Analysis of Building Cooling System's Load Under the Effect of the Phase Change Material-Based Thermal Energy Storage System

Phase change material (PCM) based cooling load reduction analysis commonly incorporates thermal energy storage (TES) on the building interior. Such systems are constrained by the limited overlap in suitable exterior temperatures for TES recharging with acceptable indoor comfort temperatures. In the current paper, this constraint is removed by moving the TES to the exterior and optimizing the TES system design for a certain climate, including PCM size and operating temperature window. The goal of this optimization will be reducing the ambient air temperature before the condensing heat exchanger in typical HVAC equipment for cooling applications to improve its coefficient of performance (COP) and minimize the annual cost. Utilization of organic fatty acid mixtures as the PCM will allow for selecting a solidification temperature appropriate to a given climate. This analysis attempts to minimize the annual cost of cooling structures by appropriately sizing TES systems with suitable eutectic or near-eutectic mixtures of fatty acids for a given climate. For a targeted climate, by analyzing the solidification temperature of a fatty acid mixture and the temperature at which the TES cools the ambient air, energy usage is reduced at times of peak cooling demands to optimize the efficiency of the combined TES and HVAC system and maximize energy cost savings.