Design of a chilled-water storage unit for solar air-conditioning

Solar powered air-conditioning requires some form of thermal energy storage in order to continuously balance energy supply and demand. The current paper is concerned with energy storage in the form of stored chilled water produced by a chiller during times when supply is more than demand. A new multi-tank storage unit design is presented and evaluated employing a specially developed mathematical model and computational code that predicts the various modes of heat transfer occurring within the storage unit. The computational code is both efficient and accurate; it is presented and employed to investigate the effect of various operating parameters and design options on performance. It is revealed that employing only modest insulation, the daily heat penetration is around 2% of the daily stored cooling-capacity. This loss is much lower than the losses involved in other forms of energy storage, such as battery storage, and expected to be cheaper and more environmentally friendly.