Staying Cool When the A/C Stops

Denso Corp. has developed an automotive air-conditioning evaporator unit with a special core that stores cold during normal operation and releases it when the A/C stops temporarily.

The so-called Cold Storage (CS) Evaporator is intended for cars with automatic idle-stop systems that shut off the engine and thus the A/C when the vehicle stops at a traffic light.

An evaporator cools the air passing through it by allowing refrigerant to change from liquid to gas inside a sealed array of tubes. But the flow of refrigerant stops when the vehicle's engine, which powers the A/C system, switches off. In a conventional system, the cooling effect quickly ebbs until the engine restarts.

Denso's system sandwiches insulated-filled cases between the evaporator's tubes. The cases store cold during normal A/C operation and transfer it to the evaporator's tubes when the A/C stops, thus prolonging the system's cooling action.

The CS Evaporator debuted in Japan last week in Suzuki Motor Corp.'s tiny Wagon R "tall" wagon. Denso says it intends to eventually roll out the design to unspecified new models worldwide.