capacity substitutes for the latent heat of evaporation as the main contributor to cycle efficiency as a consequence the theoretical coefficient of performance for the specific cycle shown in fig2 is high calculated to be 9 1 heat removed divided by compression work inputted by way of contrast a carbon dioxide transcritical cycle operating at 46 bar on the low side and 110 bar on the high side would achieve a cop only about half as high despite the advantage of the latent heat of evaporation a comparison with r 134a in a vapor liquid cycle also shows advantages for the single phase supercritical carbon dioxide cycle as disclosed in the current invention the volumetric flow rate of co 2 for a given amount of heat removal is not quite half that required of r 134a this allows for the use of a smaller heat rejecting heat exchanger additionally a smaller ratio of inlet to outlet density through the compressor compared to r 134a allows for a smaller compressor lastly carbon dioxide is environmentally benign while r 134a along with other fluorocarbon based refrigerants is associated with the atmospheric greenhouse effect the basic components of a system employing single phase supercritical carbon dioxide as the coolant are shown in fig3 the cooling loop 1 serves to absorb heat 10 emanating from a heat generating device by circulating cool supercritical fluid through heat accepting heat exchanger 11 for the sake of clarity it is to be understood that in the present invention carbon dioxide is converted to a supercritical state by means of a separate device and is loaded into the cooling loop as a supercritical fluid the heat accepting heat exchanger may be constructed in any.