EGRkoeler

An EGRkoeler, or exhaust gas recirculation cooler, is a heat exchanger placed in the exhaust gas recirculation (EGR) loop of an internal combustion engine. Its main purpose is to lower the temperature of the recirculated exhaust gas before it mixes with the intake air, which helps reduce peak combustion temperatures and lowers nitrogen oxide (NOx) emissions. Cooler EGR gas also allows higher EGR rates without causing excessive charge cooling or misfire.

Most EGR coolers are water-cooled, using the engine’s cooling system as the heat sink. Some designs use oil cooling, or integrate the cooler with the EGR valve assembly. The heat exchanger is typically a plate-fin or tube-and-shell type, with the exhaust gas on one side and a cooling medium on the other. The cooler is commonly located in the EGR loop between the exhaust manifold and the intake manifold or inlet to the EGR valve, depending on the engine layout.

Maintenance and reliability considerations include buildup from soot and carbon, which can restrict flow and reduce cooling effectiveness. Failures can involve clogging, or leaks that allow coolant to enter the exhaust stream or exhaust gases to contaminate the cooling circuit. Symptoms may include reduced EGR flow, elevated intake gas temperatures, coolant loss, white smoke, or engine overheating, often accompanied by diagnostic trouble codes.

EGR coolers are used on many diesel and gasoline engines, particularly where stringent NOx emissions targets are required. They are a key component in controlling exhaust gas temperature and enabling effective EGR operation.