Thermal performance in a tubular heat exchanger with deltawinglets

Pattarapan Tongyote,Pongjet Promvonge,Withada Jedsadaratanachai,Nattawoot Depaiwa,C Hamontree

doi:10.1051/matecconf/201819202062

Pattarapan Tongyote, Pongjet Promvonge + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/201819202062

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Abstract

The paper presents an experimental heat transfer enhancement study in a tubular heat exchanger fitted with delta-winglets. The experimental work was conducted by varying the airflow rate in the test tube having a constant wall heat-flux for turbulent regime, Reynolds number (Re) from 5200 to 23,000. Effects of three pitch ratios (PR=P/D=1.5, 2.0 and 3.0) and two attack angles, α = 45° and 60°, of the winglets at a single blockage ratio (BR=b/D = 0.15) on thermal characteristics are examined. The experimental results show that the winglet-inserted tube yields, respectively, the heat transfer, friction factor and thermal performance in the form of TEF around 1.99–4.08, 4.9–14.3 times higher than the plain tube and 0.85–1.85, depending on the operating condition.

Highlights

Vortex flows have been extensively applied in thermal systems to increase their performance of such systems in industrial applications, for example, vortex tube [1], solar air heater [2,3], heat exchanger systems [4,5], etc
Vortex devices such as rib/baffle [6,7], coiled-wire [8,9], conical nozzles [10 13], twisted tape [14,15,16], fined tape [17,18], and winglet [19,20,21] are commonly employed for heat transfer enhancement in heating or cooling passages
The vortex generators (VGs) usually are inserted into the flow field to provide an interruption of boundary layer development and to accelerate the flow velocity, especially for tangential velocity, leading to increasing more turbulence intensity and causing the enhancement of the heat transfer rate

Summary

Introduction

Vortex flows have been extensively applied in thermal systems to increase their performance of such systems in industrial applications, for example, vortex tube [1], solar air heater [2,3], heat exchanger systems [4,5], etc Vortex devices such as rib/baffle [6,7], coiled-wire [8,9], conical nozzles [10 13], twisted tape [14,15,16], fined tape [17,18], and winglet [19,20,21] are commonly employed for heat transfer enhancement in heating or cooling passages. The experimental results using air as the test fluid are presented for turbulent flow, Reynolds number ranging from 5200 to 23,000 in the current study

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