Theoretical performance comparison of CO2 transcritical cycle technology versus HCFC-22 technology for a military packaged air conditioner application

The world-wide agreement to restrict the use of chlorofluorocarbons (CFCs) and hydrofluorocarbons has prompted research into the possibilities of repl acement refrigerants, particularly those occurring naturally in the environ ment One such natural refrigerant, carbon dioxide, has been considered for certain refrigeration and air conditioning applications In order to evaluat e the potential performance of a refrigeration cycle based on carbon dioxid e, a cycle model has been developed which can simulate the operation of a c arbon dioxide based refrigerator/air conditioner. This model is called ACCO 2 and accounts for the realistic effects of the thermophysical properties o f carbon dioxide. The model simulates the operation of a carbon dioxide based air conditioner that uses air as the heat source and heat sink. A parametric study has bee n conducted using ACCO2 as well as a validated cycle model which simulates the operation of an HCFC-22 based packaged air conditioner designed for use by the U.S. Army in a combat environment The size and weight constraints o f this application render HCFC-22 based units less efficient than typical H CFC-22 unitary air conditioners of the same capacity. it is hypothesized th at these same constraints will not affect the performance of a carbon dioxi de based packaged air conditioner as severely. The evaporative capacity, co mpressor power, and COP were calculated for each cycle, over a range of ind oor and outdoor temperatures, and used as a basis for comparing the two cyc les.