Thermoeconomic optimization of a sensible-heat thermal-energy-storage system: A complete storage cycle

An analytical model for the second-law-based thermoeconomic analysis and op timization of a sensible-heat-storage system is derived and discussed, in w hich the storage Element is both heated and cooled by flowing streams of ga ses. In this analysis, monetary values are attached to the irreversible los ses caused by the finite temperature difference heat transfer and pressure drop in the storage system. Important dimensionless parameters are identifi ed and the results are presented in terms of the optimum dimensionless char ging time theta(S,opt) as a function of a dimensionless temperature differe nce tau, as well as the optimum number of heat transfer units NTUS,opt as a function of the dimensionless unit cost per unit heat conductance gamma(UA ) and tau Of the storage systems. The systems analyzed are optimized by int roducing a new performance criterion described as the cost rate number, Gam ma*. Several example problems are also presented and the results are compar ed with that obtained from Krane's analysis to illustrate the usefulness of the present approach. The influence of important unit cost parameters on N TUS,opt and theta(S,opt) are also studied in somewhat more detail.