systems to direct electricity production from solar energy. The efficiency, productivity and the lifetime of the PV modules are significantly affected by exposed weather conditions such as wind speed, direction of the wind flow and ambient temperature [4]. It is reported in the literature that only about 15–20% of solar radiation that absorbed by the photovoltaic modules is changed to electricity and the residue is dissipated to heat [5]. There has been direct relation between the conversion efficiency and the surface temperature of photovoltaic modules and typical maximum values of the efficiency are reached between 14% and 17% [4]. It was reported in the literature that each 1 °C increase in the surface temperature of solar cells causes to 0.5% f decrease in the efficiency of the PV modules [6–8]. It is seriously required to find the efficient cooling techniques to remove higher amounts of heat from the PV modules. Some active and passive
⁎
techniques that have been used to enhance the cooling performance of the PV modules [1,2,9–19]. One simple technique is cooling by phase change materials (PCMs) which they are applicable materials to control and manage the heat. This is because during the process of the melting and freezing of PCM (phase change), thermal energy storage and release [20]. During the freezing of a PCM, large amounts of energy in the form of latent heat of fusion releases. Conversely, when a PCM is melted, an equal amount of released energy in freezing process is absorbed to change the PCM from the solid to the liquid phase. This feature of PCMs can be applied for thermal energy storage whereby heat or coolness can be congested from one process or period in time. However, for using PCM in the PV modules as cooling method, the effect of PCM property is an important topic. Paraffin wax is an inexpensive, non-toxic, environmentally friendly and a commonly phase change material. Paraffin wax is used for heat storage in the PV modules due to the high storage capacity and ability to contains a high amount of heat in a wide range of temperature [21]. There are several studies focused on combining PV systems and PCM or nanofluids. However, this studies space needs
Corresponding author at: Chemical Engineering Department, Razi University, Taghe Bostan, Kermanshah, Iran. E-mail address: [email protected] (M. Rahimi).
https://doi.org/10.1016/j.icheatmasstransfer.2018.12.020
0735-1933/ © 2018 Elsevier Ltd. All rights reserved.
International Communications in Heat and Mass Transfer 100 (2019) 60–66
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further reasearch to provide the efficient feasible solution to increase the efficiency of photovoltaic collectors. Huang et al. [22] experimentally and numerically investigated the effect of a PCM on the building integrated PV, by increasing the efficiency of the PV module and capitalizing on the lost temperature. The temperatures distribution, velocity fields and vortex formation inside the system obtained by numerical modeling were compared to experimental data. Karunamurthy et al. [23] dispersed CuO nanoparticles in paraffin wax as a commonly PCM to boost its thermal conductivity. In another study, CFD modeling of heat and mass transfer in a PV panel incorporating an impure phase change have been performed by Biwole et al. [24]. The simulation depicted that a used PCM can maintain the panel temperature under 40 °C for approximately 80 minets under a constant solar radiation of 1 kW/m2. Stropnik and Stritih [13] numerically investigated the influences of application of PCM in a photovoltaic/thermal system (PV/T) on its electrical efficiency. The panel temperature obtained in the numerical modeling compared with experimental data. The results show that for a one-year period, the power generation of the PV/T system with PCM was 7.3% higher than PV/T with no cooling system. Su et al. [25] performed a comparative analyses on a hybrid PT/T system composed of the phase change materials with different melting point. It was found that using PCM with lower melting point show higher overall energy output in PV/T system. Sardarabadi et al. [26] investigated an experimental study on using paraffin wax as PCM and a ZnO-nanofluid for cooling enhancement of a PV/T system. The nanofluid flows in the copper pipes that were emerged in the PCM storage tank. The results show that using PCM has increased the generated power of PV/T 13% over the conventional PV system. Another study has been done by Mousavi et al. [27], in which they investigated the cooling performance of five different PCMs in metal foam as porous medium on the thermal efficiency of a PV/T system. The highest thermal efficiency of PV/T system was related to Paraffin C22 and the integration of the porous medium resulted in better temperature distribution. Preet et al. [28] gathered a valuable review of various methods related to using phase change material in PV/T and PV systems for improving performance of photovoltaic/thermal system.It was reported that using phase change material is proficient solution for cooling of photovoltaic panel. The main purpose of this study was to investigate using sheep fat as a novel PCM material for photovoltaic applications, i.e. for possible efficient thermal management of PVs. Copper microchannel tubes that located in a chamber at the backside of the PV module and in which cold water is flowing, has been used to postpone the melting of the PCM material. In order to increase the cooling efficiency of the sheep fat, CuO nanoparticles (0.004 (w/v)) have been added to it and the results of sheep fat and sheep fat+CuO nanoparticles have been compared with the layout of using paraffin wax as a conventional PCM. The obtained results of surface temperature, maximum power increase and electrical efficiency of the PV module for using PCM materials have been investigated.
Fig. 1. A schematic diagram of the experimental setup used in the present work. Table 1 The major components and the characteristics of test apparatus in this study. Photovoltaic cell specification Model Dimensions Rate maximum power (Pmax) Voltage at Pmax (Vm) Current at Pmax (Im) Open-circuit voltage (Voc) Short-circuit current (Isc) Nominal operating cell temp Cell technology Application class Output tolerance
BTM-4208SD 360×275 ×16 mm 10
ACDC, Taiwan mm Watt
17.85 0.62 21.77 0.59 45 ± 2
Volt Ampere Volt Ampere °C
Poly-Si C ± 3%
Thermometer Temperature range Type Model
−50.0 to 999.9 °C ± 0.5 °C Lutron BTM-4208SD
Accuracy ± 0.4%
Tes1333R
Accuracy ± 2%
400 6 l HID-T400 W/D
Watt Piece
Pyranometer Model Metal Halide lamp
2. Experimental work
Power Issue Model
2.1. Apparatus and data acquisition system and experiment procedures An experimental setup is designed to discover the influences of using PCMs on the efficiency of a PV system. A schematic diagram of the experimental setup used in the present study is depicted in Fig. 1. The basic components of the experimental setup are consisting of PV module, solar simulator, reservoir and data acquisition system. PV module is a mono-crystalline silicon photovoltaic module with the active area of 26 mm × 30 mm for each matrix. The used PV module is consisting of 72 cells connected in parallel and series. Table 1 depicted the major components and the characteristics of experiment apparatus in the present work. A steel frame is used to handle the PV module under light of halide lumps at constant position toward them. The average surface temperature of PV module was obtained by measuring
the temperature of 9 points on the PV module surface using a thermometer (Lutron, BTM-4208SD). For this purpose, 9 thermocouples have been attached on the surface of PV module. An electrical load system connected to the PV electrical output is used to measure and record PV voltage and I–V data. PCM located in a chamber at the back of the PV module is cooled with copper microchannel tubes. In order to cool the PCM, copper microchannel tubes in which cold water is flowing have been used. The copper tubes are connected to two big copper tubes and placed in the backside of the PV module. The schematic of the cross-section of PV module and the copper microchannel 61
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Fig. 2. Schematic views from cooling system (a) Cross-section of the PV module and the copper microchannel tubes surrounded by PCM-CuO nanoparticels (b) positions of copper tubes located in the backside of the PV module.
