Numerical evaluation and the effects of geometrical and operational parameters on thermal performance of the shell and double coil tube heat exchanger
01 Dec 2020-Vol. 49, Iss: 8, pp 4678-4703
About: The article was published on 2020-12-01. It has received 17 citations till now. The article focuses on the topics: Shell and tube heat exchanger & Heat transfer.
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TL;DR: In this paper, the authors evaluated the impact of the type of working fluid (two various hybrid nanofluids in comparison with pure water at the Reynolds number between 4125 and 5363) on the turbulence thermal performance of a pipe equipped with vortex generator.
Abstract: In the present work, hybrid nanofluids flow and heat transfer in a pipe equipped with vortex generator are evaluated numerically. At the first part, the impact of the type of working fluid (two various hybrid nanofluids in comparison with pure water at φ = 3%) and at the second part, impact of the volume concentration of selected hybrid nanofluid (based on section one) on the turbulence thermal performance of the pipe with innovative vortex generator are evaluated numerically. All the simulations were performed for the Reynolds number range between 4125 and 5363. The considered hybrid nanofluids include silver (Ag) and graphene (HEG) nanoparticles/water and MWCNT–Fe3O4/water. The proposed vortex generator has 18 blades to create secondary flows. Also, five output ports are considered at the conical part of vortex generator (four side outputs and one axial one). Results indicated that using both two techniques of heat transfer enhancement in a pipe including proposed vortex generator and hybrid nanofluids leads to higher heat transfer rate. As a result, the MWCNT–Fe3O4/water hybrid nanofluid has better thermal performance in all studied Reynolds number. At low Reynolds number (Re = 4125), the maximum thermal performance was achieved at φ = 1% by 11.3% growth in thermal performance. Also, case with φ = 5% has a minimum improvement, 10.5%. Furthermore, at high Reynolds number (Re = 5363), the highest and lowest growths belong to cases φ = 3% and φ = 7% by 9.9 and 7% improvement in thermal performance, respectively.
43 citations
TL;DR: In this paper, heat transfer and fluid flow in a corrugate coil tube with different lobe-shaped cross-sections are evaluated numerically, and spiral twisted tape is placed as turbulator with various geometries.
Abstract: In the present study, heat transfer and fluid flow in a corrugate coil tube with different lobe-shaped cross-sections are evaluated numerically. Also, spiral twisted tape as turbulator with various geometries is placed in the proposed corrugate coil tube. The examined parameters include the geometry of corrugated coil’s cross-section and twisted tape’s geometry in corrugated coil tube. Obtained results show that five-lobe cross-section rises the Nusselt number and pressure drop by 9.1% and 3.7%, respectively, in comparison with three-lobe case. Furthermore, increasing the area of spiral twisted tape in the five-lobe corrugated tube leads to growth in Nusselt number and pressure drop by 30.7% and 37.1%, respectively. Also, among the cases with spiral center cleared twisted tape, at higher investigated Reynolds number (Re = 35,000), the thermal efficiency of the three-, four-, and five-lobe models with center cleared twisted tape is more than the three-, four-, and five-lobe models with simple spiral twisted tape by 16, 18.64, and 19.16%, respectively.
34 citations
TL;DR: In this article, a numerical study of fluid flow and heat transfer in a solar parabolic trough collector containing turbulence-inducing elements on wall of collector has been performed, and the results indicated that at VInlet = 0.32 m/sec, thermal efficiencies of models with two to six number of elements are greater than plain PTC by 6.6, 13.2, 20.6 and 27.6%, respectively.
34 citations
TL;DR: In this article, the authors numerically examine the thermal performance of a round tubular heat exchanger featuring a combination of three passive techniques for heat transfer enhancement: (i) center-cleared twisted-tape, (ii) center cleared twisted tape, and (iii) twisted taping.
Abstract: We numerically examine the thermal performance of a round tubular heat exchanger featuring a combination of three passive techniques for heat-transfer enhancement: (i) center-cleared twisted-tape i...
24 citations
TL;DR: In this paper, a numerical investigation is presented on heat transfer augmenting by using various kinds of modified multiple twisted tape inserted in solar parabolic trough collectors, where the received heat flux on the solar absorber was assumed non-uniform due to hemispheric insolation of sun.
Abstract: In this paper, a numerical investigation is presented on heat transfer augmenting by using various kinds of modified multiple twisted tape inserted in solar parabolic trough collectors. The pressurized water is considered as working fluid and Reynolds number varying from 10000 to 20000. The received heat flux on the solar absorber was assumed non-uniform due to hemispheric insolation of sun. The obtained numerical results for the Nusselt number, friction factor and thermal performance are presented for each cases. Various types of twisted tape including single twisted tape, normal, perforated, center-cleared, square, and V-cut dual twisted tape are considered and analyzed. The numerical simulations are performed by a commercial CFD code, ANSYS FLUENT 18.2. The obtained results revealed that at Re=10000 and 20000, the average Nusselt numbers of case with dual v-cut twisted tapes are more than plaine tube by 19.58 and 17.44%, respectively. Moreover, thermal performance of all cases with various twisted tapes is larger than 1 which means that utilizing twisted tape with various configurations leads to more thermal performance than plain tube. The thermal performances of case with dual square-cut twisted tapes (as the best case) for Re=10000 and 20000 are more than plain tube by about 16 and 12% improvement, respectively. Furthermore, for the case with perforated dual twisted tape (as the case with lowest thermal performance), the thermal performances for Re=10000 and 20000 are more than plain tube by about 9.2 and 7% improvement, respectively.
18 citations
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...Finally, thermal performance is calculated using [54-59]:...
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References
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532 citations
302 citations
TL;DR: The variation of local Nusselt number along the length and circumference at the wall of a helical pipe is brought out and a correlation to predict the local values of Nusselst number as a function of angular location of the point is presented.
213 citations
TL;DR: In this article, the heat transfer coefficients of shell and helically coiled tube heat exchangers were investigated experimentally, and the calculated heat transfer coefficient of tube-side were also compared to the existing correlations for other boundary conditions and a reasonable agreement was observed.
186 citations
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...j j j eff eff h ∑ ∂ ∂ ∇ ⋅ → ∇ ∇ → ⋅→ (3)...
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