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Propane heat pump with low refrigerant charge and advanced expansion valve control.

Author(s) : OTT S.

Summary

In the context of a potential realization of the f-gas regulation for stationary refrigeration applications the focus moves back to the so called natural refrigerants. The natural refrigerants mostly used are: carbon dioxide (CO2), flammable refrigerants (propane, butane, isobutane) and ammonia. In the past the so called flammable refrigerants have already been used in heat pumps, but due to a low customer acceptance and a lacking support on the part of the compressor manufacturers most heat pumps have been shifted to conventional refrigerants such as R-134a, R-404A and R-407C. To simplify the use of flammable refrigerants in fridges and freezers for household application regulations with reduced requirements on deployment have been adopted for refrigeration cycles with refrigerant charges less than 150 g. Based on these conditions an exhaust air heat pump with a heating capacity of 2 kW for space and tap-water heating has been designed. Using a refrigerator compressor and components especially designed for a low refrigerant charge a refrigeration cycle has been set up. To achieve a maximum COP an electronic expansion valve together with an advanced control algorithm is used to enable stable operation having a minimal superheating in every operating point and maximum utilization of the evaporator. Additionally the controller allows a "defrosting management based on the refrigeration cycle data" to ensure a minimal defrosting period, which improves the COP even further. First experimental results of the propane heat pump will be shown and compared with a CO2 heat pump having the same heating capacity.

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Pages: ICR07-E2-754

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Details

  • Original title: Propane heat pump with low refrigerant charge and advanced expansion valve control.
  • Record ID : 2008-0058
  • Languages: English
  • Source: ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Publication date: 2007/08/21

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