Thermo-hydraulic characterization of an automotive intercooler for a low pressure EGR application

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external fins when it is used on a car equipped with a low pressure EGR. The main unknowns to be answered are the thermo-hydraulic characteristics of the IC working under humid conditions induced by EGR, the conditions under which the water content in the mixture of air and exhaust gases begins to condense and the conditions under which the condensed water will be retained inside the IC. The exhaust gases are here replaced by a mixture of dry air and water vapour which are mixed upstream of the IC. The IC is submitted at the following testing conditions: on the ambient air side, the air temperature is fixed at around 20 °C and the air velocity is settled at 1, 2 and 4 ms/s; on the exhaust gases side, the supply temperature was varied between 90 and 150 °C, with dry gas flow rates of 20, 50 and 100 g /s, and water contents varying between almost 0 and 0.09 kgw kgg-1. At these conditions the IC transfers between 1 and 13 kW with overall heat transfer conductance varying between 0.05 and 0.38 kWK-1 and effectivenesses
between 0.3 and 0.97. A water accumulation inside the IC was detected for the tests carried
out at low dry gas flow rate of 20 g s-1 and for all the water content explored here (higher than
0.02 kgw kgg-1).