temperature (23 °C) and the constant radiation intensity of 1000 W/m2. The results of pure sheep fat and sheep fat+CuO nanoparticles have been compared with the layout of using paraffin as a conventional PCM.
tubes surrounded by PCM-CuO nanoparticles can be seen in Fig. 2 (a). In addition, Fig. 2 (b) shows the positions of copper tubes are located in the backside of the PV module. The cold water is removed from the tank and into one big copper tube and is removed from the big copper tube. In order to have copper microchannel tubes filled with water during the tests, the PV module has a gradient horizon of 15 °C and cold water is introduced into a lower big copper tube. A solar imitator is designed and used to simulate the required solar irradiation. Forasmuch as, the sunlight is not persistently usable; six Metal Halide (MH) lamps are used to generate a continuous spectrum of light. Prior to doing experiments, the leak-tested for water flowing in copper tubes is accomplished at the highest water flow rate of water. After resolving of all leaks, water pump and the halide lamps in solar simulator are switched. For each experiment, a specific amount of PCM is poured into the reservoir in the backside of PV module and restored to the system for 24 h to form the solid. When performing the tests, the cold water input is set to the desired value. All the experiments have been done at the room
2.2. Properties of the sheep fat and the paraffin wax as PCMs In order to reduce PV panel operating temperatures, two types of PCMs including sheep fat and paraffin wax are considered for passive cooling configurations (PV-PCM). The novelty of this research is the general idea of using sheep fat as an organic PCM material for PV-PCM applications. Sheep fat as a PCM material is an organic material (thus more environmentally friendly) and which has got a significantly lower initial cost (unit price). Table 2 represents the tested paraffin wax and sheep fat specifications.
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Table 2 Physical properties of paraffin wax and sheep fat.
95
without cooling
Specifications
90
Parrafin
Sheep fat
85
Paraffin wax
Manufacturer
Iran
Melting point temperature (°C) Latent heat of fusion (kJ/kg) Solid state density (kg/m3) Liquid state density (kg/m3) Thermal conductivity (W/m °C) Solid state specific heat (kJ/ kg °C) Liquid state specific heat (kJ/ kg °C)
47 180 918 830 0.312 2.04
Haya chemical company, Kermanshah, Iran. 53 198 932 838 0.21 2.1
2.04
2.1
Sheep fat Sheep fat+CuO
80 75
Tsurface (ºC)
Material properties
70 65 60 55 50 45 40 35
2.3. Preparation of sheep fat nanosuspension
30
In this work, CuO Nanopowder with the diameter and density of < 50 nm and 6300 kg/m3 (purity of 99.5%), respectively, is supplied by Sigma-Aldrich Company. CuO nanoparticles are used because of their specific characteristics and high electrical conductivity. The sheep fat has been used as a novel PCM and in order to increase the cooling efficiency of sheep fat, CuO nanoparticles (0.004 (w/v)) have added to it. In order to prepare the suspension of sheep fat+CuO nanoparticles, the quantities of nanoparticles required for 0.004 (w/v) concentrations of CuO/melted sheep fat nanofluid for a total volume of 2 L are calculated and well dispersed in sheep fat as the base liquid. At first, a specified weight of CuO nanoparticles is added to sheep fat with constant stirring for 30 min. After that, in order to obtain a uniformly dispersed solution and to prevent CuO nanoparticles from settling, the prepared nanofluid is sonicated by an ultrasonic homogenizer (Hielscher UP400S, Germany) at a frequency of 24 kHz and a nominal power of 400 W at the controlled temperature of 293–298 K for 80 min. In addition, since the cold-water flows in microchannels are placed within the phase change material, so; the cooling water does not allow PCM to melt significantly and lose viscosity. Therefore, the composition of CuO nanoparticles and sheep fat is approximately stable and nanoparticles cannot precipitate.
0
10
20
30
40
50
60
70
80
Time (min) Fig. 3. Variation of the average temperature of the PV module surface without cooling and using PCMs (Q = 6 mL/s).
and the system reached a stable state. The reason for the temperature decrease of the PV module surface in the use of pure paraffin and sheep fat is the absorption of excess heat from its surface by the phase change material. As shown in Fig. 3, the use of sheep fat in comparison with paraffin led to a further decrease in the surface temperature of the PV module and it reached from 77.2 °C to 70 °C. Therefore, it can be concluded that sheep fat is a potential PCM material for the considered passive cooling technique. Regarding general thermal management issues, it is clear that a sheep fat is somewhat better when compared to the conventional PCM material such as paraffin. In addition, according to Fig. 5, it is observed that by adding nanoparticles to sheep fat, the temperature of the PV module surface has decreased and reaches to 63 °C. The presence of copper oxide nanoparticles in the sheep fat as the phase change material leads to an increase in its thermal conductivity and increases the absorption capacity of the heat.
3.2. Effect of water flow rate on the surface temperature of PV module 3. Results and discussion As stated above, in order to postpone the melting of the PCMs, copper tubes in which cold water flows is used. Copper pipes are located with the distance from the module surface and not in contact, and only serves to cool the PCM material in the molten state. Fig. 4 shows the effect of water flow rate (Q) flows in the copper tubes surrounded by PCM on the temperature changes of the PV module surface. In fact, cold water inside the copper tubes is used to exchange heat transfer with PCM. By increasing the surface temperature of the PV module to more than the melting point of PCM, the melting point will begin. Therefore, by flowing cold water into the copper tubes, PCM can be restored to solid state again, and the surface-heat exchange process of the PV module to PCM will continue and change its state. According to the figure, the increase in water flow rate has led to a decrease in the surface temperature of the PV module, which it is owing to preventing of the melting of PCM. In fact, increasing (Q) will increase the heat transfer rate between the water and the PCM around the tubes, and thus improve PCM performance to reduce the surface temperature of the PV module. In addition, in Fig. 4, the comparison between the surface temperatures of the PV module for all three used PCMs shows that in the case of using sheep fat+CuO nanoparticles, the surface temperature of the module is less than the other two, which is consistent with the previous results.
3.1. PV module temperature without cooling and using PCMs Initially, the experiments were performed for the non-cooling system and all data were recorded, including module surface temperature, voltage and current. For the layout of no cooling system, Fig. 3 shows the 9-point temperatures of the PV module surface, as well as the mean of them, over time, to reach a steady state in the absence of a cooling system. According to this figure, the average temperature at the module surface is roughly after 65 min reaches to steady state and the maximum average temperature of the module after 65 min is about 83.3 °C. In the next steps, paraffin, sheep fat and sheep fat+CuO nanoparticles were poured into the reservoir at the backside of the PV module and experiments were repeated to examine the effect of phase change materials on the reducing of the surface temperature of the PV module. In all these steps, the module temperatures were captured as long as the system became stable. Initially, the cold water discharge (Q) was adjusted to 6 mL/s and the amount of 1 kg of each PCM was used to perform the experiments. Fig. 3 shows that with regard to using of pure paraffin and sheep fat and sheep fat +CuO nanoparticles, the surface temperature of the PV module decreased significantly and the slope of the temperature increase was decreased. After 65 min, the surface temperatures of the PV module for the use of all three PCMs were fixed 63
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80 75
Parrafin
24
Sheep fat
22
Sheep fat+CuO
20
70
18 16 14
Voltage (V)
Tsurface (ºC)
65 60
12 10
55
8 6
50
4 2
45
0
40
Without cooling Paraffin Sheep fat Sheep Fat+CuO
0
5
10
15
20
25
30
0
0.05
0.1
0.15
0.2
0.25
35
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
Current (A)
Q (mL/min)
(a) 6
Fig. 4. Effect of water flow rate (Q) on the average temperature of the PV module using PCMs.
