Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures, the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends on the outlet temperature of the gas cooler, the evaporation temperature and the efficiency of the compressor. General correlations for this optimal heat rejection pressure were derived based on cycle simulations. The correlations presented in this paper provide a basis for designing transcritical carbon dioxide air conditioning or heat pump systems and for intelligent controlling such systems.
|Title of host publication||Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems|
|Publication status||Published - 1998|
|Event||Natural Working Fluids '98 - Oslo, Norway|
Duration: 1 Jan 1998 → …
|Conference||Natural Working Fluids '98|
|Period||01/01/1998 → …|