Ice thermal storage, demand response, residential cooling system
In recent years, variable electricity pricing has become available to residential consumers to incentivize demand reductions during traditional midday peak hours. This is especially important in hot climates where air-conditioning (A/C) use is the primary cause for peak electricity demand. Thermal storage allows consumers to store “cooling” when demand is low and minimize operation of the A/C during peak periods. This paper considers a packaged A/C integrated with thermal energy storage using ice for residential cooling applications. The focus of the paper is the development and validation of a generalized control strategy that can be used for available residential utility rate structures that include different combinations of time-of-use energy and demand charges. The generalized control strategy is based on a unique combination of different heuristic strategies for charging and discharging of storage that are typically applied to commercial-scale A/C systems with integrated thermal energy storage. In order to evaluate overall performance, a model of the proposed system is developed and used to calculate cooling season operating costs for different geographic locations and utility rates. The performance of the generalized strategy is evaluated in comparison to the most commonly employed control strategy for commercial ice storage systems, called chiller priority control. A range of unit capacities, storage sizes, geographic locations, and residential utility rates are considered. The resulting decrease in operating cost with the generalized control strategy, when compared to chiller priority control, was as much as 50% based on the utility rates considered in this paper.