Turbulent forced convection in a heat exchanger square channel with wavy-ribs vortex generator

doi:10.1016/j.cjche.2015.04.001

Abstract

Abstract: Turbulent forced convective heat transfer and flow configurations in a square channel with wavy-ribs inserted diagonally are examined numerically. The influences of the 30° and 45° flowattack angles forwavy-ribs, blockage ratio, R_B=b/H=0.05-0.25with single pitch ratio, R_P=P/H=1 are investigated for the Reynolds number based on the hydraulic diameter of the square channel, Re=3000-20000. The use of the wavy-ribs, which inserted diagonal in the square channel, is aimed to help to improve the thermal performance in heat exchange systems. The finite volume method and SIMPLE algorithm are applied to the present numerical simulation. The results are presented on the periodic flow and heat transfer profiles, flow configurations, heat transfer characteristics and the performance evaluations. The mathematical results reveal that the use of wavy-ribs leads to a higher heat transfer rate and friction loss over the smooth channel. The heat transfer enhancements are around 1.97-5.14 and 2.04-5.27 times over the smooth channel for 30° and 45° attack angles, respectively. However, the corresponding friction loss values for 30° and 45° are around 4.26-86.55 and 5.03-97.98 times higher than the smooth square channel, respectively. The optimumthermal enhancement factor on both cases is found at R_B=0.10 and the lowest Reynolds number, Re=3000, to be about 1.47 and 1.52, respectively, for 30° and 45° wavy-ribs.

Key words: Flow configuration, Forced convection, Heat transfer characteristic, Turbulent flow, Wavy-ribs

摘要： Turbulent forced convective heat transfer and flow configurations in a square channel with wavy-ribs inserted diagonally are examined numerically. The influences of the 30° and 45° flowattack angles forwavy-ribs, blockage ratio, R_B=b/H=0.05-0.25with single pitch ratio, R_P=P/H=1 are investigated for the Reynolds number based on the hydraulic diameter of the square channel, Re=3000-20000. The use of the wavy-ribs, which inserted diagonal in the square channel, is aimed to help to improve the thermal performance in heat exchange systems. The finite volume method and SIMPLE algorithm are applied to the present numerical simulation. The results are presented on the periodic flow and heat transfer profiles, flow configurations, heat transfer characteristics and the performance evaluations. The mathematical results reveal that the use of wavy-ribs leads to a higher heat transfer rate and friction loss over the smooth channel. The heat transfer enhancements are around 1.97-5.14 and 2.04-5.27 times over the smooth channel for 30° and 45° attack angles, respectively. However, the corresponding friction loss values for 30° and 45° are around 4.26-86.55 and 5.03-97.98 times higher than the smooth square channel, respectively. The optimumthermal enhancement factor on both cases is found at R_B=0.10 and the lowest Reynolds number, Re=3000, to be about 1.47 and 1.52, respectively, for 30° and 45° wavy-ribs.

关键词: Flow configuration, Forced convection, Heat transfer characteristic, Turbulent flow, Wavy-ribs

Amnart Boonloi, Withada Jedsadaratanachai. Turbulent forced convection in a heat exchanger square channel with wavy-ribs vortex generator[J]. Chin.J.Chem.Eng., 2015, 23(8): 1256-1265.

Amnart Boonloi, Withada Jedsadaratanachai. Turbulent forced convection in a heat exchanger square channel with wavy-ribs vortex generator[J]. Chinese Journal of Chemical Engineering, 2015, 23(8): 1256-1265.

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