Heat exchangers for hydrogen tank filling

The purpose of this report is to give some basic facts about heat exchangers and summarize a series of simulations done on counter-flow concentric tube heat exchangers for hydrogen gas bunkering using the COMSOL Multiphysics software. Part 1 of this report consists of an exploration of how various system parameters (flowrates, pressures, and tube dimensions) influence the properties of a heat exchangers based on pure water as coolant. Part 2 discusses how the heat exchanger performance can be improved using ethylene glycol-water mixtures and compares these results to those using pure water coolant. The Appendix gives tables of heat transfer coefficients for heat exchangers of different sizes using pure water and ethylene glycol-water mixtures.