Without cooling Paraffin
3.3. Module electrical performance
Sheep Fat+CuO
In order to investigate the effects of phase change material on the generation of electricity by the PV module, its performance without cooling system is first evaluated. Then, I–V data from experiments are collected for three different types of PCMs. V–I experimental data for the standard time range for the without cooling system mode and at the minimum flow rate of the water is shown in Fig. 5 (a). As shown in this figure, the area under the V–I curve increases by using all three types of PCM materials. As the area under the V–I curve shows the power generation of PV module, these results indicate an increase in the output power of the PV module for case of the using sheep fat+CuO nanoparticles compared to pure paraffin and sheep fat. Here, from the V–I values of the studied solar cell in the experiments, it is necessary to define and calculate the generated power from the PV module as follow: The maximum generated power by the PV module (Pmax) can be calculated as follows [16,18]:
PPV = IPV × VPV
Sheep fat
5
Power (w)
4
3
2
1
0
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 Voltage (V)
(b)
(1)
Fig. 5. Output power characteristics curves of PV module for using different PCMs and without cooling layout (Q = 6 mL/s). (a) voltage-current curve, (b) power-voltage curve.
The generated power from the PV module, which works with sheep fat+CuO, is depicted as a function of the output voltage in Fig. 5 (b). As expected, with using each PCM, there is a clear trend in increasing production capacity. The comparison between results of output power obtained for no cooling system and the presence of PCMs could highlight the effect of using phase change materials on the performance of the PV module with water as working cold fluid in better way. In addition, from Fig. 5 (b) it can be conclude that for the layout of using sheep fat as PCM, the PV module achieves higher power output rather than paraffin. According to this figure, the maximum output power is belongs to the PV-sheep fat+CuO system and it is 5.32 watts, which corresponds to a voltage of 14 V. The V–I experimental data and generated power as a function of outlet voltage for the PV module cooled with sheep fat+CuO and Q = 6–31 mL/s is plotted in Fig. 6. As shown in Fig. 6 (a), the area under the V–I curve increases by increase in the flow rate of cold water. Since, the area under the V–I curve is equal to the power generation of PV module, these figure shows an increase in the output power of the PV module for increasing the flow rate of cold water because of increase in postponing the melting time of the sheep fat. As it can be seen in Fig. 6 (b), there is a clear trend of increasing in the generated power from the PV module by increasing the water flow rate. As mentioned above, by increasing Q, the heat transfer rate between the water and the
PCM around the copper tubes increased, and thus leads to improve the PCM performance to reduce the surface temperature of the PV module. In this study, Eq. (2) is used for calculating of increase in the Pmax, which is defined as follow:
PPCM − Pwithout cooling ⎞ P(max) increase = ⎜⎛ ⎟ × 100 Pwithout cooling ⎝ ⎠
(2)
The percentage increase in the electrical PV output for all three PCMs at different water flow rates are presented in Fig. 7. The obtained results for water flow rate (Q) from 6 to 31 (mL/s) shows that by increasing Q, the percentage of maximum power increase, raises remarkably for all of the PCMs. It can be seen that the higher electrical efficiency (26.2%) is obtained with Q = 31 (mL/s) for using sheep fat +CuO nanoparticles, as the lowest average temperature of the PV module occurred in this layout. However, for the pure sheep fat, by increasing the water flow rate, the electrical efficiency has low changes. 4. Conclusions The experimental study has been conducted to investigate the effect 64
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30
24 Q=10 mL/s
20
26
Q=16.5 mL/s
Maximum power increase (%)
Q=26 mL/s
18
Q=31 mL/s
16 Voltage (V)
Q=6 mL/s Q=10 mL/s Q=16.5 mL/s Q=26 mL/s Q=31 mL/s
Q=6 mL/s
22
14 12 10 8 6 4
22
18
14
10
2 0
6 0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 Current (A)
2
(a) 7
Q=10 mL/s
Nomenclatures
Q=26 mL/s
Power (w)
Sheep fat+CuO
Q=16.5 mL/s
5
Q=31 mL/s
I IPV Pmax PPCM PPV Pwithout TPCM VPV
4
3
2
1
0
Sheep fat
Fig. 7. % Maximum power increase for the PV module at the different water flow rate for different PCMs.
Q=6 mL/s
6
Paraffin
Average intensity on absorber plate (W/m2) Photovoltaic arrays current (A) Maximum power of photovoltaic arrays (W) Power of photovoltaic arrays by cooling with PCM (W) Photovoltaic arrays power (W) cooling Reference power (W) Temperature of photovoltaic arrays by using PCM (°C) Photovoltaic arrays voltage (v)
Subscripts max 0
1
2
3
4
5
6
7
8
Maximum
9 10 11 12 13 14 15 16 17 18 19 20 21 22 Voltage (V)
Abbreviations
(b)
PV
Fig. 6. Effect of water flow rate on the Output power characteristics curves for sheep fat+ CuO suspension. (a) voltage-current curve, (b) power-voltage curve.
Photovoltaic
References
of using a novel phase change material (PCM) on the cooling performance of a PV module. Firstly, the surface average temperature of PV cell without cooling system as a reference system has been recorded based on time to reach the surface temperature at steady condition. Secondly, the effects of using paraffin wax and sheep fat as PCMs have been experimentally evaluated. The sheep fat has been used as a novel PCM and in order to increase its cooling efficiency, CuO nanoparticles (0.004 (w/v)) have been added to the sheep fat. The effect of using sheep fat+CuO nanoparticels for decrease in the surface average temperature of the PV module, power generated and electrical outputs of the systems as the critical parameters have been compared with the case of paraffin wax and pure sheep fat. Results depicted that using both PCMs has high capability for improving the cooling performance of the studied the PV module. Moreover, results show that using sheep fat +CuO nanoparticels significantly decreased the average temperature of the PV module surface compared to the cases of not cooling system and using pure sheep fat. Simultaneous use of PCM and CuO nanoparticles lead to increase in the percentage of maximum power increase from 24.6–26.2% related to flow rate of water flowing in microchannel tubes.
