Wednesday, September 14, 2011

New Phase Change Material (PCM) Evaporator by Delphi

A Frankfurt press release on September 14, 2011 reported on a new phase change material based evaporator for hybrid vehicles that provides efficient, affordable air conditioning even when the car engine is off. The release stated that Delphi Automotive is developing an air conditioning technology that saves energy without compromising cabin comfort. The product incorporates a Phase Change Material (PCM) in the Evaporator that is expected to keep the cabin of start-stop vehicles cooler longer. The new evaporator is expected to be a direct replacement for the original air-conditioning evaporator. It will lower the cost, will be less complex than an electric air conditioning compressor and is more efficient.

Delphi's system integrates a reservoir of PCM within the air-conditioning evaporator. During normal operation, PCM reservoir is kept cool such that the PCM material is maintained in a frozen state. When the air conditioning system is stopped, the PCM gradually liquefies or melts, drawing heat from the air to keep passengers cool and comfortable. The system can typically maintain target air temperature at the cabin vents for one to two minutes based upon the quantity of PCM in the reservoir. The system keeps the occupants comfortable throughout periods of stop-start driving while conserve fuel. 

As per the release, Delphi technologies can reduce HVAC system fuel usage by 50 percent.The technology is now moving from testing to its first vehicle development program and is expected on the road by 2014.

Read the full press release


  1. Nice work by Delphi. But I have a doubt. what will happen if the car A.C. is continuously ON and the air is too cold? won't the solid state PCM burst the the enclosure in which it is kept?
    Also how much quantity of PCM is enough?

    1. Niraj, this is just my opinion - not knowing which PCM was used by Delphi -the PCM expansion could take place while it liquefies. Generally the expansion is not more than 15% even if it was occurring during solidification. If adequate space is available in the reservoir, the enclosure may not be at risk. From the project, it looks like the duration of the stops is very short, the amount of PCM needed may be very small.