Discussion Forum

I am trying to model a simple high temperature hydrogen heat exchanger with the conjugate heat transfer module. While I have been sucessfull in modeling individual tubes of the hydrogen alone, I cannot seem to get a model with multiple tubes working.
In this model, half of a 3 tube heat exchanger is modeled with the outer shell excluded. A temperature dependent heat flux (temperature dependent as it takes into account radiation losses) is applied to the outer wall of the model. Symmetry is used to reduce computational time. While a custom mesh is used here, the comsol generic mesh was also tried. My mesh significantly reduces the memory used and allows for a much better distribution of resolution however.

For this model, I used the results from my single tube model of the hydrogen to provide the initial results. The text files include in the zipped folder consist of the data for these functions. All of the functions used here are to input these results as the initial conditions of the hydrogen.

For some reason, I continuously get the error "Inconsistent uni-directional constraint". I assume this means there is some error in the coupling of the heat transfer and fluid flow physics, but exactly what that is I have no idea. In addition to using the conjugate heat transfer module I have also tried manually coupling heat transfer in fluids and low Re turbulent flow modules but I get the same error. Does anyone have any ideas?