Exergy maximization in refrigeration storage units with heat leak

Abstract

This Paper presents Second Law of Thermodynamics analysis techniques for sensible refrigeration energy storage units with non-adiabatic boundaries. The investigation is based on the minimization of entropy production due to a finite temperature difference. The results of this study indicate three basic points: 1, in the presence of heat leaks, the irreversibility rate is more than in its absence; 2, the increase in irreversibility due to heat leaks reduces the effective N(sub)tu exponentially; 3, there exists a dimensionless optimum time parameter which relates two other fundamental dimensionless parameters for the maximization of useful work stored. These fundamental parameters are N(sub)tu associated with heat flow across the non-adiabatic wall and N(sub)tu of the storage unit. These points suggest that the leakage heat affects the entropy production adversely and hence it should be kept at a minimum.