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CFD model development for a final effect evaporator

Pennisi, S.N., Liow, J-L and Schneider, P.A. (2004) CFD model development for a final effect evaporator. In: 26th Annual Conference Australian Society of Sugar Cane Technologists, 4 - 7 May 2004, Brisbane, QLD, Australia

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Abstract

The use of computational fluid dynamics (CFD) modelling tools in the engineering design process has become increasingly popular in recent times as a result of beneficial outcomes from several studies. Sugar mill Roberts evaporators are likely to have non-ideal juice flow characteristics and design improvements could be realised if a suitable computational model were developed. The model would be a useful tool for predicting broad trends in fluid flow behaviour when process equipment modifications are implemented. In this paper, a numerical model is presented for the single-phase fluid flow inside an evaporator vessel. The model is a one-quarter wedge of the entire vessel utilising two planes of symmetry to reduce the size of the mesh required. The model incorporates the effect of temperature and brix on the fluid properties. A heat source is used to model the heat flows through the calandria and momentum sources are used to model the effect of the vertical heating tubes in the calandria section and also the buoyancy forces generated by the production of vapour. A series of experiments was conducted to gather brix and temperature measurements at certain points within the juice space below the calandria. These data were compared with the predictions and used to judge the model's ability to predict fluid flow. The predictions show good agreement with factory data. Both the measured and predicted brix and temperature distributions are well mixed, with the majority of juice in the region below the calandria at conditions close to those reporting to the outlet. The model presented cannot predict the heat transfer performance of the calandria section and it has not been run outside the conditions normally encountered in a typical vessel. Both of these issues have been identified as direction for future development. The model has demonstrated its ability to accurately predict the fluid flows inside the entire vessel within these constraints.

Publication Type: Conference Paper
URI: http://researchrepository.murdoch.edu.au/id/eprint/38168
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