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

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$1,290,091

Amount Spent

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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

Develop, test, and demonstrate a lower cost high-efficiency heat pump utilizing a low-GWP (<750) refrigerant.
Develop and test a high-efficiency microchannel heat exchanger with 15 to 20 percent higher effectiveness than standard.

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

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.

Lower Costs

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 & Public Health

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

Vinod Narayanan

Principal Investigator
UC Davis WCEC
Curtis Harrington

Curtis Harrington

Co-Director of Engineering
UC Davis WCEC
Felix Villanueva

Felix Villanueva

Commission Agreement Manager/Utility Engineer
California Energy Commission

Subrecipients

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TRC Engineers, Inc.

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Rheem

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Merced County Community Action Agency

Match Partners

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Southern California Edison

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Regents of the University of California, Davis

Contact the Team

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