Heat exchanger for exhaust duct in IC engine has a concentric pipe construction with the flow pattern changed for high pressures and high flow rates

摘要

A heat exchanger for the exhaust duct from an IC engine has a concentric construction with an inner duct for direct through flow and outer pipe (12) to form an outer duct. The inner duct has a flow restriction (17) which has limited effect at low pressures and flow rates. At higher pressures and flow rates the pressure build-up in front of the flow restriction causes a proportion of the gas flow to flow through perforations (14) into the outer duct and back into the exhaust via other perforations (15) at the end of the heat exchanger. The increased surface area of the outer duct provides enhanced cooling at higher engine powers. The heat exchanger operates without control flaps and controls the temperature of the exhaust gasses into the catalytic converter.