Fouling Problems in Exhaust Gas Recirculation Coolers in the Automotive Industry

Abstract

Transportation is responsible for approximately 20% of global greenhouse gas emissions, such as CO₂, NO_x, and hydrocarbons that have not been burned completely in the engine. In particular, 55% of globally emitted NO_x, which is more harmful to the environment than CO₂, is produced by the automotive industry alone. Strict emission standards are now in place that set specific limits to the amount of pollutants that can be released into the environment. The widely used measure to reduce NO_x emissions in diesel engines is to return part of the exhaust gas to the intake of the engine. This is usually done through a heat exchanger known as an exhaust gas recirculation (EGR) cooler. However, EGR coolers are subject to severe fouling such that their thermal efficiency can drop by as much as 30% within a very short period of time. More importantly, the deposit layer is a blend of particulate matter and sticky heavy hydrocarbons that are very difficult to remove from the heat exchanger surfaces. The present study addresses this problem and provides a review on required research and development (R&D) activities to mitigate fouling of EGR coolers.