Pressure Drop in Protective Metal Meshes in Clean Low EGR Loop

Future NOx emissions limits are very difficult to meet with conventional high pressure EGR loop. This limitation causes diesel engine manufacturers to give much more attention to low pressure EGR systems. This configuration enables higher EGR flow rates and therefore lower NOx emissions at the same engine operation conditions. The implementation of low pressure loop ensures sufficient driving pressure for the EGR flow rate however conventional compressors are not specifically designed to endure the fouling of Diesel exhausts. An improved version known as clean low pressure loop takes the EGR source downstream of the diesel particulate filter keeping the compressor free of soot. The performance of the compressor improves substantially but it is necessary to protect it from eventual ceramic particles that can be discarded from the DPF. The use of a metal woven wire mesh in the EGR-cooler protects the compressor but introduces an additional pressure drop that must be taken into account in the cooler design.

This paper focuses on the development of a reliable tool, based on experimental results and CFD, that can predict the pressure drop in plain square woven mesh at different angles of incidence in such a way that project engineers may have reliable information about the pressure drop performance of these singular elements, that is not well documented in the literature except for the case of plain wire mesh perpendicular to flow. Comparison to literature with experimental tests is also made.