Recent advances and sustainable solutions in automobile air conditioning systems

The regulations regarding emission and air conditioning in the automobile sector have become more stringent worldwide. Air conditioning (AC) is an integral component of an automobile to provide human comfort. For many years, the AC systems in automobiles widely used the vapour compression refrigeration (VCR) method. However, operating automobile AC using a VCR system has high energy consumption and negative environmental impacts. Thus, increasing fuel consumption of conventional vehicles and reducing the driving range of Electric Vehicles (EVs). The significant challenge currently faced is fighting these environmental regulations, reducing fuel consumption of traditional vehicles, and increasing the cruising range of EVs. Although a substantial amount of research was conducted during the last three-four decades, the automobile sector is yet to explore sustainable AC systems. A detailed investigation of various automobile AC systems, categorizing them into active, passive and hybrid AC systems and their interrelation with the vehicle's performance, is presented in this review article. We reviewed, compared, and provided a comprehensive description, and the main resulting enhancements of each AC system category are presented. In addition, applications of hybrid AC systems are discussed with indicating main improvements in energy and fuel consumption. Besides developing these energy-efficient AC systems, the most critical challenge encountered is linked to the automobile standards and regulations that are the main obstacle in taking these new research ideas to commercialization. Within the information and knowledge promulgated in this review article, the evolution and glance of the future insight on alternative environmentally friendly and energy-efficient automobile AC systems after the VCR system can be expedited.