Experimental investigation on the convective heat transfer enhancement in tubes with cross-helix profile wall corrugation

34th UIT Heat Transfer Conference 2016

Cattani, L.^2 ; Bozzoli, F.^1,2 ; Rainieri, S.^1,2 ; Pagliarini, G.^1,2

Department of Industrial Engineering, University of Parma, Parco Area delle Scienze 181/A, Parma

I-43124, Italy^1

SITEIA.PARMA Interdepartmental Centre, University of Parma, Parco Area delle Scienze 181/A, Parma

I-43124, Italy^2

关键词: Convective heat transfer;    Corrugation pitches;    Experimental investigations;    Heat Transfer enhancement;    Helical corrugation;    Passive technique;    Smooth tubes;    Thermal Performance;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/796/1/012010/pdf
DOI  :  10.1088/1742-6596/796/1/012010

来源: IOP

【 摘 要 】

Wall corrugation is a popular heat transfer enhancement technique since it acts as a disturbance source in the flow that significantly enhances the thermal performance of the tube section with a limited pressure drop augmentation if compared to other passive techniques, such as the ones based on insert devices. In the hereby presented study nine pipes characterised by a cross-helix type corrugation were tested: this kind of corrugation, that was obtained by rolling twice the same tube with two helical corrugations evolving along opposite directions, showed a performance that exceeded the single helix-type corrugation behaviour and moreover presented an earlier transition to unstable regime. In the analysis the effect of the cross-helix type corrugation profile on the forced convection heat transfer mechanism was experimentally investigated in the Reynolds and Prandtl number range 25÷1000 and 115÷150 respectively. In particular, the effect of both the corrugation depth and the corrugation pitch were analysed. The results were compared with other types of wall corrugation and with the predictions for the smooth tube in order to point out the achieved heat transfer enhancement.