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Thermodynamic performance assessment of carbon dioxide blends with low GWP working fluids used for heat pump water heater.

Number: pap. ID26

Author(s) : DAI B., LI M., DANG C., et al.

Summary

Carbon dioxide blends with 10 low GWP working fluids used for heat pump water heater were systematically evaluated, based on the method of pinch point with the specified temperatures of the heat transfer fluids. The effects of discharge pressure, mixture fraction, hot water outlet temperature and chilled water inlet temperature on the thermal performance of the system were analyzed detailedly. A maximum coefficient of performance (COP) was obtained at the corresponding optimal high pressure for various component ratios (XCO2). Adding low and medium GWP working fluids to pure CO2 can reduce the high pressure. For the mixture CO2/R41, the heat rejection process operated at supercritical state with a higher COP compared with pure CO2. For other binaries, it was supercritical cycle at high XCO2, but shifted to subcritical cycle at lower XCO2. The temperature glide in the gas cooler/condenser of the zeotropic mixtures can have a good match with the hot water. The temperature match in the evaporator played a leading role for the whole system performance. For low external (chiller water) temperature glide, CO2/R41 was recommend for its robust performance at various XCO2. In the case of moderate high external temperature glide (~10°C), CO2/R32 was more suitable for its relative higher COP and lower running pressure. For more larger external temperature glide (> 10°C), CO2/R1270 and CO2/R161 can be used for their advantage of larger internal temperature glide.

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Pages: 16 p.

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Details

  • Original title: Thermodynamic performance assessment of carbon dioxide blends with low GWP working fluids used for heat pump water heater.
  • Record ID : 30012191
  • Languages: English
  • Source: 11th IIR Gustav Lorentzen Conference on Natural Refrigerants (GL2014). Proceedings. Hangzhou, China, August 31-September 2, 2014.
  • Publication date: 2014/08/02

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