Development of a new type of finned heat exchanger

Bošnjaković, Mladen; Čikić, Ante; Muhič, Simon; Stojkov, Marinko

doi:10.17559/tv-20171011071711

Cited by 11 publications

(24 citation statements)

References 16 publications

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“…The initial geometry is defined in [21,22]. Star-shaped fins, 0.5 mm thick with an outside diameter of 40 mm, were attached to the tube Ø20 as the reference geometry.…”

Section: The Geometry Descriptionmentioning

confidence: 99%

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Numerical Analysis of Tube Heat Exchanger with Perforated Star-Shaped Fins

Bošnjaković

Muhič²

2020

Fluids

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This article discusses the possibility of further reducing the mass of the heat exchanger with stainless steel star-shaped fins while achieving good heat transfer performance. For this purpose, we perforated the fins with holes Ø2, Ø3, and Ø4 mm. Applying computational fluid dynamics (CFD) numerical analysis, we determined the influence of each perforation on the characteristics of the flow field in the liquid–gas type of heat exchanger and the heat transfer for the range of Re numbers from 2300 to 16,000. With a reduction in the mass of the fins to 17.65% (by Ø4 mm), perforated fins had greater heat transfer from 5.5% to 11.3% than fins without perforation. A comparison of perforated star-shaped fins with annular fins was also performed. Perforated fins had 51.8% less mass than annular fins, with an increase in heat transfer up to 26.5% in terms of Nusselt number.

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“…The initial geometry is defined in [21,22]. Star-shaped fins, 0.5 mm thick with an outside diameter of 40 mm, were attached to the tube Ø20 as the reference geometry.…”

Section: The Geometry Descriptionmentioning

confidence: 99%

“…One of the proposals to reduce the heat exchangers mass with enhancement in the heat transfer is to apply star-shaped fins [21][22][23]. The authors constructed tubular heat exchangers with star-shaped fins and analyzed them by CFD simulation.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Tube Heat Exchanger with Perforated Star-Shaped Fins

Bošnjaković

Muhič²

2020

Fluids

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“…The final mesh, which gives results independent of the numeric mesh consists of approximately 11 million control volumes, where dimensionless wall distance y+ < 1 (Figures 5-7). Details related to the convergence criteria, numerical simulation parameters and the validation of results obtained are presented in [20]. The boundary conditions were defined according to Table 3.…”

Section: Numerical Analysismentioning

confidence: 99%

“…This influence was numerically analysed by setting five values of thermal conductivity (16 W/(mK), 160 W/(mK), 1600 W/(mK), 16,000W/(mK), 160,000 W/(mK)) at an air velocity of 5 m/s (Re = 11,218). Details related to the convergence criteria, numerical simulation parameters and the validation of results obtained are presented in [20]. The boundary conditions were defined according to Table 3.…”

Section: Numerical Analysismentioning

confidence: 99%

How Big Is an Error in the Analytical Calculation of Annular Fin Efficiency?

Bošnjaković

Muhič²,

Čikić

et al. 2019

Energies

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An important role in the dimensioning of heat exchange surfaces with an annular fin is the fin efficiency. The fin efficiency is usually calculated using analytical expressions developed in the last century. However, these expressions are derived with certain assumptions and simplifications that involve a certain error in the calculation. The purpose of this paper is to determine the size of the error due to the assumptions and simplifications made when performing the analytical expression and to present what has the greatest impact on the amount of error, and give a recommendation on how to reduce that error. In order to determine the error, but also to gain a more detailed insight into the physics of heat exchange processes on the fin surface, computational fluid dynamics was applied to the original definition of fin efficiency. This means that a numerical simulation was performed for the actual fin material and for the ideal fin material with infinite thermal conductivity for the selected fin geometry and Re numbers from 2000 to 18,000. The results show that fin efficiency determined by numerical simulations is greater by up to 12.3% than the efficiency calculated analytically. The greatest impact on the amount of error is the assumption of the same temperature of the fin base surface and the outer tube surface and the assumption of equal heat transfer coefficient on the entire fin surface area. Using a newly recommended expression for the equivalent length of the fin tip, it would be possible to calculate the fin efficiency more precisely and thus the average heat transfer coefficient on the fin surface area, which leads to a more accurate dimensioning of the heat exchanger.

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“…To solve this problem, microfluidic systems are used, produced, in particular, by stamped way with miniature heatconducting channels. Since the total calculated diameter of intermediate heat exchangers in horizontal areas in practice does not exceed 50 mm, then the diameters of multi-channel heat exchangers of the "pipe-in-pipe" type can be reduced to tens-hundreds of micrometres with the use of exclusively microfluidic technologies [18].…”

Section: Introductionmentioning

confidence: 99%

Improving the geometric topology of geothermal heat exchangers in oil bore-holes

et al. 2019

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A review has been conducted of key trends in the development of geometric topology of geothermal heat exchangers. Authors proposed approaches to improving the designs and network structures for heat-transfer media circulation in the bottom-hole space of oil-and-gas reservoirs. Four geometric topologies of geothermal heat exchangers have been analysed: І – ІІ – rectilinear vertical smooth and finned pipelines; ІІІ – IV – a cluster in the form of a set of smooth and finned single-pipe elements, representing a figure of “squirrel wheel” or “meridian sphere” type. It is shown that the most effective technical solution, which ensures the increase in the coefficient of performance (COP) of bore-hole geothermal systems is finning the heat exchanging pipes. For the heat exchangers of І – ІІ type, the calculated increase in COP in comparison with smooth pipes is 40%, and for ІІІ – IV type – 95%. The key parameters influencing the COP of a geothermal heat exchanger are: the radius of fluids draining out during the heat exchange process, the radius of pipelines with circulating heat-transfer medium, the diameter of a cluster heat exchanger, the heat exchange area, the parameters of rocks thermal resistance in the bottom-hole zone of heat-receiving.

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Development of a new type of finned heat exchanger

Cited by 11 publications

References 16 publications

Numerical Analysis of Tube Heat Exchanger with Perforated Star-Shaped Fins

Numerical Analysis of Tube Heat Exchanger with Perforated Star-Shaped Fins

How Big Is an Error in the Analytical Calculation of Annular Fin Efficiency?

Improving the geometric topology of geothermal heat exchangers in oil bore-holes

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