Study on characteristics of fluid-flow and heat transfer in the torsional flow heat exchanger with drop-shaped tube

Wang, Yongqing; Zhang, Qianxin; Wang, Guan; Li, Ning; Chen, Cheng; Gu, Xinjian

doi:10.2298/tsci210712297w

Cited by 2 publications

(1 citation statement)

References 29 publications

(38 reference statements)

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“…However, due to special conditions in the evaporator, the refrigerant/oil mixture remains in the evaporator There is the phenomenon of lubricant adhesion to the pipe wall [6]. In order to improve the heat exchange efficiency on this basis, the mathematicians studied the performance of the heat exchanger and the boiling heat exchange of the pipe [7][8]. Although this improves the evaporator heat exchange, but the oil layer caused by lubricant obstruction heat exchange problem has not been fundamentally resolved.…”

Section: Introductionmentioning

confidence: 99%

Low temperature simulation of ammonia refrigeration based on dissipative molecular dynamics

et al. 2023

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To solve the problem of heat resistance of the oil film in the evaporator pipeline of the ammonia refrigeration system, it is extremely important to study the interaction mechanism of the oil/ammonia system. The method of dissipative molecular dynamics is used to simulate the oil/ammonia flow state at different temperatures and concentrations, and the mechanism of its interaction was analyzed. It was also found that various parameters are greatly affected by temperature in the research process, the linear relationship of temperature on various parameters was quantitatively calculated. The oil/ammonia system were divided into emulsion and layered liquid. The oil phase (or ammonia phase) with low percentage at low temperature all exists in the form of droplets. The oil-ammonia interfacial tension first increases and then decreases with the increase of oil content. At the same temperature, the interfacial tension reached its maximum when the oil content was 70%. The oil percentage of 30% concentration was the phase inversion point. When the oil percentage was 30-70%, the oil and ammonia two phases were stratified, and the oil adhered to the surface of the pipe wall. Therefore, the heat transfer performance of the system was the worst when the oil content was 30-70%. As the temperature increased, the interaction parameter aij decreased significantly. The linear relationship between ? and 1/T was very consistent with the Flory-Huggins mean field theory. This linear equation provided a basis for subsequent related research.

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Section: Introductionmentioning

confidence: 99%

Low temperature simulation of ammonia refrigeration based on dissipative molecular dynamics

et al. 2023

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Performance and Structure Optimization of Torsional Flow Heat Exchanger With Orthogonal Drop-Shaped Tube

Gu,

Zhu,

Sun

et al. 2024

Heat Trans Res

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As a novel adaptation of shell-and-tube heat exchanger, the torsional flow heat exchanger holds promising application prospects. Drop-shaped tubes are employed to enhance fluid flow velocity, distribution, and overall heat transfer performance. This study presents a torsional flow heat exchanger featuring orthogonal drop-shaped tubes on the shell side, aiming to combine the advantages of both designs. Three numerical models of torsional flow heat exchangers are established with identical structures but varying axial ratios of the heat transfer tubes. The fluid flow and heat transfer characteristics on the shell side are analyzed numerically. The response surface method is utilized to optimize a shell-side structure. The results show that the torsional flow heat exchangers with orthogonal drop-shaped tubes of three axial ratios show reductions in pressure drop by 9.26-14.49%, increases in heat transfer coefficient by 0.65-11.57%, and improvements in comprehensive performance by 14.18-27.23% within the Reynolds number range from 5000 to 13,000, compared to those with common round tubes. The optimum structure of the torsional flow heat exchanger with orthogonal drop-shaped tubes is predicted using Minitab, resulting in a 17.19% improvement in the heat transfer coefficient and an 18.63% improvement in comprehensive performance. The study provides a reference for the exploration and improvement of torsional flow heat exchangers with enhanced tubes.

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Study on characteristics of fluid-flow and heat transfer in the torsional flow heat exchanger with drop-shaped tube

Cited by 2 publications

References 29 publications

Low temperature simulation of ammonia refrigeration based on dissipative molecular dynamics

Low temperature simulation of ammonia refrigeration based on dissipative molecular dynamics

Performance and Structure Optimization of Torsional Flow Heat Exchanger With Orthogonal Drop-Shaped Tube

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