Determining the performance characteristics of flat plate and photovoltaic thermal collector for sustainable cooling systems integration

Improvement of the overall performance of solar cooling systems is achievable by optimising inlet conditions for the highest thermal efficiency of solar collectors such as flat plate collectors (FPC) and photovoltaic thermal collectors (PVT). This study has highlighted the recent advances in the field of solar absorption cooling systems from the point of view of the solar collector's types and has conducted an extensive review of the use of FPC and PVT for absorption cooling systems. The aim of this study is to investigate and optimise the thermal efficiency of FPC and PVT for sustainable cooling systems. The effect of inlet temperature (Tin) and flowrate (m ) on thermal efficiency (η_th) of FPC was investigated. Computational Fluid Dynamics (CFD) was employed to simulate a FPC and the results validated with experimental data from literature. Increasing inlet water temperature of FPC from 298 K to 370 K reduced thermal efficiency by 30%. There was no significant impact when the total flowrate of FPCs exceeded 36.4 x10-3 kg/s/m2. CFD was also employed to simulate a PVT and was validated by the literature. The effect of Tin and m on thermal efficiency(η_th) and electrical efficiency (η_elc) for the PVT was investigated. Increasing inlet water temperature of PVT from 273 K to 373 K reduced thermal efficiency by 7% while there was a significant reduction in electrical efficiency by 45% due to the increase in photovoltaic layer temperature. There was no significant impact when the total flowrate of the PVT exceeded 35 x10-3 kg/s/m2. The inlet conditions of FPC and PVT were optimised for the highest efficiency in accordance with the minimum absorption cooling driving temperature currently available in the market. A multi-objective optimisation study was applied to the computational model of the FPC by employing the response surface optimisation method in ANSYS16.1. The optimum flowrate of the FPC was m =0.0067 kg/s/m2 with an inlet temperature of 321 K for thermal efficiency of 84 %. A multi-objective optimisation study was also applied to the computational PVT model. The optimum flowrate of the PVT was m =0.0165 kg/s/m2 with an inlet temperature of 337.36 K for thermal and electrical efficiency of 81.32 % and 11.26 % respectively. The study has managed to optimise inlet conditions for FPC and PVT coupled with a cooling system at specified conditions. Optimising the inlet conditions has a significant impact to increase solar coefficient of performance (SCOP).