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Добірка наукової літератури з теми "HTF TUBE WITH FINS"

Автор: Grafiati

Опубліковано: 11 вересня 2023

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Статті в журналах з теми "HTF TUBE WITH FINS"

Senthil, Ramalingam, Aditya Patel, Rohan Rao, and Sahil Ganeriwal. "Melting Behavior of Phase Change Material in a Solar Vertical Thermal Energy Storage with Variable Length Fins added on the Heat Transfer Tube Surfaces." International Journal of Renewable Energy Development 9, no. 3 (June 25, 2020): 361–67. http://dx.doi.org/10.14710/ijred.2020.29879.

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This paper investigates the melting behaviour of phase change material (PCM) in a vertical thermal energy storage system with provision of thin rectangular fins of uniform and variable lengths on the heat transfer tube surfaces. The selected PCM and heat transfer fluid (HTF) are paraffin wax and water, respectively. The HTF is passed through the helically coiled copper tube of 10 mm diameter to melt the PCM. The time required to complete the melting of PCM in the system with fins is found to be five hours, whereas for the system without fins it is five hours and forty minutes, for the same conditions of constant water temperature of about 70°C and flow rate of 0.02 kg/s. HTF tube with fins is observed to be more effective with a 13.33% faster rate of melting when compared to that of the HTF tube without fins. Such a fast charging process will be helpful in storing maximum energy within a short period/duration of time shorter duration in for solar thermal and heat recovery applications during lean production times. ©2020. CBIORE-IJRED. All rights reserved

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Senthil, Ramalingam. "Effect of uniform and variable fin height on charging and discharging of phase change material in a horizontal cylindrical thermal storage." Thermal Science 23, no. 3 Part B (2019): 1981–88. http://dx.doi.org/10.2298/tsci170709239s.

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Анотація:

The effect of fin profile on melting of phase change material (PCM) is presented. The test section contains an acrylic tube of 50 mm outer diameter and a copper tube of 16 mm outer diameter and a length of 1000 mm each. Both tubes are kept coaxially. The heat transfer fluid (HTF) flows through the copper tube. The PCM is paraffin wax and filled in the annular region. The considered fin profiles are the uniform and variable fin heights of circular, triangular and elliptical profiles. Fins are fixed on the HTF tube and protruded into the PCM. The total fin surface area is maintained same among the fin profiles and the fin arrangements. The one-third of the storage is provided with increasing fin height of 2- 3 mm to melt the settled solid PCM. The hot and cold water is used to charge and discharge the PCM, respectively. Experiments are performed by the hot and cold-water inlet temperatures of 70 ?C and 28 ?C at a flow rate of 0.5 kg per minute. A faster and effective heat transfer from HTF to PCM and vice-versa is investigated. The variable elliptical fins showed faster charging and discharging by 25% and 20%, respectively, than the variable circular fins. The variable elliptical fins showed faster charging and discharging by 11.8% and 11% than the variable triangular fins. The charging and discharging efficiency of 80% and 74% are observed for the elliptical fin profiles.

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Torbarina, Fran, Kristian Lenic, and Anica Trp. "Computational Model of Shell and Finned Tube Latent Thermal Energy Storage Developed as a New TRNSYS Type." Energies 15, no. 7 (March 25, 2022): 2434. http://dx.doi.org/10.3390/en15072434.

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This paper presents the development of a computational model of latent thermal energy storage (LTES) in a shell and tube configuration with longitudinal fins. The model describes the physical process of transient heat transfer between the heat transfer fluid (HTF) and the phase change material (PCM) in LTES. For modeling the phase change of the PCM, the enthalpy formulation was used. Based on a one-dimensional computational model, a new Trnsys type was developed and written in Fortran. Validation of the LTES model was performed by comparing numerically and experimentally obtained data for the melting and solidification of paraffin RT 25 as the PCM and water as the HTF. Numerical investigations of the effect of HTF inlet temperature and HTF flow rate on heat transfer in LTES confirmed that significant improvement in heat transfer between the HTF and PCM could be achieved by increasing the HTF inlet temperature during charging or decreasing the HTF inlet temperature during discharging. Increasing the HTF flow rate did not significantly improve the heat transfer between the HTF and PCM, both during charging and discharging. The presented, experimentally validated LTES model could be used to analyze the feasibility of integrating LTES into various thermal systems and ultimately help define the specific benefits of implementing LTES systems.

