Comparison and validation of turbulence models in the numerical study of heat exchangers

Marín, Juan Gonzalo Ardila; Zuluaga, Diego Andrés Hincapié; Monroy, Julio Alberto Casas

doi:10.18180/tecciencia.2015.19.8

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…The calculation of the Stratification Number represented as St, involves the division of the time scale for thermal diffusion by the time scale for turnover. The thermal diffusion time scale pertains to the duration necessary for the propagation of thermal energy throughout the tank, whereas the turnover time scale denotes the duration required for a full volume turnover of the tank [32], [33]. An increased value of the Stratification Number (St) signifies a heightened thermal stratification, characterized by distinct layers of hot and cold water.…”

Section: Stratification Numbermentioning

confidence: 99%

Thermal Stratification in Solar Water Storage Tanks through Inlet Port Diffuser Optimization during Charge and Discharge Processes

Barrak,

Hammodi,

Mouthanna

2024

Engineering Headway

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The enhancement of thermal stratification in solar storage tanks is a crucial aspect of advancing solar energy technology. This study presents an experimental investigation conducted on a vertical cylindrical hot solar water storage tank operating in a dynamic mode, involving simultaneous charging and discharging. The experiment aims to assess the impact of varying inlet water flow rates (4, 6, 8, 10 L/min) on thermal stratification within the tank and explores strategies to mitigate heat losses to the environment and minimize mixing effects caused by the inlet fluid flow. The experimental setup incorporates insulation and an inlet port diffuser section to optimize the distribution of inlet water during the charging and discharging states. The results reveal that the utilization of an inlet port diffuser significantly improves thermal stratification by reducing heat losses and minimizing mixing effects, as evidenced by improved Richardson numbers. Additionally, this study contributes to the development of a compact solar domestic hot water (SDHW) solution.

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Section: Stratification Numbermentioning

confidence: 99%

Thermal Stratification in Solar Water Storage Tanks through Inlet Port Diffuser Optimization during Charge and Discharge Processes

Barrak,

Hammodi,

Mouthanna

2024

Engineering Headway

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“…b) Two-turn helical corrugation, adapted from[8]. c) One-and four-inlet helical tubes, adapted from[51].…”

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confidence: 99%

Heat exchangers with double passive enhancement

Valdes¹,

Marín²

2018

ces

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The use of passive enhancement for heat exchangers, as well as the interest of the academic community in its study, has increased. It has been found that the improvement of the transfer rate is the result of the formation of secondary flows, the increase in turbulence or, simply, the increase in transfer area. In general terms, when the contact between more particles and the transfer surface is enabled during the passage through the tubes, heat transfer increases. As a result, a great deal of studies is available, and a series of heat transfer correlations has been proposed. Such correlations have been numerically or experimentally developed, and enable to predict the convection and estimate the size of the exchangers, which makes them a fundamental design tool. This article is a review of the most important studies recently published in this field. It presents the geometries that provide single and double passive enhancements and some of the correlations that are applied to heat exchangers with double passive enhancement. In brief, this work constitutes a thorough review of the results of numerical and/or experimental research-as well as other reviews-in the field of heat exchangers in which the transfer phenomenon has been improved by means of passive techniques.

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A new three-dimensional CFD model for efficiency optimisation of fluid-to-air multi-fin heat exchanger

Altwieb

Kubiak

Aliyu

et al. 2020

Thermal Science and Engineering Progress

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New simulation and experimental results have been obtained and are presented for a multi-tube fin heat exchanger unit, from which semi-analytical correlations for the Fanning friction and Colburn factors were developed. The multi-tube and fin heat exchanger represents the main component of the Fan Coil Unit, an essential component of HVAC systems used for domestic and commercial heating and cooling. Improving the efficiency of the heat exchanger typically comes at the expense of higher pressure drops or costlier materials and production costs. Here, an experimental setup was designed and constructed to evaluate the thermal performance of such a heat exchanger. Geometrical modifications were explored for thermal performance enhancement. Furthermore, full three-dimensional CFD case studies of the heat exchanger were investigated to examine the effect of the geometrical features on the air side of the heat exchanger to study the effect of fin spacing, transverse and longitudinal pitches. The CFD model developed was first globally validated against experimental results. The model results were used to predict the Fanning and Colburn factors and the local fin efficiency based on the carefully selected geometric parameters. The data obtained was utilised to develop two new semi-analytical models for the Fanning and Colburn friction factors which were well within ±10% error bands and showed strong correlation coefficients of more than 98 and 97% respectively.

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Comparison and validation of turbulence models in the numerical study of heat exchangers

Cited by 5 publications

References 14 publications

Thermal Stratification in Solar Water Storage Tanks through Inlet Port Diffuser Optimization during Charge and Discharge Processes

Thermal Stratification in Solar Water Storage Tanks through Inlet Port Diffuser Optimization during Charge and Discharge Processes

Heat exchangers with double passive enhancement

A new three-dimensional CFD model for efficiency optimisation of fluid-to-air multi-fin heat exchanger

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