Numerical study of the effect of buoyancy on conjugate heat transfer in simultaneous turbulent flow in parallel pipelines

This paper presents a numerical study of conjugate heat transfer between two air flows circulating in parallel pipelines. We analysed the buoyancy effect generated by the temperature gradient, by coupling the movement produced by the air flow forced through the entrances of the input ducts. The buoyancy effect favours a rapid transition to turbulence. The governing equations were solved using the finite volume technique. The variables were the Reynolds number in a range from 10 to 1000, and the aspect ratio values of 5, 25, and 50. The results show the importance of buoyancy on the performance of the heat exchanger. Furthermore, it was found that at low Reynolds numbers, buoyancy did not favour heat exchange effectiveness of increasing heat across the length of the channels. Furthermore, when the Reynolds value is 1000, we conclude that heat transfer is not affected by the buoyancy. Therefore, efficiency of heat exchange depends mainly on the length of the channels.