In the framework of the activities for the selection of an alternate refrigerant to comply with the R-134a ban, FIAT chose to develop a carbon dioxide (R-744) MAC system on a vehicle representing the FIAT portfolio.
The vehicle model was specifically selected to deal with two critical parameters in the low cost intermediate segment: a cabin compartment of comfortable size and a tiny engine compartment. The design target was therefore a MAC system featuring both a considerable cooling capacity and efficient packaging.
The prototype was built with the most up to date version of R-744 components available, allowing the evaluation of advanced technology, resulting in meaningful results.
General system and component specific issues are mentioned to explain the necessity of using additional components with respect to the typical R-134a MAC system (i.e. internal heat exchanger, accumulator, expansion device and externally controlled compressor). The complete set of results achieved in the first step of evaluation project, based on an extensive testing on a demonstration vehicle, is presented. The elements for the determination of the main contributors in a LCCP assessment are also reported.