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Abstract

The problem of forced convective heat transfer to a suspension of small solid particles in a liquid is treated by developing a homogeneous equilibrium flow model. Suitable average properties are determined for the mixture which is then treated as a pseudofluid, obeying the usual equations of single-component flow.

The evaluation of suspension effective thermal conductivity from component values is considered first. Following a critical examination of the approach assuming a unidirectional heat flux, two digital simulation models are developed which eliminate this restriction and the requirement for a rigid geometric arrangement of phases. Thermal conductivity values are determined through solving a three-dimensional Laplace equation, using a finite difference technique, to give a steady state temperature distribution for boundary conditions derived from consideration of the Fourier rate equation. Effective thermal conductivities of several aqueous metallic powder suspensions have been experimentally determined using the relative plane horizontal layer method. Overall mean errors in prediction of 2.55 and 6.64 per cent were obtained for the two models, Theoretical and experimental results from previous studies have been used in a comprehensive examination of prediction methods.

The second section develops the homogeneous flow model. An existing numerical solution technique for the boundary layer equations is adapted for use with two-component fluids through the identification of effective two-component property relationships. An eddy diffusivity model based on the mixing length concept, which is developed and shown to be valid for single component flows, is modified to extend its use to the two component case. Evaluation of the technique, using the experimental results of Orr and Dalla Valle indicates an overall solution prediction error of 5.5 per cent. Further examination of results for individual suspensions indicates the range of suspension solids for which the model is strictly valid.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology T Technology > TA Engineering (General). Civil engineering (General) T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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