Lead Performer: University of Wisconsin – Madison, WI
Partners:
-- National Renewable Energy Laboratory – Golden, CO
-- Purdue University – West Lafayette, IN
-- Texas A&M Engineering Experiment Station – College Station, TX
-- NETenergy – Chicago, IL
-- Daikin Comfort Technologies North America – Plymouth, MN
DOE Total Funding: $2,498,973
Cost Share: $627,204
Project Term: January 1, 2024 – December 31, 2026
Funding Type: Buildings Energy Efficiency Frontiers & Innovation Technologies (BENEFIT) – 2022/23
Project Objective
University of Wisconsin and its partners will develop a flexible plug-and-play vapor compression system platform that allows direct integration of modular thermal energy storage (TES) units to air source heat pumps. The goal of this system is to help electrify buildings while providing a storage resource to the grid. The system will build upon a standard multi-split system, in which the TES can replace ambient air as the alternative heat source/sink during discharge to reduce electric power consumption by 40-50% for up to four hours in both the summer and winter when compared to a direct-expansion heat pump without TES. Additionally, this TES system can easily be integrated with existing variable refrigerant flow systems designed for concurrent heating and cooling; bolster energy efficiency through improved heat transfer between the refrigerant and storage medium (in this case, a phase change material, or PCM) via direct thermal contact; and provide extra benefits like using the PCM for defrosting, which mitigates the need for backup heating systems.
This project will analyze and demonstrate the addition of thermal storage in a commercially available HVAC system. In the project, the team will:
- Further develop inexpensive salt-hydrate PCMs (<$15/kWh) at appropriate transition temperatures for this system
- Design modular TES evaporators and condensers with >95% utilization
- Develop a plug-and-play controller
- Demonstrate >40% peak demand reduction for up to four hours
The team will also develop a social and environmental net benefit screening tool to help support equitable and beneficial commercialization efforts.
Project Impact
This work will result in the demonstration of a heat pump with integrated thermal storage. The focus of the project will be to reduce the upfront cost of the TES unit to under $40/kWh at scale. We will lower barriers to adoption by using low-cost high energy density PCMs to reduce the size of TES modules, and lower installation costs through the use of quick-connect fittings. In all, the result will be an affordable and flexible HVAC system that helps prepare buildings to meet the 2050 U.S. climate goals in equitable ways.
Contacts
DOE Technology Manager: Sven Mumme
Lead Performer: Allison Mahvi, University of Wisconsin - Madison