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Experiments on the heat transfer characteristics of heat exchangers for a CO2 heat pump system.

Author(s) : GAO L., HONDA T.

Summary

The heat transfer characteristics of CO2 inside horizontal tubes which are used as a gas-cooler and an evaporator of a CO2 heat pump system were investigated experimentally. The experimental apparatus is a heat pump system. The test gas cooler and evaporator were double tube heat exchangers cooled/heated by water. The local heat transfer coefficient in the gas-cooler was compared with Gnielinski's correlation, which is the most well-known one used for forced convection heat transfer of turbulent flow. The results show that the local heat transfer coefficient of the gas cooler agreed well with the correlation except in the region near the pseudo critical temperature, while that at the region near pseudo critical temperature is higher than the correlation. When the concentration of lubricating oil was controlled at 1%, the local heat transfer coefficient is about 0 to 40% lower than those without oil. The local heat transfer coefficient of evaporation has been compared with the correlation presented by Mori et al. The results show that the local heat transfer coefficient of the evaporator is higher than the correlation except the dry-out region. When the concentration of lubricating oil is 1%, the local heat transfer coefficient is about 50% lower than that without oil.

Details

  • Original title: Experiments on the heat transfer characteristics of heat exchangers for a CO2 heat pump system.
  • Record ID : 2006-1138
  • Languages: English
  • Source: Green breeze from Asia: frontiers of refrigerants, heat transfer and system.. ACRA-2002. Proceedings of the Asian conference on refrigeration and air conditioning.
  • Publication date: 2002/12/04

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