Experimental heat transfer investigations of a double pipe U-tube heat exchanger equipped with twisted tape and cut twisted tape internals

This study investigated the laminar convective heat transfer and fluid flow of Al2O3 nanofluid in a counter flow double-pipe heat exchanger equipped with overlapped twisted tape inserts in both inner and outer tubes. Two models of the same (co-swirling twisted tapes) and opposite (counter-swirling twisted tapes) angular directions for the stationary twisted tapes were considered. The computational fluid dynamic simulations were conducted through varying the design parameters, including the angular direction of twisted tape inserts, nanofluid volume concentration, and Reynolds number. It was found that inserting the overlapped twisted tapes in the heat exchanger significantly increases the thermal performance as well as the friction factor compared with the plain heat exchanger. The results indicate that models of co-swirling twisted tapes and counter-swirling twisted tapes increase the average Nusselt number by almost 35.2–66.2% and 42.1–68.7% over the Reynolds number ranging 250–1000, respectively. To assess the interplay between heat transfer enhancement and pressure loss penalty, the dimensionless number of performance evaluation criterion was calculated for all the captured configurations. Ultimately, the highest value of performance evaluation criterion is equal to 1.40 and 1.26 at inner and outer tubes at the Reynolds number of 1000 and the volume fraction of 3% in the case of counter-swirling twisted tapes model.

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Experimental Study of Turbulent Flow Heat Transfer and Pressure Drop in a Plate Heat Exchanger With Chevron Plates

Journal of Heat Transfer ◽

10.1115/1.2825923 ◽

1999 ◽

Vol 121 (1) ◽

pp. 110-117 ◽

Cited By ~ 180

Author(s):

A. Muley ◽

R. M. Manglik

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Pressure Drop ◽

Flat Plate ◽

Plate Heat Exchanger ◽

Plate Heat ◽

Experimental Heat ◽

Experimental Heat Transfer ◽

Flow Heat ◽

Phase Water

Experimental heat transfer and isothermal pressure drop data for single-phase water flows in a plate heat exchanger (PHE) with chevron plates are presented. In a single-pass U-type counterflow PHE, three different chevron plate arrangements are considered: two symmetric plate arrangements with β = 30 deg/30 deg and 60 deg/60 deg, and one mixed-plate arrangement with β = 30 deg/60 deg. For water (2 < Pr < 6) flow rates in the 600 < Re < 104 regime, data for Nu and f are presented. The results show significant effects of both the chevron angle β and surface area enlargement factor φ. As β increases, and compared to a flat-plate pack, up to two to five times higher Nu are obtained; the concomitant f, however, are 13 to 44 times higher. Increasing φ also has a similar, though smaller effect. Based on experimental data for Re a 7000 and 30 deg ≤ β ≤ 60 deg, predictive correlations of the form Nu = C1,(β) D1(φ) Rep1(β)Pr1/3(μ/μw)0.14 and f = C2(β) D2(φ) Rep2(β) are devised. Finally, at constant pumping power, and depending upon Re, β, and φ, the heat transfer is found to be enhanced by up to 2.8 times that in an equivalent flat-plate channel.

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