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Akarsh, A., and Sumer Dirbude. "Effect of HTF flow direction, mass flow rate and fins on melting and solidification in a latent-heat-based thermal energy storage device." Journal of Physics: Conference Series 2054, no. 1 (October 1, 2021): 012049. http://dx.doi.org/10.1088/1742-6596/2054/1/012049.

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Abstract Latent-heat-based thermal energy systems (LHTES) have commonly been used as a potential energy storage mode over any other mode of thermal energy storage. Many heat transfer enhancement techniques have been proposed over the past years. These techniques reduce the melting and solidification times. Most of these techniques focus on the phase change material (PCM). However, the flow direction of the heat transfer fluid (HTF) can affect the heat transfer performance and pumping power requirement of the system. In this paper, the effect of HTF-flow direction, HTF mass flow rate and addition of the fins on the melting and solidification of the PCM in a shell-and-tube type of energy storage is numerically studied. Two-dimensional transient simulations are performed with ANSYS-Fluent where the phase-change process is modelled using the enthalpy-porosity formulation. The model is verified and validated by comparing with the available experimental data. A reasonable match is observed. The validated model, is used to study the effects of various parameters, such as, mass flow rate of the HTF, and triangular fin (at a fixed fin pitch) for both charging and discharging of the PCM. Finally, an influence of flow direction on the melting and solidification time has been studied. It is found that the contribution of HTF mass flow rate, the addition of the fin and HTF flow directions respectively is 1.3-3.01%, 16.97-17.62%, and 1.3-1.77% of overall heat transfer performance. A major contribution to the enhancement of overall heat transfer of the system is from the addition of fins.

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Yu, Meng, Xiaowei Sun, Wenjuan Su, Defeng Li, Jun Shen, Xuejun Zhang, and Long Jiang. "Investigation on the Melting Performance of a Phase Change Material Based on a Shell-and-Tube Thermal Energy Storage Unit with a Rectangular Fin Configuration." Energies 15, no. 21 (November 3, 2022): 8200. http://dx.doi.org/10.3390/en15218200.

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Анотація:

A case study on the melting performance of a shell-and-tube phase change material (PCM) thermal energy storage unit with a novel rectangular fin configuration is conducted in this paper. Paraffin wax and circulated water are employed as the PCM and heat transfer fluid (HTF), respectively. It can be observed that the melting performance could be significantly improved by using rectangular fins. Melting photographs demonstrate that the melting of the PCM is firstly dominated by heat conduction; then, the melting rate is improved further due to natural convection. Moreover, the results illustrate that the influence of the inlet HTF temperature on the melting performance is significantly greater than that of the inlet HTF flow rate. The liquid fraction of paraffin wax in the PCM unit with a higher inlet HTF temperature is always higher than that with a lower inlet HTF temperature at the same time. The total charging time is reduced by 62.38% and the average charging rate is increased by 165.51% when the inlet HTF temperature is increased from 57 °C to 68 °C. As a result, a higher value of the inlet HTF temperature and a lower value of the HTF flow rate are able to improve the energy efficiency of the PCM unit with a rectangular fin configuration.

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Sun, Xinguo, Hayder I. Mohammed, Mohammadreza Ebrahimnataj Tiji, Jasim M. Mahdi, Hasan Sh Majdi, Zixiong Wang, Pouyan Talebizadehsardari, and Wahiba Yaïci. "Investigation of Heat Transfer Enhancement in a Triple Tube Latent Heat Storage System Using Circular Fins with Inline and Staggered Arrangements." Nanomaterials 11, no. 10 (October 9, 2021): 2647. http://dx.doi.org/10.3390/nano11102647.