[1] N. Heidari, M. Rahimi, N. Azimi, Experimental investigation on using ferrofluid and rotating magnetic field (RMF) for cooling enhancement in a photovoltaic cell, Int. Commun. Heat Mass Transf. 94 (2018) 32–38. [2] M. Ebrahimi, M. Rahimi, A. Rahimi, An experimental study on using natural vaporization for cooling of a photovoltaic solar cell, Int. Commun. Heat Mass Transf. 65 (2015) 22–30. [3] S.S. Chandel, Tanya Agarwal, Review of cooling techniques using phase change materials for enhancing efficiency of photovoltaic power systems, Renew. Sust. Energ. Rev. 73 (2017) 1342–1351. [4] C.G. Popovici, S.V. Hudișteanu, T.D. Mateescu, N.C. Cherecheș, Efficiency improvement of photovoltaic panels by using air cooled heat sinks, Energy Procedia 85 (2016) 425–432. [5] M. Emam, S. Ookawara, M. Ahmed, Performance study and analysis of an inclined concentrated photovoltaic-phase change material system, Sol. Energy 150 (2017) 229–245. [6] M. Sardarabadi, M. Passandideh-Fard, S. Zeinali Heris, Experimental investigation of the effects of silica/water nanofluid on PV/T (photovoltaic thermal units), Energy 66 (2014) 264–272. [7] M. Ghadiri, M. Sardarabadi, M. Pasandideh-fard, A.J. Moghadam, Experimental investigation of a PVT system performance using nano Ferrofluids, Energy Convers. Manag. 103 (2015) 468–476. [8] S.A. Kalogirou, Y. Tripanagnostopoulos, Hybrid PV/T solar systems for domestic hot water and electricity production, Energy Convers. Manag. 47 (2006) 3368–3382. [9] Y. Su, Y. Zhang, L. Shu, Experimental study of using phase change material cooling in a solar tracking concentrated photovoltaic-thermal system, Sol. Energy 159 (2018) 777–785. [10] S. Preet, B. Bhushan, T. Mahajan, Experimental investigation of water based
65
International Communications in Heat and Mass Transfer 100 (2019) 60–66
L. Siahkamari et al.
[11]
[12] [13] [14]
[15] [16] [17] [18]
[19]
[20]
photovoltaic/thermal (PV/T) system with and without phase change material (PCM), Sol. Energy 155 (2017) 1104–1120. J. Barrau, J. Rosell, D. Chemisana, L. Tadrist, M. Ibaoez, Effect of a hybrid jet impingement/micro-channel cooling device on the performance of densely packed PV modules under high concentration, Sol. Energy 85 (2011) 2655–2665. M. Rahimi, E. Karimi, M. Asadi, P.V. Sheyda, Heat transfer augmentation in a hybrid microchannel solar cell, Int. Commun. Heat Mass Transf. 43 (2013) 131–137. R. Stropnik, U. Stritih, Increasing the efficiency of PV panel with the use of PCM, Renew. Energy 97 (2016) 671–679. M. Sardarabadi, M. Hosseinzadeh, A. Kazemian, M. Passandideh-Fard, Experimental investigation of the effects of using metal-oxides/water nanofluids on a photovoltaic thermal system (PVT) from energy and exergy viewpoints, Energy 138 (2017) 682–695. S. Dong, T.M. Shih, W. Lin, X. Cai, R.R.G. Chang, Z. Chen, Time-dependent photovoltaic-thermoelectric hybrid systems, Numer. Heat Transf. A 66 (2014) 402–419. N. Karami, M. Rahimi, Heat transfer enhancement in a PV module using Boehmite nanofluid, Energy Convers. Manag. 86 (2014) 275–285. S. Agrawal, A. Tiwari, A, Experimental validation of glazed hybrid micro-channel solar cell thermal tile, Sol. Energy 85 (2011) 3046–3056. N. Karami, M. Rahimi, Heat transfer enhancement in a hybrid microchannel-photovoltaic module using Boehmite nanofluid, Int. Commun. Heat Mass Transf. 55 (2014) 45–52. S. Nižetić, M. Arıcı, F. Bilgin, F. Grubišić-Čabo, Investigation of pork fat as potential novel phase change material for passive cooling applications in photovoltaics, J. Clean. Prod. 170 (2017) 1006–1016. M.J. Hosseini, A.A. Ranjbar, K. Sedighi, M. Rahimi, A combined experimental and computational study on the melting behavior of a medium temperature phase
[21]
[22]
[23]
[24] [25]
[26]
[27]
[28]
66
change storage material inside shell and tube heat exchanger, Int. Commun. Heat Mass Transf. 39 (2012) 1416–1424. A.H.A. Al-Waeli, K. Sopian, M.T. Chaichan, H.A. Kazem, A. Ibrahim, S. Mat, M.H. Ruslan, Evaluation of the nanofluid and nano-PCM based photovoltaic thermal (PVT) system: an experimental study, Energy Convers. Manag. 151 (2017) 693–708. M.J. Huang, P.C. Eames, B. Norton, Thermal regulation of building-integrated photovoltaics using phase change materials, Int. J. Heat Mass Transf. 47 (2004) 2715–2733. K. Karunamurthy, K. Murugumohankumar, S. Suresh, Use of CuO nanomaterial for the improvement of thermal conductivity and performance of low temperature energy storage system of solar pond, Digest J. Nanomater. Biostruct. 7 (2012) 1833–1841. P.H. Biwole, P. Eclache, F. Kuznik, Phase-change materials to improve solar panel's performance, Energ. Build. 62 (2013) 59–67. D. Su, Y. Jia, Y. Lin, G. Fang, Maximizing the energy output of a photovoltaic–thermal solar collector incorporating phase change materials, Energ. Build. 153 (2017) 382–391. M. Sardarabadi, M. Passandideh-Fard, M.J. Maghrebi, M. Ghazikhani, Experimental study of using both ZnO/water nanofluid and phase change material (PCM) in photovoltaic thermal systems, Sol. Energy Mater. Sol. Cells 161 (2017) 62–69. S. Mousavi, A. Kasaeian, M.B. Shafii, M.H. Jahangir, Numerical investigation of the effects of a copper foam filled with phase change materials in a water-cooled photovoltaic/thermal system, Energy Convers. Manag. 163 (2018) 187–195. S. Preet, Water and phase change material based photovoltaic thermal management systems: a review, Renew. Sust. Energ. Rev. 82 (2018) 791–807.
Contents lists available at ScienceDirect
International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt
Experimental investigation on using a novel phase change material (PCM) in micro structure photovoltaic cooling system
T
⁎
Leila Siahkamaria, Masoud Rahimia, , Neda Azimib, Maysam Banibayata a b
CFD research center, Chemical Engineering Department, Razi University, Kermanshah, Iran Department of Chemical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
A R T I C LE I N FO
A B S T R A C T
Keywords: Photovoltaic Phase change material Cooling Nanoparticles
This work focused on experimental investigation of using a novel phase change material (PCM) in a PV module to enhance its cooling performance. Phase change material by absorbing a lot of heat from the surface of the PV module and control the heat capacitance of the system causes to raising its overall efficiency. In order to postpone the melting of the PCM material, copper microchannel tubes in which cold water is flowing is used and located in a chamber at the backside of the PV module. At first step of experiments, sheep fat has been used as a novel PCM and secondly; in order to increase the cooling efficiency of the sheep fat, CuO nanoparticles (0.004 (w/v)) have added to it. The results of the pure sheep fat and sheep fat+CuO nanoparticels have been compared with the layout of using paraffin wax as a conventional PCM. The obtained results of surface temperature, maximum power increase and electrical efficiency of the PV module for using each PCM materials have been compared. Results show that using both PCMs (sheep fat and paraffin wax) can enhance the cooling performance of the studied PV module; however, sheep fat is more efficient rather than the paraffin wax. In addition, results depicted that adding CuO nanoparticels in the sheep fat causes to significantly decrease in the average temperature of PV module surface. The research experiments of using sheep fat+CuO nanoparticels confirm that the maximum generated power is increased about 24.6% to 26.2% compared with the layout of no cooling system and 5.3% to 12% compared to paraffin wax.
