Denso downsizes exhaust gas recirculation systems
Compact coolers are 30% smaller
- Published in Technology.
Pretty cool: narrower fins mean greater heat transfer
Denso has developed a compact exhaust gas recirculation (EGR) cooler for gasoline engines, which it says is almost a third smaller than the nearest competitor. The first applications are the Toyota Camry and Prius sedans.
Cooled EGR systems enable gasoline engines to be dethrottled, improving fuel efficiency and reducing CO2 emissions. They can also reduce the amount of full-load enrichment needed for highly boosted downsized engines, which also improves efficiency. Smaller, lighter EGR coolers are easier to package in the engine bay.
Executive director of Denso's thermal systems group, Akio Shikamura, said: “As OEMs look to downsize engines to help meet increasingly stringent regulations, EGR systems are becoming more necessary to improve combustion and fuel economy. Size reduction is a major factor in development: our compact cooler will greatly help reduce EGR system size.”
Better manufacturing processes have enabled the Tier One to increase the density of fins in the stamped heat exchanger plates. Instead of typical 5mm-wide slits made in the sheetmetal to produce the fins, Denso has achieved 1mm, dramatically increasing fin surface area within a given EGR cooler size, increasing cooling performance.
Heavily downsized gasoline engines will use higher boost pressures, which will mean higher EGR rates at higher loads, and therefore greater heat rejection to the EGR cooler. OEMs are unlikely to allocate more packaging space for the EGR system so more compact coolers will be needed.
Denso's EGR cooler is well-suited to applications such as these, and the firm is also developing coolers for the low pressure EGR loop used to cut NOx emissions from diesel engines.
