Analysis And Optimal Design Of The Enhanced Heat Transfer And Flow Resistance Within Finned Tube Heat Exchangers

Heat exchanger is an important component, which has been widely used in chemical engineering, energy engineering and air separation industries etc. With the rapid development of the air separation industry, air separation devices become bigger and bigger. It is necessary to make the heat exchanger more efficient to reduce the volume of the air separation equipment and to save the material expense. There are several technologies to enhanced the coefficient of heat transfer. For those having big difference of heat transfer coefficient between two sides flow, usually the side with low heat transfer coefficient use finned-tube to increase the whole heat transfer coefficient. In this paper, an inter-cooler of air compressors is studied as an example. Its heat transfer coefficient influenced factors, such as fin space, fin type, flow speed, pressure drop etc, are investigated systematically by CFD method combining experiment study. The main contents and results of the thesis are as follows:1、Numerical simulation method was applied to analyze air-side heat transfer and fluid flow characteristics of heat exchangers, including plate finned-tube heat exchangers and slit finned-tube heat exchangers. Comparing the air-side velocity field, pressure field and temperature field of different finned-tube exchangers reveals that the slits can promote mixing of the fluid and breaking the boundary layer, leading to an improvement in the performance of finned-tube heat exchanger.2、Method of control variable was employed to analyze the influence of air inlet velocity and geometric parameters (fin pitch, slit height, thickness of the fin and tube alignment etc.)on the heat transfer and the pressure drop performance of the slit finned-tube heat exchanger, which provides a theoretical basis for optimal design of the finned tube heat exchanger.3、Orthogonal combination method was applied to obtain the effects of different geometric parameters on the heat transfer and the fluid flow performance of heat exchangers. Thus the optimal geometry parameters were given. The results show that a slit finned-tube heat exchanger has the best performance with a fin pitch of 1.8mm, slit height of 1.08mm, thickness of the fin of 0.3mm. While the heat transfer and the flow resistance experimental results show that the optimal result matches experimental result well.In this thesis, the research on the finned-tube heat exchanger provides a significant guidance for the design and optimization of heat exchanger’s engineering design and industrial applications.