The analysis presented in this thesis is an application of the finite element method to the determination of the temperature, moisture content and pressure distributions within a capillary porous body. Luikovs system of partial differential equations, which are based upon the thermodynamics of irreversible processes, are used to describe the heat and mass transfer phenomena. Earlier research into this field assumed that the sole method of moisture transfer was by diffusion and that the pressure gradient within the capillary porous body was negligible and did not affect the solution. In this thesis, it is demonstrated that the presence of a pressure gradient arising within the body, which causes a filtration transfer of moisture to occur, can have a significant effect upon the transient temperature and moisture content solutions. Three numerical models were developed, firstly, a fully non linear model, where all material properties are permitted to vary, and secondly, partially non linear models for homogeneous and non homogeneous problems, where some material properties are held constant and the concept of moisture potential is introduced. The computational model was applied to the specific problem of freeze drying of coffee and the numerical solutions were compared with experimental results to validate the model.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:636970 |
| Date | January 1991 |
| Creators | Ferguson, W. J. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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