Modeling of carbon dioxide based air-to-air air conditioners.

摘要

The world-wide agreement to restrict the use of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has prompted recent research exploring the possibilities of replacement refrigerants, particularly those occurring naturally in the environment. One such natural refrigerant, carbon dioxide, has been considered for certain refrigeration and air conditioning applications. In order to evaluate the potential performance of a refrigeration cycle based on carbon dioxide, a cycle model has been developed which can simulate the operation of a carbon dioxide based air conditioner. This model is called ACCO2 and accounts for the effect of both thermodynamic and thermophysical properties of carbon dioxide.; ACCO2 simulates the operation of a carbon dioxide based air conditioner that uses air as the heat source and heat sink. The description of component models and the methodology to combine them into an overall cycle model (ACCO2) has been presented. ACCO2 was validated using experimental data and data from another validated air conditioner model. A parametric study has been conducted using ACCO2, a validated air conditioner model which uses HCFC-22 as the refrigerant, and experimental data from a HFC-134a based air conditioner.; Results compare the calculated/experimental Coefficient of Performance of each cycle given an equal evaporator capacity. Conclusions are drawn concerning improvements to ACCO2 and concerning carbon dioxide transcritical cycle device design considerations.