On one hand, the urgent need to address the massive release of refrigerants and its detrimental impact on the environment calls for the swift adoption of environmentally-friendly refrigerants in automobile air-conditioning systems. On the other hand, the utilization of carbon dioxide in heat pump water heaters is paramount. With carbon dioxide releasing heat under supercritical conditions, it allows for a substantial temperature glide, enabling the heating of hot water to higher temperatures. Furthermore, the impressive low-temperature flow performance and heat transfer characteristics of carbon dioxide make it an ideal choice for implementing it as a refrigerant in the cascade refrigeration cycle. Taking all these aspects into consideration, it is evident that embracing non-harmful refrigerants and capitalizing on the unique properties of carbon dioxide is crucial in various applications within the realm of thermal control.