Automotive Air-Conditioning SystemsHistorical Developments, the State of Technology, and Future Trends

Automotive air-conditioning (A/C) or mobile air-conditioning (MAC) systems have played an important role in human comfort and to some extent in human safety during vehicle driving in varied atmospheric conditions. It has become an essential part of the vehicles of all categories worldwide. After discussing the basic operation of the A/C system, a brief summary is provided on historical development of the vehicular A/C system, with refrigerant history from the inception of the A/C system to future systems: R12, R134a, and enhanced R134a A/C system, and next-generation refrigerants having no ozone depletion potential in the stratosphere and global warming potential less than 150. The discussion also includes an enhanced MAC system with R134a, and the direct and indirect emissions from vehicles impacting global warming due to the use of the A/C system. This would explain why we continue to change the refrigerants in the automotive A/C system in spite of billions of dollars of cost for the previous refrigerant change (from R12 to R134a). The system design considerations are then outlined for minimizing the impact of A/C operation on the vehicle fuel consumption. Finally, new concepts of design of A/C system and vehicle heat load reduction ideas are discussed to further minimize the impact of A/C system operation on the environment without impacting human comfort. It is anticipated that this article will provide the overall and detailed prospective of the A/C system developments and provide an opportunity to the researchers to accelerate research and development for the refrigerant changeover and A/C system and component optimization and cost reduction.