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Progress in Ground-source Heat Pumps Using Natural Refrigerants
Wei Wu1, Harrison M Skye1, Lingnan Lin1
1National Institute of Standards and Technology, Engineering Laboratory, Energy and Environment Division, HVAC&R Equipment Performance Group, USA.
Revue Internationale Du Froid
|July 6, 2019
Summary
Natural refrigerants like CO2, ammonia, and propane offer sustainable alternatives for ground-source heat pumps (GSHPs). This review details their properties and performance, aiding the transition from high-GWP fluorinated refrigerants.
Area of Science:
- Sustainable energy technologies
- Thermodynamics and fluid dynamics
Background:
- Fluorinated refrigerants in ground-source heat pumps (GSHPs) pose environmental risks due to high Global-Warming Potential (GWP).
- Natural refrigerants present a viable, eco-friendly alternative for GSHP systems.
Purpose of the Study:
- To conduct a comprehensive survey of natural refrigerants used in GSHPs.
- To compare thermodynamic properties and analyze performance of various natural refrigerants in GSHPs.
Main Methods:
- Literature review and comparative analysis of studies on CO2, NH3, water, and hydrocarbons in GSHPs.
- Evaluation of refrigerant performance in brine-to-air and brine-to-water configurations.
Main Results:
- CO2 is the most studied natural refrigerant, with applications in advanced, direct-expansion, secondary fluid, and hybrid GSHPs.
- Ammonia (NH3) is the second most studied, used in vapor-compression, absorption, and hybrid systems, despite toxicity concerns.
- Water and propane (hydrocarbon) have also been evaluated for specific GSHP applications, including absorption cycles and secondary fluid roles.
Conclusions:
- Natural refrigerants are promising for sustainable GSHP technology.
- Further research and development are needed to optimize the use of various natural refrigerants, addressing challenges like toxicity and system design.
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