Session: 04-01: Energy Storage Systems and Applications

Paper Number: 169563

169563 - Flattening Utility Demand Through a Low-Cost, Phase-Change-Material Thermal Energy Storage System Design 

Abstract: 

Deep decarbonization and intermittent renewable electricity supply require widespread adoption of energy storage technologies including building-sited thermal energy storage (TES). In order to effectively scale up the impact of these systems, they must be low-cost with high energy-storage density. Latent TES systems rely on phase change materials (PCM) as the storage medium which allows for high storage density over relatively small temperature ranges. The PCM must be encapsulated in some manner and one such method employs a tube bank in crossflow with the cooling system’s airstream. The tube bank design is generally well-studied and widely implemented in other applications, making its application straightforward and cost-effective. This experimental investigation uses a bio-based PCM to flatten utility demand associated with building cooling. The small-scale system uses tube-bank encapsulation to both isolate the PCM and provide sufficient surface area to maximize the heat transfer rate to and from the storage medium. The system consists of staggered thin-walled copper tubes mounted the duct of a mini-split air-conditioning system. Cool air is delivered at 11°C to freeze the PCM with a phase transition temperature of 15°C. During periods of peak utility demand, room air around 22°C is circulated past the tube bank to deliver cool air without running the mini-split’s compressor. The scaled-down, inexpensive thermal storage system provides significant shifting of electricity demand. Scaling the system up to capacities appropriate for large building cooling systems in addition to widespread adoption could serve to significantly flatten utility system demand especially during peak cooling periods.

Presenting Author: Amy Van Asselt Lafayette College

Presenting Author Biography: Amy Van Asselt is an Assistant Professor at Lafayette College in Easton, Pennsylvania. She obtained her BS at University of Illinois, her MS at University of Washington, and her PhD at University of Wisconsin, all in Mechanical Engineering. Her research area of focus is in building-sited thermal energy storage systems to serve the electric grid.