Affordable Near- and Medium-Term Solutions for Integration of Low GWP Heat Pumps in Residential Buildings
Develop and Demonstrate next generation heat pumps utilizing low global warming potential refrigerant, achieve high efficiency, and achieve cost savings.
The Regents of the University of California, on behalf of the Davis Campus
Recipient
Davis, CA
Recipient Location
3rd
Senate District
4th
Assembly District
$1,290,091
Amount Spent
Active
Project Status
Project Update
The project completed retrofitting ten demonstration sites with the near-term heat pump solution which uses a lower-cost compressor drive coupled with the low-GWP refrigerant, R-454B. The existing systems were monitored for one year to establish the baseline energy usage for each home followed by a year of post retrofit monitoring. The medium-term solution was focused on improving the performance of air-to-water heat pumps with the potential of safely incorporating ultra-low GWP, natural refrigerants. This project developed advanced microchannel polymer heat exchanger designs to improve heat exchanger performance relative to typical fin-tube type heat exchangers used in hydronic systems. The project team evaluated different manufacturing methods for developing the polymer heat exchanger such as injection molding and 3D printing. A commercial-scale 1.5 Ton heat exchanger was tested in the laboratory and used to validate heat exchanger models for further improving the design. The optimized design showed a 15-20% improvement in heat transfer effectiveness compared to the standard fin-tube design.
The Issue
Next generation heat pump technologies have the potential to significantly reduce greenhouse gas emissions from buildings in California but have had some challenges penetrating the California marketplace, largely due to high initial costs. In order to meet California's aggressive energy and carbon goals it will be necessary to find low-cost solutions for switching the primary fuel for heating buildings from natural gas to electricity while also improving the heating and cooling efficiency of heat pumps.
Project Innovation
This project developed and demonstrated affordable near-term (TRL 4- high 7) and medium-term (TRL 4- low 7) solutions for integration of lower cost, low- and ultra-low global warming potential (GWP) heat pumps. The combination of addressing both near-term (GWP <750) and medium-term (ultra-low GWP <10) needs is necessary to meet California's carbon reduction goals. The near-term solution focused on a closer-to-market emerging technology that uses a proprietary, a lower cost compressor drive. This technology was demonstrated for cost and energy savings at 10 pilot sites. The project found that while the near-term heat pump reduced energy use and greenhouse gas emissions compared to the baseline systems, there were still operating cost increases on the participants due to the relative cost of natural gas compared to electricity. The novel design did reduce equipment cost by 20-25% compared to similarly efficient heat pump technologies on the market. The medium-term solution incorporated an innovative heat exchanger in the secondary loop to improve air-to-water heat pump efficiency, enabling use of hermetically-sealed ultra-low GWP flammable refrigerants in heat pumps. This technology was validated in the laboratory and shows promise in commercial applications. The project team will continue to pursue commercialization of the heat exchanger design by developing practical and cost-effective manufacturing methods for the product.
Project Goals
Project Benefits
This project advances high-efficiency heat pump equipment at a lower installed cost compared to current competing heat pump technology, improving the appeal and affordability of heat pumps. Heat pumps are vitally important in the effort to meet California's carbon reduction goals through building electrification, but until now their cost has hindered widespread adoption.
Consumer Appeal
Reducing the cost of heat pumps will make them more attractive to customers who have so far largely ignored them due to high upfront costs relative to alternatives.
Affordability
The proposed research will lead to lower costs for heat pumps in the near- and medium-term. This is necessary for greater market uptake.
Environmental Sustainability
A total of 9.2 Million therms of natural gas could be offset through increased use of electric heat pumps, and while this would increase the electric demand statewide by 63.7 GWh, the greenhouse gas emissions in California would decrease due to the fuel switching.
Key Project Members
Vinod Narayanan
Curtis Harrington
Felix Villanueva
Subrecipients
TRC Engineers, Inc.
Rheem
Merced County Community Action Agency
Match Partners
Southern California Edison
Regents of the University of California, Davis
