Denso, Witzenmann prep for CO2

Denso Corp. will be ready in the event the auto industry adopts carbon dioxide (CO₂) as an air-conditioning refrigerant in future vehicles.

The world's top supplier of climate control systems supports CO₂ because it is an abundant refrigerant, has a negligible effect on the environment and can be used for heat-pump systems in electric or hybrid vehicles.

But using CO₂ in automotive is no simple task. The operating pressure of a CO₂ system is 10 times higher than that of a conventional AC system, so it requires a different heat exchanger and re-engineering of every component.

A CO₂ system can provide both heating and cooling. In current systems, heat comes from, ironically, the engine coolant. CO₂ is becoming necessary because today's engines are so efficient that they do not generate enough waste heat to warm the cabin adequately, Denso says.

Denso acknowledges the topic of CO₂ is controversial because certain regions of the world, including parts of the U.S., may have no interest in switching to CO₂ as a refrigerant.

At its own SAE press conference, Witzenmann GmbH says it expects to begin European production in 2004 of complex metal hoses for an automotive AC system that runs on CO₂.

Witzenmann's end customer likely will be Mercedes-Benz, which has said it will use CO₂ as a refrigerant in a vehicle around 2005. It is not clear which supplier will produce the AC system for Mercedes. Denso said it did not have a customer for a CO₂ AC system.

Witzenmann would produce only the hoses necessary for carrying the CO₂ gas as part of the AC system. The hoses are a crucial part because the gas is heavily pressurized, and the hose must withstand pressures of up to 10,000 lbs./sq.-in. (69,000 kPa).