ISBN 9783843952682

978-3-8439-5268-2, Reihe Thermodynamik

Irina Basler
Development of a Simulation Method for Calculating the Condensation of Water inside Charge Air Coolers

187 Seiten, Dissertation Universität Stuttgart (2023), Softcover, A5

Zusammenfassung / Abstract

The objective of this thesis is the development of a simulation method to calculate the condensation of water inside charge air coolers. For this purpose, an air-cooled charge air cooler with plain fins and a water-cooled charge air cooler with louvered fins are investigated. Since defined boundary conditions are required for the validation of the simulation method, only one single channel of the entire charge air cooler is examined. To this end, the operating points relevant to condensation are identified and an experimental setup is built.

The developed simulation method comprises a porosity model to represent the internal structure with the fins in combination with a condensation model, which calculates the condensation rate and the amount of accumulated condensate. Both quantities are measured during the experimental investigation to validate the simulation method. In addition, the Fanning friction and the Colburn factors of the charge air coolers with and without condensation are determined. They serve as input variables for the simulation to reproduce the behavior of the charge air coolers in terms of pressure drop and heat transfer. Since the flow through plain fins differs from that through louvered fins, two different types of condensation models are implemented. The condensation model used for the plain fins is based on the boundary layer theory of a flow over a flat plate with surface suction. The other condensation model exploits the fact that the boundary layer rebuilds at each of the louvered fins. It considers the condensation at each fin separately by combining Nußelt's film theory with the boundary layer theory.

Eventually, the results of the developed simulation method are in good agreement with the experimental results. The comparison of the condensate retention of a single channel with an entire charge air cooler shows that at low Reynolds numbers significantly less condensate accumulates in a single channel.