1. Introduction Recently, much attention has been paid to solar energy as a major source of renewable energy which is cheap and always available [1–3]. The demand for cheap and plentiful energy has increased the usage of photovoltaic (PV) systems to direct electricity production from solar energy. The efficiency, productivity and the lifetime of the PV modules are significantly affected by exposed weather conditions such as wind speed, direction of the wind flow and ambient temperature [4]. It is reported in the literature that only about 15–20% of solar radiation that absorbed by the photovoltaic modules is changed to electricity and the residue is dissipated to heat [5]. There has been direct relation between the conversion efficiency and the surface temperature of photovoltaic modules and typical maximum values of the efficiency are reached between 14% and 17% [4]. It was reported in the literature that each 1 °C increase in the surface temperature of solar cells causes to 0.5% f decrease in the efficiency of the PV modules [6–8]. It is seriously required to find the efficient cooling techniques to remove higher amounts of heat from the PV modules. Some active and passive
⁎
techniques that have been used to enhance the cooling performance of the PV modules [1,2,9–19]. One simple technique is cooling by phase change materials (PCMs) which they are applicable materials to control and manage the heat. This is because during the process of the melting and freezing of PCM (phase change), thermal energy storage and release [20]. During the freezing of a PCM, large amounts of energy in the form of latent heat of fusion releases. Conversely, when a PCM is melted, an equal amount of released energy in freezing process is absorbed to change the PCM from the solid to the liquid phase. This feature of PCMs can be applied for thermal energy storage whereby heat or coolness can be congested from one process or period in time. However, for using PCM in the PV modules as cooling method, the effect of PCM property is an important topic. Paraffin wax is an inexpensive, non-toxic, environmentally friendly and a commonly phase change material. Paraffin wax is used for heat storage in the PV modules due to the high storage capacity and ability to contains a high amount of heat in a wide range of temperature [21]. There are several studies focused on combining PV systems and PCM or nanofluids. However, this studies space needs
Corresponding author at: Chemical Engineering Department, Razi University, Taghe Bostan, Kermanshah, Iran. E-mail address: [email protected] (M. Rahimi).
https://doi.org/10.1016/j.icheatmasstransfer.2018.12.020
0735-1933/ © 2018 Elsevier Ltd. All rights reserved.
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further reasearch to provide the efficient feasible solution to increase the efficiency of photovoltaic collectors. Huang et al. [22] experimentally and numerically investigated the effect of a PCM on the building integrated PV, by increasing the efficiency of the PV module and capitalizing on the lost temperature. The temperatures distribution, velocity fields and vortex formation inside the system obtained by numerical modeling were compared to experimental data. Karunamurthy et al. [23] dispersed CuO nanoparticles in paraffin wax as a commonly PCM to boost its thermal conductivity. In another study, CFD modeling of heat and mass transfer in a PV panel incorporating an impure phase change have been performed by Biwole et al. [24]. The simulation depicted that a used PCM can maintain the panel temperature under 40 °C for approximately 80 minets under a constant solar radiation of 1 kW/m2. Stropnik and Stritih [13] numerically investigated the influences of application of PCM in a photovoltaic/thermal system (PV/T) on its electrical efficiency. The panel temperature obtained in the numerical modeling compared with experimental data. The results show that for a one-year period, the power generation of the PV/T system with PCM was 7.3% higher than PV/T with no cooling system. Su et al. [25] performed a comparative analyses on a hybrid PT/T system composed of the phase change materials with different melting point. It was found that using PCM with lower melting point show higher overall energy output in PV/T system. Sardarabadi et al. [26] investigated an experimental study on using paraffin wax as PCM and a ZnO-nanofluid for cooling enhancement of a PV/T system. The nanofluid flows in the copper pipes that were emerged in the PCM storage tank. The results show that using PCM has increased the generated power of PV/T 13% over the conventional PV system. Another study has been done by Mousavi et al. [27], in which they investigated the cooling performance of five different PCMs in metal foam as porous medium on the thermal efficiency of a PV/T system. The highest thermal efficiency of PV/T system was related to Paraffin C22 and the integration of the porous medium resulted in better temperature distribution. Preet et al. [28] gathered a valuable review of various methods related to using phase change material in PV/T and PV systems for improving performance of photovoltaic/thermal system.It was reported that using phase change material is proficient solution for cooling of photovoltaic panel. The main purpose of this study was to investigate using sheep fat as a novel PCM material for photovoltaic applications, i.e. for possible efficient thermal management of PVs. Copper microchannel tubes that located in a chamber at the backside of the PV module and in which cold water is flowing, has been used to postpone the melting of the PCM material. In order to increase the cooling efficiency of the sheep fat, CuO nanoparticles (0.004 (w/v)) have been added to it and the results of sheep fat and sheep fat+CuO nanoparticles have been compared with the layout of using paraffin wax as a conventional PCM. The obtained results of surface temperature, maximum power increase and electrical efficiency of the PV module for using PCM materials have been investigated.
Fig. 1. A schematic diagram of the experimental setup used in the present work. Table 1 The major components and the characteristics of test apparatus in this study. Photovoltaic cell specification Model Dimensions Rate maximum power (Pmax) Voltage at Pmax (Vm) Current at Pmax (Im) Open-circuit voltage (Voc) Short-circuit current (Isc) Nominal operating cell temp Cell technology Application class Output tolerance
BTM-4208SD 360×275 ×16 mm 10
ACDC, Taiwan mm Watt
17.85 0.62 21.77 0.59 45 ± 2
Volt Ampere Volt Ampere °C
Poly-Si C ± 3%
Thermometer Temperature range Type Model
−50.0 to 999.9 °C ± 0.5 °C Lutron BTM-4208SD
Accuracy ± 0.4%
Tes1333R
Accuracy ± 2%
400 6 l HID-T400 W/D
Watt Piece
Pyranometer Model Metal Halide lamp
2. Experimental work
Power Issue Model
2.1. Apparatus and data acquisition system and experiment procedures An experimental setup is designed to discover the influences of using PCMs on the efficiency of a PV system. A schematic diagram of the experimental setup used in the present study is depicted in Fig. 1. The basic components of the experimental setup are consisting of PV module, solar simulator, reservoir and data acquisition system. PV module is a mono-crystalline silicon photovoltaic module with the active area of 26 mm × 30 mm for each matrix. The used PV module is consisting of 72 cells connected in parallel and series. Table 1 depicted the major components and the characteristics of experiment apparatus in the present work. A steel frame is used to handle the PV module under light of halide lumps at constant position toward them. The average surface temperature of PV module was obtained by measuring
the temperature of 9 points on the PV module surface using a thermometer (Lutron, BTM-4208SD). For this purpose, 9 thermocouples have been attached on the surface of PV module. An electrical load system connected to the PV electrical output is used to measure and record PV voltage and I–V data. PCM located in a chamber at the back of the PV module is cooled with copper microchannel tubes. In order to cool the PCM, copper microchannel tubes in which cold water is flowing have been used. The copper tubes are connected to two big copper tubes and placed in the backside of the PV module. The schematic of the cross-section of PV module and the copper microchannel 61
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Fig. 2. Schematic views from cooling system (a) Cross-section of the PV module and the copper microchannel tubes surrounded by PCM-CuO nanoparticels (b) positions of copper tubes located in the backside of the PV module.