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Анотація:

Inherent fluctuations in the availability of energy from renewables, particularly solar, remain a substantial impediment to their widespread deployment worldwide. Employing phase-change materials (PCMs) as media, saving energy for later consumption, offers a promising solution for overcoming the problem. However, the heat conductivities of most PCMs are limited, which severely limits the energy storage potential of these materials. This study suggests employing circular fins with staggered distribution to achieve improved thermal response rates of PCM in a vertical triple-tube heat exchanger involving two opposite flow streams of the heat-transfer fluid (HTF). Since heat diffusion is not the same at various portions of the PCM unit, different fin configurations, fin dimensions and HTF flow boundary conditions were explored using computational studies of melting in the PCM triple-tube system. Staggered configuration of fin distribution resulted in significant increases in the rates of PCM melting. The results indicate that the melting rate and heat charging rate could be increased by 37.2 and 59.1%, respectively, in the case of staggered distribution. Furthermore, the use of lengthy fins with smaller thickness in the vertical direction of the storage unit resulted in a better positive role of natural convection; thus, faster melting rates were achieved. With fin dimensions of 0.666 mm × 15 mm, the melting rate was found to be increased by 23.6%, when compared to the base case of 2 mm × 5 mm. Finally, it was confirmed that the values of the Reynolds number and inlet temperatures of the HTF had a significant impact on melting time savings when circular fins of staggered distribution were included.

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Cieśliński, Janusz T., and Maciej Fabrykiewicz. "Thermal Energy Storage with PCMs in Shell-and-Tube Units: A Review." Energies 16, no. 2 (January 13, 2023): 936. http://dx.doi.org/10.3390/en16020936.

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Анотація:

The paper presents a survey of the experimental and numerical studies of shell-and-tube systems in which phase change material (PCM) is used. Due to the multitude of design solutions for shell-and-tube systems, the emphasis is placed on double-tube (DT), triplex-tube (TT), and multi-tube (MT) units. Additionally, only single-pass systems are considered. Particular attention is paid to the method of heat transfer intensification. The analysis of the research results begins with the classification of each of the three mentioned systems. The systems are divided according to the angle of inclination, the method of heat transfer enhancement (HTE), the flow direction of heat transfer fluid (HTF), and the arrangement of tubes in the bundle. Moreover, the simplified schemes of the particular research cases are proposed. Then, the works on each of the mentioned systems, i.e., DT, TT, and MT, are discussed chronologically. Finally, in the corresponding tables, details of the discussed cases are presented, such as geometric dimensions, and the type of PCM or HTF used. A novelty in the present work is the precise classification of PCM TESUs as DT, TTH, and MTH. In the literature, there is a lot of discretion in this regard. Second, the methods of heat transfer intensification in the presented PCM TESUs are listed and discussed. Third, unified schemes of design solutions for the discussed PCM TESUs are proposed. The review shows that development directions for shell-and-tube TESUs include systems with high conductivity fins of different shapes, heights, and spacing, several PCMs, and modified shells.

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Pagkalos, Christos, Michalis Gr Vrachopoulos, John Konstantaras, and Kostas Lymperis. "Comparing water and paraffin PCM as storage mediums for thermal energy storage applications." E3S Web of Conferences 116 (2019): 00057. http://dx.doi.org/10.1051/e3sconf/201911600057.

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Анотація:

A CFD analysis is performed in two different heat storage mediums, water and paraffin phase change material (PCM), in order to evaluate and compare the two mediums for use in heating thermal energy storage (HTES) applications. The two mediums use different heat storing mechanisms, namely water uses Sensible Heat Storage, and the PCM Latent heat storage. The applied computational domain represents a single tube of a heat exchanger (HE), and so it comprises of a copper tube with aluminium fins. The geometric characteristics of the domain are taken in accordance with commercially used HE’s for HTES applications [1]. The characteristics studied are the stored energy of the system, the temperature of the heat transfer fluid (HTF) in the outlet and the temperature of the storage medium. The results of the simulations showed that for the same mass of storage mediums, the PCM can store more energy than water, for the same temperature of the HTF, as expected. Also, the temperature of the medium for the sensible heat storage rises linearly with the energy stored inside it, while in the latent heat storage mechanism, the temperature of the medium rises linearly till the melting (or solidification) of it, then stays almost steady until the melting of the whole volume and then rises again until it reaches the temperature of the HTF.

