The falling film flow of milk was studied both analytically and experimentally. Experiments were carried out for concentrations from 19.93% to 62.09% to obtain the rheological data of milk while analytical studies were done to derive the solutions of the problem. Studies which include calculations and simulations were carried out for a typical milk flow in a falling film evaporator.
It was found that milk was non-Newtonian at high concentrations and Herschel-Bulkley model was able to model the milk flow. The typical falling film flow was able to be simulated as a two phase flow in COMSOL to gain a better understanding of the flow. It was found that there were counter-current flow between the film and air in the evaporator.
A Matlab program was also used to study the analytical solutions of the film temperature change while it flows down the tube with results showing that heat transfer was not linear as would have believed. Results from several experiments also enabled the change of milk viscosity with time to be modeled. Milk viscosity increased steadily with time and higher at higher total solids from 35.47% to 49.25% for three hours.
Calculations revealed that film thickness of milk was very thin, from 0.00116 m at the entrance of tube to 0.00146 m at the tube exit. From the use of models developed of the rheological parameters, results showed that these parameters have impacts on film flow except the yield stress. However, the viscosity and yield stress are factors that will limit the operating range available for falling film evaporator.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/6720 |
| Date | January 2011 |
| Creators | Ang, Keng Lin (Jason) |
| Publisher | University of Canterbury. Chemical and Process Engineering |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Jason Keng Lin, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
Page generated in 0.0019 seconds