Heat transfer , condensation and fog formation in crossflow plastic heat exchangers
-In this paper heat transfer of air-water-vapour mixtures in plastic crossflow heat exchangers is studied theoretically and experimentally. First, a model for heat transfer without condensation is derived, resulting in a set of classical differential equations. Subsequently, heat transfer with wall condensation and fog formation are considered in some detail. Separate attention is paid to the heat transfer and condensation of pure steam in the heat exchanger. Finally, the experiments performed are reported and the results compared with the models presented. From this comparison it can be learnt that the models are well able to predict the rate of heat transfer and phenomena such as condensation and fog formation.
Polymer composites for thermal management: a review
Abstract The aim of this review article is to consolidate the important research works dedicated to polymers which are mainly used target material for heat transfer applications. The requirement of present day heat transfer equipment is compactness, lightweight, manufacturability, and lower cost. Materials like copper and aluminum though have better thermal conductivity but they are expensive and also heavy. Polymers are cheaper and easy to manufacture, recycle though they have sufficiently lower thermal conductivity compared to copper and aluminum. Polymer materials are thermally insulating material. It is too difficult to improve the amorphous nature of polymer material in order to achieve high thermal conductivity. One key path to increase the thermal conductivity of a polymer is to reinforce high thermal conductive fillers in the host matrix. In this review paper, an attempt is made to explore and summarize various key paths suggested by the researchers to develop high thermal conductive polymer composites.
Effects of non-condensable gas on laminar film condensation in a vertical tube
This paper develops a theory to reveal the effect of small amounts of non-condensable gas on laminar filmwise condensation of a vapour-gas mixture flowing turbulently in a vertical tube. The reductions in heat transfer due to the non-condensable gas are found to be more significant at low pressures and at low Reynolds numbers of the mixture. Comparisons of the theory with some experimental data reported in the literature are in good agreement.