Ice accretion in cryogenic heat exchangers. Dimensioning, building, testing and validating a heat exchanger rig for freezing condensate for various future aircraft engine applications

Abstract

As research into future concepts of aircraft propulsion advances, hydrogen-powered aircraft are becoming a considered alternative. Given that hydrogen fuel is extremely cold and could benefit from heating before combusting, and excess heat from the engine exists, a heat exchanger could benefit the overall efficiency of such an engine. However, freezing is thought to occur due to the humid air and the cold fuel flowing through the heat exchanger. This project will therefore aim to investigate ice accretion in a cryogenic heat exchanger.

To achieve this, a test rig must be dimensioned and constructed. Using a standard compact heat exchanger as described in Kays and London’s Compact Heat Exchangers, the rig was drafted to replicate freezing conditions similar to those that could be expected in an aero engine. A parallel-running bachelor thesis ensured that the rig was constructed and functional in time for the testing phase of the project.

During the assembly of the rig, simulations in StarCCM+ were conducted, where icing effects were investigated using a multiphase model. The temperature drop used to dimension the heat exchanger was later compared to the observed results from the tests. The test results were visually compared to the ice propagation predicted by CFD.