Experimental Investigation of the Pressure Drop during Water Condensation inside Charge Air Coolers

This paper investigates the pressure drop with and without condensation inside a charge air cooler. The background to this investigation is the fact that the stored condensate in charge air coolers can be torn into the combustion chamber during different driving states. This may result in misfiring or in the worst-case lead to an engine failure. In order to prevent or reduce the accumulated condensate inside charge air coolers, a better understanding of the detailed physics of this process is required. To this end, one single channel of the charge air side is investigated in detail by using an experimental setup that was built to reproduce the operating conditions leading to condensation. First, measurements of the pressure drop without condensation are conducted and a good agreement with experimental data of a comparable heat exchanger reported in Kays and London [1] is shown. In case of condensation it is observed that the accumulated condensate leads to an increase in pressure drop. An equilibrium state is established between the condensate formed and the one discharged from the charge air cooler, which leads to pressure fluctuations. Furthermore, the amount of the accumulated condensate in the charge air cooler is considered when determining the Fanning friction factor. It is shown that with this consideration the two-phase pressure drop can be described by the single-phase Blasius approach in the investigated operating range of the charge air cooler. The mean deviation of the measured data from the correlation amounts to about 3.8%.