Modeling peak load reduction and energy consumption enabled by an integrated thermal energy and water storage system for residential air conditioning systems in Austin, Texas

Abstract

This paper discusses the development of a model for evaluating peak load reduction and change in overall energy consumption for a residential air conditioning (AC) compressor with and without condenser-side thermal storage. Stored rainwater (or any other type of on-site water storage) could be utilized as a heat sink for the condenser during peak hours, allowing for more efficient and lower power compressor operation, then re-chilled at night during off-peak hours. The system evaluated in this manuscript is referred to as ‘integrated thermal energy and rainwater storage’ (ITHERST).The model used simulated cooling load data for a typical home in Austin, Texas, based on summer 2011 historical and typical meteorological year (TMY) datasets. The analysis suggests that the ITHERST system with 3785–18,925l of water could reduce on-peak compressor power demand by approximately 29–53%, as compared to a traditional AC with an air-cooled condenser. However, total compressor energy consumption increases 5–15% because of the inefficiencies of re-cooling the thermal mass, but this additional energy consumption occurs during low demand off-peak hours. System performance varied depending on weather data, the individual compressor, and thermal storage volume.