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Sunden, Bengt Ake, Zan Wu, and Dan Huang. "Comparison of heat transfer characteristics of aviation kerosene flowing in smooth and enhanced mini tubes at supercritical pressures." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 3/4 (May 3, 2016): 1289–308. http://dx.doi.org/10.1108/hff-12-2015-0538.

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Анотація:

Purpose – The purpose of this paper is to numerically investigate the heat transfer performance of aviation kerosene flowing in smooth and enhanced tubes with asymmetric fins at supercritical pressures and to reveal the effects of several key parameters, such as mass flow rate, heat flux, pressure and inlet temperature on the heat transfer. Design/methodology/approach – A CFD approach is taken and the strong variations of the thermo-physical properties as the critical point is passed are taken into account. The RNG k-ε model is applied for simulating turbulent flow conditions. Findings – The numerical results reveal that the heat transfer coefficient increases with increasing mass flow rate and inlet temperature. The effect of heat flux on heat transfer is more complicated, while the effect of pressure on heat transfer is insignificant. The considered asymmetric fins have a small effect on the fluid temperature, but the wall temperature is reduced significantly by the asymmetric fins compared to that of the corresponding smooth tube. As a result, the asymmetric finned tube leads to a significant heat transfer enhancement (an increase in the heat transfer coefficient about 23-41 percent). The enhancement might be caused by the re-development of velocity and temperature boundary layers in the enhanced tubes. With the asymmetric fins, the pressure loss in the enhanced tubes is slightly larger than that in the smooth tube. A thermal performance factor is applied for combined evaluation of heat transfer enhancement and pressure loss. Research limitations/implications – The asymmetric fins also caused an increased pressure loss. A thermal performance factor ? was used for combined evaluation of heat transfer enhancement and pressure loss. Results show that the two enhanced tubes perform better than the smooth tube. The enhanced tube 2 gave better overall heat transfer performance than the enhanced tube 1. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated. Practical implications – The asymmetric fins increased the pressure loss. The evaluation of heat transfer enhancement and pressure loss Results showed that the two enhanced tubes perform better than the smooth tube. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated to make the results more engineering useful. Originality/value – The paper presents unique solutions for thermal performance of a fluid at near critical state in smooth and enhanced tubes. The findings are of relevance for design and thermal optimization particularly in aerospace applications.

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Dhaou, Mohamed Houcine, Sofiene Mellouli, Faisal Alresheedi, and Yassine El-Ghoul. "Numerical Assessment of an Innovative Design of an Evacuated Tube Solar Collector Incorporated with PCM Embedded Metal Foam/Plate Fins." Sustainability 13, no. 19 (September 24, 2021): 10632. http://dx.doi.org/10.3390/su131910632.

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The objective of this manuscript is to study the possibility of improving the thermal performance of an Evacuated Tube Solar Collector (ETSC) with the integration of a Phase Change Material (PCM) incorporated into metallic foam and fitted with plate fins. A 2D mathematical model has been proposed. Two types of metal foams (copper and nickel) were inserted. In addition, the effect of metal foam pore size of on heat transfer was studied. The results were acquired through numerical simulations of four different cases; namely, Case 1: pure PCM, Case 2: with metal foam, Case 3: with fins and Case 4: with metal foam and fins. The evaluation procedure involved observing the total change in Heat Transfer Fluid (HTF) temperature and melted PCM fraction during a single day. The results proved that the thermal performance of ETSC is improved considerably by inserting metal foam and fins simultaneously. The time required for the whole process is improved by almost 9% compared to the case of pure PCM, and 2% compared to the case of inserting only plate fins. Results revealed that the pore size of the metal foams slightly affects the dynamic process of heat storage/release in the ETSC/PCM system.

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Більше джерел

Дисертації з теми "HTF TUBE WITH FINS"

Ebeling, Christopher P. "Measurements and Predictions of the Heat Transfer at the Tube-Fin Junction for Louvered Fin Heat Exchangers." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/10140.

