ESTiG - Artigos em Proceedings Não Indexados à WoS/Scopus
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Browsing ESTiG - Artigos em Proceedings Não Indexados à WoS/Scopus by Author "Afonso, Isabel M."
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- A comparison between heat transfer correlations obtained from experimental data and numerical simulation of flow of stirred yoghurt during cooling in plate heat exchangersPublication . Afonso, Isabel M.; Fernandes, Carla S.; Maia, João M.; Melo, Luis F.Thermal processing is widely used in the food industry mainly to improve quality and safety of food products. The investigation of heat transfer problems of non-Newtonian fluids during heating and cooling in heat exchangers is of major interest since the main factor limiting heat transfer is the viscous behaviour of these fluids. Therefore, the knowledge of the interface heat transfer coefficients is important in the design of food processes and processing equipment. In the present work, simulations of stirred yoghurt cooling in a plate heat exchanger were performed using computational fluid dynamics (CFD) calculations and the obtained results were compared with experimental data. Simulations were carried out using the commercial finite element method package POLYFLOW, being the geometrical domain the representation of a single 3D channel of the plate heat exchanger with a 30º corrugation angle. The correlation obtained numerically was compared to the one obtained from previous experimental work and they were found to be very similar to the experimental one. The constitutive model, under the assumptions used, was found to be a very good approximation for predicting the convective coefficients of stirred yoghurt during cooling in a plate heat exchanger.
- Influence of corrugation angle in the stirred yoghurt processing in plate heat exchangersPublication . Fernandes, Carla S.; Afonso, Isabel M.; Melo, Luis F.; Maia, João M.Research on heat transfer of non-Newtonian fluids during thermal processing is very useful for optimise heat exchanger design, as well as to define quality levels of the final product. In the present study non-isothermal, non-Newtonian flow in plate heat exchangers were simulated numerically, in order to evaluate the influence of corrugation angles on the thermal and hydrodynamics characteristics of yoghurt cooling in a plate heat exchanger. Simulations were carried out using the commercial finite element method package POLYFLOW, being the geometrical domain the representation of a single 3D channel of the plate heat exchanger. Two corrugation angles were considered, 30º and 60º, being the obtained numerical results for the first one compared with experimental data. A laminar flow was observed for the two cases and the decrease of the angle conducted to a decrease of pressure drop and maximum shear rate.