The post processing features allow observation of velocity and temperature profiles as well as calculation of heat flux, average heat transfer coefficients, and an estimate of the thermal boundary layer thickness, δ t. Then we solved the convection and conduction model using the results from the k- ε model for flow behavior. We solved the two models separately by solving the k- ε model first using fluid properties at an estimated average temperature. Our heat exchanger model uses the k- ε model for the momentum balance together a conduction and convection energy balance model in COMSOL’s Chemical Engineering Module to predict outlet water temperature given inlet water flow rate, inlet water temperature, and steam temperature. Since our students are not familiar with COMSOL Multiphysics or the k- ε model we have prepared a tutorial that begins with a simple laminar flow heat exchange process and explains the basics of turbulence modeling before discussing the more complex turbulent flow heat exchanger described here. Fortunately, COMSOL Multiphysics has a built-in k- ε turbulent flow model that provides the appropriate 16 modifications to Equation 2 to account for fluctuating turbulent eddies.

One complication not yet noted is that the water is in the turbulent flow regime. Multiphysics makes it relatively easy to obtain numerical solutions to Equations 1 and 2, the differential equations that underlie the momentum and energy balances for our process.

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