(photo: Delphi Automotive PLC)
by Jacques Gordon
Imagine sitting at a red light in a vehicle equipped with Auto Stop technology. Normally the engine would shut down to save fuel, but it’s a hot day and the A/C is running, so the engine keeps running to keep the compressor running. So much for gas mileage. But if the evaporator contains Delphi Automotive’s new Phase Change Material (PCM) technology, you don’t need to choose between economy and comfort. The engine can shut down to save fuel because when the compressor stops running, cold air will still flow from the vents.
Utilizing “thermo siphon” principals first described in the 1800s and applied in NASA spacecraft in the 1960s, Delphi has developed an air conditioning evaporator capable of “storing cold” that can be released when the compressor is not running. It’s only slightly larger and heavier than a normal evaporator, and with proper engineering of the rest of the A/C system, the system can still achieve the same vent temperature without the compressor running for 90 seconds or longer.
The PCM section of the evaporator is filled with a special paraffin that changes from solid to liquid in just the right temperature range. It can repeat the process time after time with no deterioration in performance, similar to the wax pellet in a cooling system thermostat. After the vehicle starts moving and the compressor starts running again, the PCM is “recharged” (cooled to a solid) within about 30 seconds, so the system performs even in stop-and-go traffic.
Delphi displayed their PCM evaporator at the recent SAE World Congress. Although not in production yet, we expect this technology will become as common as the evaporator itself in the not too distant future.
The Mobile Air Conditioning Society’s blog has been honored as the best business to business blog in the Automotive Aftermarket by the Automotive Communications Awards and the Car Care Council Women’s Board!
When having your mobile A/C system professionally serviced, insist on proper repair procedures and quality replacement parts. Insist on recovery and recycling so that refrigerant can be reused and not released into the atmosphere.
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The 35th annual Mobile Air Conditioning Society (MACS) Worldwide Training Conference and Trade Show, Meet me at MACS! will take place February 5-7, 2015 at the Caribe Royale Hotel and Convention Center.