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The enhancement of heat transfer in shell and tube heat exchangers with twisted -tape

DOI: 10.1615/ICHMT.2004.IntThermSciSemin.1260
pages 989-992

Viorel Iacob
SNP PETROM,INCERP-Cercetare Subsidiary, B-dul Republicii No.291A, Ploiesti-Romania

Dan C. Popescu
SNP PETROM, INCERP-Cercetare Subsidiary, B-dul Republicii No.291A, Ploiesti-Romania

Gh. Constantinescu
SNP-PETROM, Calea Victoriei No.109, Bucuresti-Romania

I. Ursache
RUPS - Brazi, Romania

Abstract

The performances of heat transfer equipment have capital influence on the process or industrial plants. Technical studies regarding the enhancement of heat transfer are focused on new methods and the extension of existing ones, as well. The practical results of these studies, justified both technical and economical, lead to the reduction of investment cost, better management and the enhancement of working indicators. Among the practical methods to increase the performances of heat transfer equipment, the using of turbulence promoters seems to be the most important.
With the help of turbulence promoters there is the possibility to create a local turbulence, which increases the heat transfer convection coefficients, but with the increase of energy necessary to move the fluids. The turbulence intensity at boundary level only can by realize through uniform or discreet modifications of aspect a heat transfer surfaces. This modality of action is specific to turbulence promoters "artificial roughness" type which can by granular, thread, groove, rings, ribs, etc. types.
The turbulence intensification in the whole mass of moving fluid can by realized in various manner and is specific for mass turbulence promoters. Because of important mass of fluids involved, these devices had utility for mixing, but most interesting applications are in the heat transfer or both the heat and mass transfer. Because their specific action, this category of turbulence promoters are named turbulence generators.
The practical use of turbulence promoters in industrial applications depend on many elements, which can favor one or other from existing constructive types. Because of the processing petroleum industry specific, which process and move the fluids with high viscosity, foulness and impurities, this last category of turbulence promoters become very attractive.
The work presented an experimental analysis a heat transfer through cylindrical horizontal tube having tree type of the turbulence generators. It have been used helix type turbulence generators with six propeller twisting of 45° and tape − twisted platbands.
The performances of turbulence promoters were estimated using an indicator for relative increase of convective factors over a relative increase of friction factors. Thus we selected the type of turbulence generators suitable in industrial applications from petroleum industry.
We presented also the results of an industrial experiment with a selected turbulence generator.

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