Searching for eco-friendly working fluids for an ejector-driven heat pump for domestic water heating

Conference · Mon May 01 04:00:00 EDT 2023

OSTI ID:1976014

Mohammed, Ramy H. ^[1]; Spitzenberger, Jeremy ^[1]; Wang, Pengtao ^[2]; Ma, Hongbin ^[1]; Abu heiba, Ahmad ^[3]; Kowalski, Steve ^[2]; Nawaz, Kashif ^[2]

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1. University of Missouri, Columbia
2. ORNL
3. Honeywell International

This study searches for refrigerants with low global warming potential (GWP) and zero ozone depletion potential (ODP) for an ejector heat pump water heater (EHPWH). Several criteria are set, and R1336mzz(Z), R601a, R1233zd(E), R1224yd(Z), R1234ze(Z), and R600a are shortlisted. A theoretical model is built to study the performance of EHPWH and the corresponding ejector design at different operating conditions. For the same ejector design, a refrigerant with a high specific heat ratio produces a high entrainment ratio and heating COP. This is because the expansion wave angle in the ejector is small for refrigerants with a high specific heat ratio, allowing more mass flow rate to be entrained. A higher entrainment ratio does not necessarily correlate to a high COP because the saturation curve of the tested refrigerants is not the same. Results show that the heating COP of R601a is the highest, but it is extremely flammable. R1224yd(Z) and R1234ze(Z) are the most candidates for EHPWH when the trade-off between the COP and safety criteria is considered. The results presented in this work could help building an EHPWH using eco-friendly refrigerants.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1976014
• Country of Publication: United States
• Language: English