Heat Transfer and Flow Structures Around Circular Cylinders in Cross-Flow


Abstract: An experimental study was carried out to investigate heat transfer and flow characteristics from one tube within a staggered tube bundle and within a row of similar tubes. The tube spacing examined S_t and S_l are 1.5\times1.5 and 1.5\times1.25 where S_l and S_t denote the longitudinal and transverse pitches respectively. The variation of local Nusselt number was predicted with Reynolds number 4.8\times 10^4. The aim of the second part of the investigation was to examined the influence of the blockage of a single tube in a duct and transverse pitch for a single tube row with Reynolds number range of 7960 to 47770. Blockage ratio was varied from 0.131 to 0.843. Variation of local Nusselt number and local pressure coefficient were shown with different blockages and Reynolds numbers. The main results are described below. For single tube row experiments, if the blockage ratio is less than 0.5, the general shape of local Nusselt number distribution around the cylinder varies only slightly with blockage. However the local Nusselt number and pressure coefficient distributions are remarkably different for the blockage ratio in the range of 0.668-0.843. Tube bundle experiments showed that changing longitudinal ratio did not affect the mean Nusselt number.

Keywords: Heat Exchangers, Effect of Blockage, Cross-flow, Tube Bundle

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