temperature (23 °C) and the constant radiation intensity of 1000 W/m2. The results of pure sheep fat and sheep fat+CuO nanoparticles have been compared with the layout of using paraffin as a conventional PCM.
tubes surrounded by PCM-CuO nanoparticles can be seen in Fig. 2 (a). In addition, Fig. 2 (b) shows the positions of copper tubes are located in the backside of the PV module. The cold water is removed from the tank and into one big copper tube and is removed from the big copper tube. In order to have copper microchannel tubes filled with water during the tests, the PV module has a gradient horizon of 15 °C and cold water is introduced into a lower big copper tube. A solar imitator is designed and used to simulate the required solar irradiation. Forasmuch as, the sunlight is not persistently usable; six Metal Halide (MH) lamps are used to generate a continuous spectrum of light. Prior to doing experiments, the leak-tested for water flowing in copper tubes is accomplished at the highest water flow rate of water. After resolving of all leaks, water pump and the halide lamps in solar simulator are switched. For each experiment, a specific amount of PCM is poured into the reservoir in the backside of PV module and restored to the system for 24 h to form the solid. When performing the tests, the cold water input is set to the desired value. All the experiments have been done at the room
2.2. Properties of the sheep fat and the paraffin wax as PCMs In order to reduce PV panel operating temperatures, two types of PCMs including sheep fat and paraffin wax are considered for passive cooling configurations (PV-PCM). The novelty of this research is the general idea of using sheep fat as an organic PCM material for PV-PCM applications. Sheep fat as a PCM material is an organic material (thus more environmentally friendly) and which has got a significantly lower initial cost (unit price). Table 2 represents the tested paraffin wax and sheep fat specifications.
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Table 2 Physical properties of paraffin wax and sheep fat.
95
without cooling
Specifications
90
Parrafin
Sheep fat
85
Paraffin wax
Manufacturer
Iran
Melting point temperature (°C) Latent heat of fusion (kJ/kg) Solid state density (kg/m3) Liquid state density (kg/m3) Thermal conductivity (W/m °C) Solid state specific heat (kJ/ kg °C) Liquid state specific heat (kJ/ kg °C)
47 180 918 830 0.312 2.04
Haya chemical company, Kermanshah, Iran. 53 198 932 838 0.21 2.1
2.04
2.1
Sheep fat Sheep fat+CuO
80 75
Tsurface (ºC)
Material properties
70 65 60 55 50 45 40 35
2.3. Preparation of sheep fat nanosuspension
30
In this work, CuO Nanopowder with the diameter and density of < 50 nm and 6300 kg/m3 (purity of 99.5%), respectively, is supplied by Sigma-Aldrich Company. CuO nanoparticles are used because of their specific characteristics and high electrical conductivity. The sheep fat has been used as a novel PCM and in order to increase the cooling efficiency of sheep fat, CuO nanoparticles (0.004 (w/v)) have added to it. In order to prepare the suspension of sheep fat+CuO nanoparticles, the quantities of nanoparticles required for 0.004 (w/v) concentrations of CuO/melted sheep fat nanofluid for a total volume of 2 L are calculated and well dispersed in sheep fat as the base liquid. At first, a specified weight of CuO nanoparticles is added to sheep fat with constant stirring for 30 min. After that, in order to obtain a uniformly dispersed solution and to prevent CuO nanoparticles from settling, the prepared nanofluid is sonicated by an ultrasonic homogenizer (Hielscher UP400S, Germany) at a frequency of 24 kHz and a nominal power of 400 W at the controlled temperature of 293–298 K for 80 min. In addition, since the cold-water flows in microchannels are placed within the phase change material, so; the cooling water does not allow PCM to melt significantly and lose viscosity. Therefore, the composition of CuO nanoparticles and sheep fat is approximately stable and nanoparticles cannot precipitate.
0
10
20
30
40
50
60
70
80
Time (min) Fig. 3. Variation of the average temperature of the PV module surface without cooling and using PCMs (Q = 6 mL/s).
and the system reached a stable state. The reason for the temperature decrease of the PV module surface in the use of pure paraffin and sheep fat is the absorption of excess heat from its surface by the phase change material. As shown in Fig. 3, the use of sheep fat in comparison with paraffin led to a further decrease in the surface temperature of the PV module and it reached from 77.2 °C to 70 °C. Therefore, it can be concluded that sheep fat is a potential PCM material for the considered passive cooling technique. Regarding general thermal management issues, it is clear that a sheep fat is somewhat better when compared to the conventional PCM material such as paraffin. In addition, according to Fig. 5, it is observed that by adding nanoparticles to sheep fat, the temperature of the PV module surface has decreased and reaches to 63 °C. The presence of copper oxide nanoparticles in the sheep fat as the phase change material leads to an increase in its thermal conductivity and increases the absorption capacity of the heat.
3.2. Effect of water flow rate on the surface temperature of PV module 3. Results and discussion As stated above, in order to postpone the melting of the PCMs, copper tubes in which cold water flows is used. Copper pipes are located with the distance from the module surface and not in contact, and only serves to cool the PCM material in the molten state. Fig. 4 shows the effect of water flow rate (Q) flows in the copper tubes surrounded by PCM on the temperature changes of the PV module surface. In fact, cold water inside the copper tubes is used to exchange heat transfer with PCM. By increasing the surface temperature of the PV module to more than the melting point of PCM, the melting point will begin. Therefore, by flowing cold water into the copper tubes, PCM can be restored to solid state again, and the surface-heat exchange process of the PV module to PCM will continue and change its state. According to the figure, the increase in water flow rate has led to a decrease in the surface temperature of the PV module, which it is owing to preventing of the melting of PCM. In fact, increasing (Q) will increase the heat transfer rate between the water and the PCM around the tubes, and thus improve PCM performance to reduce the surface temperature of the PV module. In addition, in Fig. 4, the comparison between the surface temperatures of the PV module for all three used PCMs shows that in the case of using sheep fat+CuO nanoparticles, the surface temperature of the module is less than the other two, which is consistent with the previous results.
