Performace Comparison of HFC-134a and CFC-12 in a Heavy Truck Air Conditioning System

This paper reviews vehicular wind tunnel tests performed on a heavy truck air conditioning system utilizing refrigerants HFC-134a and CFC-12 with various condensers. Refrigerant type was found to have little effect on system temperatures but considerable effect on system pressures. Condenser design was able to compensate for the increased pressures induced by HFC-134a. Condenser design also affected refrigerant charge weights of both refrigerants. Refrigerant charge weights are important today because of limited supplies of CFCs, and will be important in the future when more costly HFC-134a becomes the standard refrigerant. Structural durability of the compact, lightweight PF® condenser was found to be acceptable for heavy truck applications.

REVISIONS RECENTLY MADE to the Montreal Protocol by its signatory nations have shortened the timetable for phaseout of ozone-depleting compounds. One of these, CFC-12, has long been the standard refrigerant for heavy truck air conditioning systems. The most promising environmentally safe refrigerant for replacement of CFC-12 is HFC-134a. The automotive engineering community is rapidly determining what changes in air conditioning system design are necessary to cope with HFC-134a. This paper concentrates on heavy duty truck A/C systems. It compares the performance of CFC-12 and HFC-134a during tests conducted in a “vehicular” wind tunnel and explains the influence of condenser design on system performance with HFC-134a.