Exergy Analysis of Adsorption Cooling Systems Based on Numerical Simulation

Abstract

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 ηex. An increase in cycle time improves the COP and ηex but reduces the SCP.

Exergy Analysis of Advanced Adsorption Cooling Cycles

“…Therefore, the exergy efficiency of the basic cycle is the lowest, at 0.1013, compared to the other advanced cycles. This is in good agreement with our previous findings [ 20 ].…”

“…The parameter values and typical operating conditions are shown in Table 1 . The details of the assumptions, governing equations, boundary conditions, numerical approach and their validation are available in our previous work [ 12 , 20 , 22 ]. Thus, this study shortly describes the necessary hypotheses and governing equations for the mathematical model.…”

“…The primary aim of an exergy analysis is to provide the causes and true magnitudes of exergy losses [ 16 ]. Until now, exergy analyses have mainly been conducted to investigate the basic adsorption cooling cycle [ 17 , 18 , 19 , 20 ], and rarely for advanced cycles. Moreover, the existing exergy analyses of advanced cycles have been based on the rough lumped model.…”

“…However, there has been no study on the exergy analysis of the advanced cycles, especially based on a rigorous analysis of the sorption bed. Note that our recent research on the basic cycle showed that the rigorous results of the CFD model in sorption beds were different from those of the conventional lumped model, by approximately 15.95%, 73.8%, and 16.33% of the COP, SCP and exergy efficiency, respectively [ 20 ].…”

Optimization and Analysis of Minimizing Exergy Loss in Ironmaking System

“…Li et al [ 28 ] held that exergy analysis could better reveal the energy efficiency of the system by providing more detailed internal information. At present, the exergy analysis has been widely applied in many sectors such as thermal engineering, [ 25,29–31 ] chemical engineering, [ 32–36 ] environment, [ 37–39 ] economics, [ 40–43 ] and so on.…”