Integrated Thermal Energy Storage System for Air-Conditioners with Phase-Change Composites

Conference · Fri Aug 13 04:00:00 EDT 2021

OSTI ID:1860477

Goyal, Anurag; Kozubal, Eric; Woods, Jason

Thermal energy storage (TES) is a promising solution to store and dispatch energy and shave peak electric load, reducing the operational cost of HVAC systems. We present results of a TES system using phase-change materials (PCM) integrated with an air conditioner. The proposed system uses an organic PCM (tetradecane) encapsulated within compressed expanded natural graphite foams referred to as phase-change composite. The graphite foam encapsulates the PCM eliminating the need for expensive storage vessels, reduces installation costs, and provides higher thermal conductivity that can lead to faster charge/discharge rates. Two serpentines, multi-pass circuits, operating as a heat source and a sink, exchange heat to and from the phase-change composite. These two circuits are embedded in multiple slabs of this material. The "charge" circuit contains the refrigerant that is directly coupled to a vapor compression system, and the "discharge" circuit removes heat from an airstream and releases it into the PCM composite through a water-glycol liquid coupling. This configuration allows for multiple modes of operation depending on the state of charge of the thermal energy storage module, the building air-conditioning load, and the current electricity and demand charges. This flexible operation allows variable air volume capacity control without the need to have a variable capacity refrigeration system. We developed a 21 kW-hr (6 RT-hr) prototype TES system coupled with a commercial air-conditioner to characterize the component-and system-level performance.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1860477
• Report Number(s): NREL/CP-5500-79605; MainId:35826; UUID:ca5f91f5-f23d-44cb-90d0-d21bf5191dc9; MainAdminID:64134
• Country of Publication: United States
• Language: English

Related Subjects

ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
air-conditioning
building energy efficiency
buildings
composite phase-change material
system integration
thermal energy storage