A comparative study on PCM and ice thermal energy storage tank for air-conditioning systems in office buildings

Significant increasing demand of air conditioning (A/C) systems has led to more power consumption during on-peak hours in recent years. In this paper, a vapor compression A/C system has been analyzed via two strategies of hybrid systems. First, an ice thermal energy storage (ITES) system is used in the a.m. hybrid system; and thereafter a phase change material (PCM) tank is used as a full storage system (in order) to shift (the load) from on-peak to off-peak mode. This A/C system is modeled and analyzed from exergetic, economic and environmental point of views for both cases; then, using non-dominated sorting genetic algorithm-II (NSGA-II), multi-objective optimization is carried out and the optimal values of decision parameters are achieved. The exergy efficiency and total cost rate are considered as objective functions, and then ITES, PCM and conventional systems are compared. The results have illustrated that the power consumption of ITES and PCM systems are 4.59% and 7.58% lower than the conventional system respectively. Moreover, CO2 emission production for ITES and PCM systems are 17.8% and 27.2% lower than conventional system respectively. (C) 2016 Published by Elsevier Ltd.