A transient mechanistic two-fluid model for Direct Contact Condensation

Intensified heat treatment, using Direct Contact Condensation (DCC), is applied in the production of dairy products to ensure a high level of food safety. The key challenge with DCC is the protein reactions and fouling that limit operational efficiency and sustainability. The use of validated, transient models to predict temperature, phase fraction and velocity gradients is essential and can improve the operation of DCC. Pilot plant scale experiments were performed for a wide range of steam mass fluxes, inlet water temperatures, water Reynolds number and channel pressures to validate a transient 1D two-fluid model. The model was tested against steady-state experimental data and showed good agreement. In addition the model was tested against transient data in which either the water flow rate was step wise decreased or the pressure was adjusted throughout the experiment. In general the model followed the experimental trend well provided that the flow inside the channel is homogeneous.