AMMONIA AND CARBON DIOXIDE HEAT PUMPS FOR HEAT RECOVERY IN INDUSTRY

摘要

This paper presents a generic, numerical study of high temperature heat pumps for waste heat recovery inrnindustry using ammonia and carbon dioxide as refrigerants. A study of compressors available on the marketrntoday, gives a possible application range of the heat pumps in terms of temperatures. Calculations of cyclernperformances are performed using a reference cycle for both ammonia and carbon dioxide as refrigerant. Forrneach cycle a thorough sensitivity analysis reveals that the forward and return temperatures of the heat sinkrn(condenser or gas cooler) of the heat pump are most important for the coefficient of performance, COP. Byrncomparing the cycles it is found that for each set of operating conditions the two refrigerants perform equallyrnwell at one given inlet temperature of the heat sink. Above this temperature ammonia cycles have the bestrnCOP and below CO_2 cycles perform best. A general conclusion is that ammonia heat pumps are best at heatrnsink inlet temperatures above 28℃ and CO_2 is best below 24℃, independent of other parameters.