3.1. PV module temperature without cooling and using PCMs Initially, the experiments were performed for the non-cooling system and all data were recorded, including module surface temperature, voltage and current. For the layout of no cooling system, Fig. 3 shows the 9-point temperatures of the PV module surface, as well as the mean of them, over time, to reach a steady state in the absence of a cooling system. According to this figure, the average temperature at the module surface is roughly after 65 min reaches to steady state and the maximum average temperature of the module after 65 min is about 83.3 °C. In the next steps, paraffin, sheep fat and sheep fat+CuO nanoparticles were poured into the reservoir at the backside of the PV module and experiments were repeated to examine the effect of phase change materials on the reducing of the surface temperature of the PV module. In all these steps, the module temperatures were captured as long as the system became stable. Initially, the cold water discharge (Q) was adjusted to 6 mL/s and the amount of 1 kg of each PCM was used to perform the experiments. Fig. 3 shows that with regard to using of pure paraffin and sheep fat and sheep fat +CuO nanoparticles, the surface temperature of the PV module decreased significantly and the slope of the temperature increase was decreased. After 65 min, the surface temperatures of the PV module for the use of all three PCMs were fixed 63
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80 75
Parrafin
24
Sheep fat
22
Sheep fat+CuO
20
70
18 16 14
Voltage (V)
Tsurface (ºC)
65 60
12 10
55
8 6
50
4 2
45
0
40
Without cooling Paraffin Sheep fat Sheep Fat+CuO
0
5
10
15
20
25
30
0
0.05
0.1
0.15
0.2
0.25
35
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
Current (A)
Q (mL/min)
(a) 6
Fig. 4. Effect of water flow rate (Q) on the average temperature of the PV module using PCMs.
Without cooling Paraffin
3.3. Module electrical performance
Sheep Fat+CuO
In order to investigate the effects of phase change material on the generation of electricity by the PV module, its performance without cooling system is first evaluated. Then, I–V data from experiments are collected for three different types of PCMs. V–I experimental data for the standard time range for the without cooling system mode and at the minimum flow rate of the water is shown in Fig. 5 (a). As shown in this figure, the area under the V–I curve increases by using all three types of PCM materials. As the area under the V–I curve shows the power generation of PV module, these results indicate an increase in the output power of the PV module for case of the using sheep fat+CuO nanoparticles compared to pure paraffin and sheep fat. Here, from the V–I values of the studied solar cell in the experiments, it is necessary to define and calculate the generated power from the PV module as follow: The maximum generated power by the PV module (Pmax) can be calculated as follows [16,18]:
PPV = IPV × VPV
Sheep fat
5
Power (w)
4
3
2
1
0
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 Voltage (V)
(b)
(1)
Fig. 5. Output power characteristics curves of PV module for using different PCMs and without cooling layout (Q = 6 mL/s). (a) voltage-current curve, (b) power-voltage curve.
The generated power from the PV module, which works with sheep fat+CuO, is depicted as a function of the output voltage in Fig. 5 (b). As expected, with using each PCM, there is a clear trend in increasing production capacity. The comparison between results of output power obtained for no cooling system and the presence of PCMs could highlight the effect of using phase change materials on the performance of the PV module with water as working cold fluid in better way. In addition, from Fig. 5 (b) it can be conclude that for the layout of using sheep fat as PCM, the PV module achieves higher power output rather than paraffin. According to this figure, the maximum output power is belongs to the PV-sheep fat+CuO system and it is 5.32 watts, which corresponds to a voltage of 14 V. The V–I experimental data and generated power as a function of outlet voltage for the PV module cooled with sheep fat+CuO and Q = 6–31 mL/s is plotted in Fig. 6. As shown in Fig. 6 (a), the area under the V–I curve increases by increase in the flow rate of cold water. Since, the area under the V–I curve is equal to the power generation of PV module, these figure shows an increase in the output power of the PV module for increasing the flow rate of cold water because of increase in postponing the melting time of the sheep fat. As it can be seen in Fig. 6 (b), there is a clear trend of increasing in the generated power from the PV module by increasing the water flow rate. As mentioned above, by increasing Q, the heat transfer rate between the water and the
PCM around the copper tubes increased, and thus leads to improve the PCM performance to reduce the surface temperature of the PV module. In this study, Eq. (2) is used for calculating of increase in the Pmax, which is defined as follow:
PPCM − Pwithout cooling ⎞ P(max) increase = ⎜⎛ ⎟ × 100 Pwithout cooling ⎝ ⎠
(2)
The percentage increase in the electrical PV output for all three PCMs at different water flow rates are presented in Fig. 7. The obtained results for water flow rate (Q) from 6 to 31 (mL/s) shows that by increasing Q, the percentage of maximum power increase, raises remarkably for all of the PCMs. It can be seen that the higher electrical efficiency (26.2%) is obtained with Q = 31 (mL/s) for using sheep fat +CuO nanoparticles, as the lowest average temperature of the PV module occurred in this layout. However, for the pure sheep fat, by increasing the water flow rate, the electrical efficiency has low changes. 4. Conclusions The experimental study has been conducted to investigate the effect 64
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30
24 Q=10 mL/s
20
26
Q=16.5 mL/s
Maximum power increase (%)
Q=26 mL/s
18
Q=31 mL/s
16 Voltage (V)
Q=6 mL/s Q=10 mL/s Q=16.5 mL/s Q=26 mL/s Q=31 mL/s
Q=6 mL/s
22
14 12 10 8 6 4
22
18
14
10
2 0
6 0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 Current (A)
2
(a) 7
Q=10 mL/s
Nomenclatures
Q=26 mL/s
Power (w)
Sheep fat+CuO
Q=16.5 mL/s
5
Q=31 mL/s
I IPV Pmax PPCM PPV Pwithout TPCM VPV
4
3
2
1
0
Sheep fat
Fig. 7. % Maximum power increase for the PV module at the different water flow rate for different PCMs.
Q=6 mL/s
6
Paraffin
Average intensity on absorber plate (W/m2) Photovoltaic arrays current (A) Maximum power of photovoltaic arrays (W) Power of photovoltaic arrays by cooling with PCM (W) Photovoltaic arrays power (W) cooling Reference power (W) Temperature of photovoltaic arrays by using PCM (°C) Photovoltaic arrays voltage (v)
Subscripts max 0
1
2
3
4
5
6
7
8
Maximum
9 10 11 12 13 14 15 16 17 18 19 20 21 22 Voltage (V)
Abbreviations
(b)
PV
Fig. 6. Effect of water flow rate on the Output power characteristics curves for sheep fat+ CuO suspension. (a) voltage-current curve, (b) power-voltage curve.
