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Abstract
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Electricity generated by photovoltaic (PV) modules can be converted into cooling using well-known refrigeration technologies based on vapor compression refrigeration cycles. One of the most critical issues arising when using PV modules is elevated temperatures in sunny and hot conditions, resulting in a corresponding decrease in electrical efficiency. Therefore, this work aims to enhance the performance of a solar compression refrigeration system using a single PV-thermal (PVT) collector fully integrated with a refrigeration system employing a low GWP refrigerant (R290) instead of the R134a. Furthermore, zinc oxide (ZnO) nanofluid is used to absorb thermal energy from the PVT collector and to improve its electrical efficiency. The outlet fluid from the PVT collector is used to subcool the refrigerant at the outlet from the condenser of the cycle. The impacts of varying the nanofluid flow rate, nanoparticle concentration, evaporator, and condenser temperatures on the performance of the system are thermodynamically evaluated. The theoretical analysis based on the first and second laws of thermodynamics indicates that using ZnO nanoparticles enables an enhanced Solar Cooling Efficiency (SCE) and Coefficient of Performance of the system by more than 30%, from 21 to 28% and from 9 to 12%, respectively, for various nanoparticle concentrations ranging from 0 to 6%. The use of the nanofluid results in a 1–6% decrease in the total heat exchanger area compared to pure water in the solar-collector circuit. Finally, it is reported that using R290 enhances the SCE by 3%, compared to a system employing R134a as the refrigerant.
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