Setting the Material Properties

Define the phases and set the appropriate material properties.

In this high-pressure calculation where wall dryout is not expected, the vapor remains at saturation temperature. Therefore it is valid to assume constant vapor properties and constant interface properties.

The liquid on the other hand can experience a significant change in density and in specific heat while it is heated from a subcooling of 60 K towards saturation temperature. Nevertheless a useful analysis can be made using constant properties for the liquid by respecting these two conditions:

• In order to obtain the correct heat balance, while also using the experimental inlet temperature, the following definition of liquid specific heat was chosen:

  $C_p=\frac{h_L^{SAT}-h_L^{IN}}{T^{SAT}-T^{IN}}$

  where SAT indicates saturation, IN indicates inlet, and L indicates liquid.

• The liquid density, viscosity, and conductivity are chosen at a temperature midway between inlet and saturation. The inlet velocity must be chosen such that inlet velocity times density matches the experimental mass flux.

In this tutorial, the process of setting the properties has been deferred until after all the models have been selected. Some properties appear only when demanded by particular models.