Exergy Analysis of Adsorption Cooling Systems Based on Numerical Simulation

Adsorption cooling system is driven by low-grade heat sources and is an eco-friendly system, is therefore considered a potential alternative to the traditional vapor-compression refrigeration system. An exergy analysis is a tool for identifying the details of energy degradation of each process and component, but there is a critical limitation in previous works which assumed there was no spatial variation in the adsorption beds, i. e., the lumped capacity method. We have conducted both an energy and exergy analysis of an adsorption cooling system. The exergy analysis was conducted based on detailed information obtained from the CFD results of energy analysis. The numerical results provide detailed information which varies in time and space, free of the assumptions used in lumped capacity methods, by including the effects of geometric features (fin height, fin spacing, tube diameter, and thickness) and, the contact resistance between sorbent material and metallic finned tube, which affirmatively enhance the accuracy of the exergy analysis. Finally, we analyze the effect of several main parameters from the view point of the 2nd law of thermodynamics. The results show that increases in the temperature of the heat sources leads to an increase in energy performance while the exergy efficiency decreases; increases in the cooling water temperature reduces the COP, SCP, and eta(ex). An increase in cycle time improves the COP and eta(ex) but reduces the SCP.