Photovoltaic
References
of using a novel phase change material (PCM) on the cooling performance of a PV module. Firstly, the surface average temperature of PV cell without cooling system as a reference system has been recorded based on time to reach the surface temperature at steady condition. Secondly, the effects of using paraffin wax and sheep fat as PCMs have been experimentally evaluated. The sheep fat has been used as a novel PCM and in order to increase its cooling efficiency, CuO nanoparticles (0.004 (w/v)) have been added to the sheep fat. The effect of using sheep fat+CuO nanoparticels for decrease in the surface average temperature of the PV module, power generated and electrical outputs of the systems as the critical parameters have been compared with the case of paraffin wax and pure sheep fat. Results depicted that using both PCMs has high capability for improving the cooling performance of the studied the PV module. Moreover, results show that using sheep fat +CuO nanoparticels significantly decreased the average temperature of the PV module surface compared to the cases of not cooling system and using pure sheep fat. Simultaneous use of PCM and CuO nanoparticles lead to increase in the percentage of maximum power increase from 24.6–26.2% related to flow rate of water flowing in microchannel tubes.
[1] N. Heidari, M. Rahimi, N. Azimi, Experimental investigation on using ferrofluid and rotating magnetic field (RMF) for cooling enhancement in a photovoltaic cell, Int. Commun. Heat Mass Transf. 94 (2018) 32–38. [2] M. Ebrahimi, M. Rahimi, A. Rahimi, An experimental study on using natural vaporization for cooling of a photovoltaic solar cell, Int. Commun. Heat Mass Transf. 65 (2015) 22–30. [3] S.S. Chandel, Tanya Agarwal, Review of cooling techniques using phase change materials for enhancing efficiency of photovoltaic power systems, Renew. Sust. Energ. Rev. 73 (2017) 1342–1351. [4] C.G. Popovici, S.V. Hudișteanu, T.D. Mateescu, N.C. Cherecheș, Efficiency improvement of photovoltaic panels by using air cooled heat sinks, Energy Procedia 85 (2016) 425–432. [5] M. Emam, S. Ookawara, M. Ahmed, Performance study and analysis of an inclined concentrated photovoltaic-phase change material system, Sol. Energy 150 (2017) 229–245. [6] M. Sardarabadi, M. Passandideh-Fard, S. Zeinali Heris, Experimental investigation of the effects of silica/water nanofluid on PV/T (photovoltaic thermal units), Energy 66 (2014) 264–272. [7] M. Ghadiri, M. Sardarabadi, M. Pasandideh-fard, A.J. Moghadam, Experimental investigation of a PVT system performance using nano Ferrofluids, Energy Convers. Manag. 103 (2015) 468–476. [8] S.A. Kalogirou, Y. Tripanagnostopoulos, Hybrid PV/T solar systems for domestic hot water and electricity production, Energy Convers. Manag. 47 (2006) 3368–3382. [9] Y. Su, Y. Zhang, L. Shu, Experimental study of using phase change material cooling in a solar tracking concentrated photovoltaic-thermal system, Sol. Energy 159 (2018) 777–785. [10] S. Preet, B. Bhushan, T. Mahajan, Experimental investigation of water based
65
International Communications in Heat and Mass Transfer 100 (2019) 60–66
L. Siahkamari et al.
[11]
[12] [13] [14]
[15] [16] [17] [18]
[19]
[20]
photovoltaic/thermal (PV/T) system with and without phase change material (PCM), Sol. Energy 155 (2017) 1104–1120. J. Barrau, J. Rosell, D. Chemisana, L. Tadrist, M. Ibaoez, Effect of a hybrid jet impingement/micro-channel cooling device on the performance of densely packed PV modules under high concentration, Sol. Energy 85 (2011) 2655–2665. M. Rahimi, E. Karimi, M. Asadi, P.V. Sheyda, Heat transfer augmentation in a hybrid microchannel solar cell, Int. Commun. Heat Mass Transf. 43 (2013) 131–137. R. Stropnik, U. Stritih, Increasing the efficiency of PV panel with the use of PCM, Renew. Energy 97 (2016) 671–679. M. Sardarabadi, M. Hosseinzadeh, A. Kazemian, M. Passandideh-Fard, Experimental investigation of the effects of using metal-oxides/water nanofluids on a photovoltaic thermal system (PVT) from energy and exergy viewpoints, Energy 138 (2017) 682–695. S. Dong, T.M. Shih, W. Lin, X. Cai, R.R.G. Chang, Z. Chen, Time-dependent photovoltaic-thermoelectric hybrid systems, Numer. Heat Transf. A 66 (2014) 402–419. N. Karami, M. Rahimi, Heat transfer enhancement in a PV module using Boehmite nanofluid, Energy Convers. Manag. 86 (2014) 275–285. S. Agrawal, A. Tiwari, A, Experimental validation of glazed hybrid micro-channel solar cell thermal tile, Sol. Energy 85 (2011) 3046–3056. N. Karami, M. Rahimi, Heat transfer enhancement in a hybrid microchannel-photovoltaic module using Boehmite nanofluid, Int. Commun. Heat Mass Transf. 55 (2014) 45–52. S. Nižetić, M. Arıcı, F. Bilgin, F. Grubišić-Čabo, Investigation of pork fat as potential novel phase change material for passive cooling applications in photovoltaics, J. Clean. Prod. 170 (2017) 1006–1016. M.J. Hosseini, A.A. Ranjbar, K. Sedighi, M. Rahimi, A combined experimental and computational study on the melting behavior of a medium temperature phase
[21]
[22]
[23]
[24] [25]
[26]
[27]
[28]
66
change storage material inside shell and tube heat exchanger, Int. Commun. Heat Mass Transf. 39 (2012) 1416–1424. A.H.A. Al-Waeli, K. Sopian, M.T. Chaichan, H.A. Kazem, A. Ibrahim, S. Mat, M.H. Ruslan, Evaluation of the nanofluid and nano-PCM based photovoltaic thermal (PVT) system: an experimental study, Energy Convers. Manag. 151 (2017) 693–708. M.J. Huang, P.C. Eames, B. Norton, Thermal regulation of building-integrated photovoltaics using phase change materials, Int. J. Heat Mass Transf. 47 (2004) 2715–2733. K. Karunamurthy, K. Murugumohankumar, S. Suresh, Use of CuO nanomaterial for the improvement of thermal conductivity and performance of low temperature energy storage system of solar pond, Digest J. Nanomater. Biostruct. 7 (2012) 1833–1841. P.H. Biwole, P. Eclache, F. Kuznik, Phase-change materials to improve solar panel's performance, Energ. Build. 62 (2013) 59–67. D. Su, Y. Jia, Y. Lin, G. Fang, Maximizing the energy output of a photovoltaic–thermal solar collector incorporating phase change materials, Energ. Build. 153 (2017) 382–391. M. Sardarabadi, M. Passandideh-Fard, M.J. Maghrebi, M. Ghazikhani, Experimental study of using both ZnO/water nanofluid and phase change material (PCM) in photovoltaic thermal systems, Sol. Energy Mater. Sol. Cells 161 (2017) 62–69. S. Mousavi, A. Kasaeian, M.B. Shafii, M.H. Jahangir, Numerical investigation of the effects of a copper foam filled with phase change materials in a water-cooled photovoltaic/thermal system, Energy Convers. Manag. 163 (2018) 187–195. S. Preet, Water and phase change material based photovoltaic thermal management systems: a review, Renew. Sust. Energ. Rev. 82 (2018) 791–807.