Heat Transfer Enhancement by Using Different Types of Inserts

Heat transfer enhancement has been always a significantly interesting topic in order to develop high efficient, low cost, light weight, and small heat exchangers. The energy cost and environmental issue are also encouraging researchers to achieve better performance than the existing designs. Two of the most effective ways to achieve higher heat transfer rate in heat exchangers are using different kinds of inserts and modifying the heat exchanger tubes. There are different kinds of inserts employed in the heat exchanger tubes such as helical/twisted tapes, coiled wires, ribs/fins/baffles, and winglets. This paper presents an overview about the early studies on the improvement of the performance of thermal systems by using different kinds of inserts. Louvered strip insert had better function in backward flow compared to forward one. Modifying the shape of twisted tapes led to a higher efficiency in most of the cases excpet for perforated twisted tape and notched twisted tape. Combination of various inserts and tube with artificial roughness provided promising results. In case of using various propeller types, heat transfer enhancement was dependent on higher number of blades and blade angle and lower pitch ratio.

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Heat transfer enhancement in a parallel, finless heat exchanger using a longitudinal vortex generator, Part B: Experimental investigation on the performance of finless and fin-tube heat exchangers

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2018.06.048 ◽

2019 ◽

Vol 128 ◽

pp. 66-75 ◽

Cited By ~ 5

Author(s):

Jiyang Li ◽

Chaobin Dang ◽

Eiji Hihara

Keyword(s):

Heat Transfer ◽

Experimental Investigation ◽

Heat Exchanger ◽

Heat Transfer Enhancement ◽

Heat Exchangers ◽

Vortex Generator ◽

Longitudinal Vortex ◽

Transfer Enhancement ◽

Fin Tube

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Numerical Investigation of Heat Transfer Enhancement Using Hybrid Vortex Generator Arrays in Fin-and-Tube Heat Exchangers

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4033213 ◽

2016 ◽

Vol 8 (3) ◽

Cited By ~ 4

Author(s):

Shubham Agarwal ◽

R. P. Sharma

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Heat Transfer Enhancement ◽

Heat Exchangers ◽

Numerical Study ◽

Vortex Generator ◽

Roll Angle ◽

Transfer Enhancement ◽

Maximum Heat ◽

Hybrid Configuration

This is a novel study for assessing the heat transfer enhancement in a multi-row inline-tube heat exchanger using hybrid vortex generator (VG) arrays, i.e., rectangular winglet pairs (RWPs) with different geometrical configurations installed in coherence for enhanced heat transfer. The three-dimensional numerical study uses a full scale seven-tube inline heat exchanger model. The effect of roll of rectangular winglet VG on heat transfer enhancement is analyzed and optimized roll angle is determined for maximum heat transfer enhancement. Four different configurations are analyzed and compared in this regard: (a) single RWP (no roll); (b) 3RWP-inline array(alternating tube row with no roll of VGs); (c) single RWP (with optimized roll angle VGs); and (d) 3RWP-inline array(alternating tube row with all VGs having optimized roll angle). It was found that the inward roll of VGs increased the heat transfer from the immediately downstream tube but reduced heat transfer enhancement capability of other VG pairs downstream. Further, four different hybrid configurations of VGs were analyzed and the optimum configuration was obtained. For the optimized hybrid configuration at Re = 670, RWP with optimized roll angle increased heat transfer by 17.5% from the tube it was installed on and by 42% from the immediately downstream tube. Increase in j/ƒ of 36.7% is obtained by use of hybrid VGs in the optimized hybrid configuration. The deductions from the current study are supposed to well enhance the performance of heat exchangers with different design configurations.

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