Keywords: solar cooling systems, lithium bromide, exergy analysis, numerical simulation, energy analysis, absorption cooling, solar energy, solar power, coefficient of performance, COP, exergy destruction, irreversibility
Energy and exergy analyses of a solar–driven absorption cooling system
In this paper, energy and exergy analyses of an absorption cooling system using H2O/LiBr and solar energy as heat source are conducted. A simple schematic of a chiller and an improved one, are compared using Thermoptim and EES software. An increase in the coefficient of performance (COP) from 0.69 to 0.8 was noticed. Numerical simulations are performed for six values of the condensing/absorption temperatures, which vary in the interval 31–36°C. The increase in these temperatures implies a decrease in the COP from 0.8 to 0.56. The exergy analysis of the overall system and of each component shows a decrease in the exergetic efficiency of the system from 0.27 to 0.18. A detailed exergy analysis of the absorber reveals the real causes of exergy destruction. A new exergy destruction indicator was introduced, which shows the importance of the irreversibility of each component, relative to the starting potential.