Denso Corporation has developed the world’s first refrigeration cycle system for passenger vehicles that uses an ejector. The system is used for both an air conditioner and cooler box (vehicle refrigerator) and is installed on Toyota Motor Corporation’s Land Cruiser, launched in Japan in September. This system will also be installed in the Land Cruiser launched in October in North, Central and South America, Asia, and other regions throughout the world.

The car air conditioner and cooler box use the same refrigeration cycle. In a conventional refrigeration cycle, a solenoid valve switches between refrigerant flow for cooling in the air conditioner and refrigeration in the cooler box, which affects air conditioning performance when the cooler box is used. In contrast, the new system eliminates the solenoid valve and uses a small refrigerant injector called an ejector instead of an expansion valve (in the conventional refrigeration cycle, the refrigerant is cooled by outside air while it passes through the condenser; an expansion valve further cools the refrigerant by expanding it in the decompression process), which allows cooling via the car air conditioner and refrigeration through the cooler box simultaneously.

By using an ejector that rapidly injects and expands high-pressure refrigerant, the energy that previously was lost in the expansion valve is converted to pressure energy and reused, thus boosting energy efficiency (cooling capacity per power consumption; a larger value indicates higher efficiency). As a result, high cooling and refrigeration performances are both achieved even when the cooler box is used, reveals the company’s press release. “An ejector system can drastically improve the energy efficiency in the refrigeration cycle and we are now working to develop a system specifically for car air conditioning systems”, said Hikaru Sugi, managing officer in charge of Denso’s Thermal System Business Group.