Energy and Exergy Analysis of Nanofluid Based Solar Assisted Power Generation and Absorption Cooling Systems

The present study is conducted to perform the comparative analysis of solar assisted multi-effect absorption cooling systems. Absorption cooling cycles, from single to quadruple effects are analyzed for their energy and exergy perspectives. In the first half of the analysis, the solar collectors (parabolic trough and parabolic dish) are modelled and analyzed using water based nanofluids of Al2O3 and Fe2O3. Secondly, the absorption cooling cycles of single, double, triple and quadruple effects are simulated and analyzed separately. Then finally, they are integrated with solar collectors to produce power as well as to provide heating and cooling effect. All the four absorption cycles are designed to work on LiBr-H2O working pair and are analyzed for their coefficient of performance (COP) as well as exergetic performance viewpoints. The absorption cycles are operated on a heat source of solar energy collected through solar collectors. It is observed that the quadruple effect absorption cycle (QEAC) has substantial performance enhancement over the double and triple effect absorption cycles. The QEAC consists of four generators and four condensers coupled together, making an extension of triple effect absorption cycle where there are three condensers and three generators joined together to complete the cycle. The system is designed to work on parallel flow system. All four absorption cycles are designed to have the identical cooling output and same operating conditions. Engineering Equation Solver (EES) software is used to simulate and study the effects of various operational aspects on the COP and exergetic performance of the cycles. The triple effect absorption cycle is observed to have COP of more than twice the single effect and for quadruple it is 2.55 times higher than single effect absorption cycle. The exergetic efficiency of the quadruple absorption effect cycle is 11.7% higher than single effect and 6% higher than triple effect absorption cycle. It is found that for a fixed evaporator temperature and for a fixed condenser load, there is an optimal temperature of the generator, where the COP and exergy efficiency are found to be maximum. A small modification of mass distribution among the generators would help in higher COP without requiring any additional heat input. Quadruple effect absorption cycle works on higher heat source temperatures in comparison to single effect absorption cycle but requires less heat input to produce the same cooling effect.