Modeling and simulation analysis of solar absorption chiller driven by nanofluid-based parabolic trough collectors (PTC) under hot climatic conditions

Abstract

The performance of solar air conditioning system (SACS) using Lithium-Bromide/water (Li–Br/H2O) solution and nanofluid -based parabolic trough collectors (PTC) under hot and humid climate conditions is presented in this study. The main objectives are to investigate the effects of different types of nanofluid (Al2O3/H2O and Cu/H2O) and the concentration of nanoparticle Cu (0.2 and 0.5 wt %) on the coefficient of performance (COP) of SACS system during a winter and summer days in desert regions. Mathematical models of the SACS system including the solar PTC, tank storage and the single-effect Li–Br/H2O absorption chiller are developed. The numerical simulation results show a good agreement with the experiment data accessible in literature. The results show that Cu/H2O nanofluid has the best performance. For the cold day and at noontime, the COP for pure water, 0.5 vol% Al2O3/H2O nanofluid and 0.5 vol% Cu/H2O nanofluid are 0.64, 0.68, and 0.74, respectively. The COP during the cold day increases by 12.5% and 15.5% when the concentration of Cu nanoparticle is 0.2 %vol and 0.5 %vol respectively. For the hot day and between 9:00 a.m. to 3:00 p.m. the maximum COP obtained is 0.77, and the effect of nanofluids is negligible. The single LiBr–H2O air absorption system reaches its maximum operation. A double effect of LiBr–H2O air absorption is needed to improve the performance of the system.