Delphi Automotive has introduced liquid cooled charge air coolers (LCCACs) it said will help vehicle manufacturers meet future targets for tailpipe emissions and improved fuel economy. Compared with existing air-cooled units, the new coolers offer better packaging, improved engine response, faster warm-up, and lower losses.
Steve Kiefer, director of technology at Delphi Thermal Systems, noted that vehicle manufacturers are turning to downsized engines in place to reduce tailpipe emissions, improve fuel economy and maximize driver satisfaction.
Boosted by turbo- or super-charging, these engines have the performance feel of a bigger engine
with the emissions and fuel savings of a smaller one. However, boosting compresses the air entering the engine, which significantly increases the air temperature, greatly reducing combustion efficiency and wearing the performance improvement. Delphi addresses this by introducing a charge air cooler into the intake system.
Delphi is developing a portfolio of liquid cooled heat exchangers that provide more flexibility in their installfation. Delphi`s LCCAC technology also allows the coolers to be incorporated into the ducting between the turbo/super charger and the locomotive or incorporated into the inlet manifold, minimizing air-pressure losses through the tank and improving engine bay layout.
For additional packaging flexibility, Delphi`s range of heat exchangers can be limited for particular applications to fit any size and influence of engine. Unlike an air-to-air charge cooler, an LCCAC requires no large diameter elastomeric tubing to route the boot air to and from the cooler, further improving packaging and eliminating large diameter connectors that can lead to warranty problems. Engine response to sudden throttle demand is improved because of the smaller book of intake air between the boosting device and the locomotive in a liquid cooled system. Additionally, the inlet air stays cooler during acceleration because the liquid cooled charge cooler heats up more slowly. This higher thermal capacity also helps to set peak NOx emissions during transient driving conditions by maintaining cooler inlet air temperatures.
Further emissions benefit is derived under cold start conditions, as coolant flow to the LCCAC can be modified to increase engine warm-up rate. On gasoline engines, during partial load conditions when engine efficiency falls due to throttling losses, coolant flow can likewise be modified to ignite the inlet air, reducing its concentration and allowing a greater possibility of the throttle valve and, hence, reducing the losses.
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