The Research For Characteristics Of Convection Heat Transfer In Fluid Flow Over Bare Tube Banks

As we all know, the heat transfer is generally realized by conduction, convection or radiation and the field of the convection heat transfer is the widest and it is studied by the most people. We often encounter difficulties with the heat transfer strengthen in flow over tube or rod banks in various shell-and-tube heat exchangers, nuclear reactors and chemical reactors. The tube heat exchangers are widely used in practice because of simple manufacture and installation. But the flow characteristics and heat transfer mechanism of fluid through tube banks are not fully understood and there are many thorny issues to resolve.The paper, based on the existing theories, aims to discuss the convection heat transfer characteristics under different tube bank arrangements and relative distance between tubes by pure water flow over bare tube banks with the bare tube banks composed of stainless steel as the study object and with the pure water as the working substance.Under the existing conditions, the simulation experiment is made for the convection heat transfer in fluid flow over bare tube banks. The tube banks are heated by electricity. The experimental phenomena is observed and analyzed under certain Reynolds number. A preliminary study for the heat transfer mechanism is conducted on basis of the existing mature theoretical foundation. The convection heat transfer characteristics curve is fitted with the sufficient experimental data. The main factors and characteristics of the tube bank heat transfer are determined by the analysis of the final results.The experimental results show that, no matter the in-line or staggered tube banks, the heat transfer coefficient decreases with the increase of the longitudinal and transverse relative tube distance in the experimental range without other variable factors. Although the heat transfer weakens, the law of decrease is not very clear. Meanwhile, in the tube bank heat transfer, the staggered tube arrangements have certain advantages over the in-line tube arrangements under the same conditions.