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Анотація:

Compact heat exchangers are usually characterized by a large heat transfer surface per unit of volume. These characteristics are useful when thermal energy between two or more fluids must be exchanged without mixing. Most compact heat exchangers are liquid-to-air heat exchangers, with approximately 85% of the total thermal resistance occurring on the air side of the heat exchanger. To reduce the space and weight of a compact heat exchanger, augmentation strategies must be proposed to reduce the air side resistance. However, before any strategies to augment the air side heat transfer can be proposed, a thorough insight of the current mechanisms that govern air side heat transfer is required. The tube wall heat transfer results presented in this paper were obtained both experimentally and computationally for a typical compact heat exchanger design. Both isothermal and constant heat flux tube walls were studied. For the experimental investigation, a scaled-up model of the louvered fin-tube wall was tested in a flow facility. Although computational results for the isothermal tube wall are shown, control of the experimental isothermal tube wall proved to be unrealistic and only heat transfer measurements along the constant heat flux tube wall were made. For the constant heat flux tube wall, reasonable agreement has been achieved between the measurements and the steady, three-dimensional computational predictions. The results of the study showed that high heat transfer coefficients existed at the entrance to the louver array as well as in the louver reversal region. Vortices created at the leading edge of the louvers augmented heat transfer by thinning the tube wall boundary layer. Results indicate that an augmentation ratio of up to 3 times can occur for a tube wall of a louvered fin compact heat exchanger as compared to a flat plate.
Master of Science

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Lawson, Michael James. "Practical Applications of Delta Winglets in Compact Heat Exchangers with Louvered Fins." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34141.

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Анотація:

Compact heat exchangers are widely used by the automotive industry in systems that cool engine components. Louvered fin heat exchangers are used over their continuous fin counterparts because of the significant advantages they provide in heat transfer efficiency, while only causing small increases in overall pressure losses. With the recent emphasis that has been placed on reducing fuel consumption, decreasing the size of the compact heat exchanger has become an important concern. With reduction in size comes not only weight savings, but also a decrease in frontal area in a vehicle that must be dedicated to the heat exchanger, allowing for more aerodynamic vehicle designs.

Air-side resistance on the tube wall and louvered fin surfaces comprises over 85% of total resistance to heat transfer in louvered fin heat exchangers. The tube wall surface is considered the primary surface for heat transfer, where the temperature between the working fluid and convecting air is at a maximum. Recent studies have shown that implementing delta winglets on louvered fins along the tube wall is an effective method of augmenting tube wall heat transfer. In this thesis, the effect of delta winglets is investigated in both two- and three-dimensional louvered fin arrays. For both geometries, winglets are simulated in a manufacturable configuration, where piercings in the louvered fins that would result from the winglet manufacturing process are modeled.

Using the two-dimensional geometry to model tube wall heat transfer was shown not to accurately predict heat transfer coefficients. In a two-dimensional geometry, winglets were found not to be an effective means for augmenting tube wall heat transfer and caused only 8% augmentation. Using the three-dimensional geometry, winglets with simulated piercings were observed to cause up to 24% tube wall heat transfer augmentation, with a corresponding increase in pressure losses of only 10%.

Master of Science

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Silva, Bruno José Gonçalves da. "Avaliação técnica SPME/LC na análise de antidepressivos em amostra de plasma para fins de monitorização terapêutica." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-17082007-114009/.

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Анотація:

As recentes técnicas miniaturizadas de preparo de amostra, microextração em fase sólida (SPME) e in tube SPME, apresentam uma série de vantagens em relação aos métodos clássicos de extração (extração líquido-líquido e extração em fase sólida), tais como: não requer instrumentação analítica sofisticada, utilização de pequenas quantidades de solventes orgânicos, rápido processo operacional, permite automação das análises, a reutilização das fases extratoras, e integra em um único sistema a extração, concentração e introdução da amostra no cromatográfico. Esta dissertação tem como objetivo a padronização, validação e comparação dos métodos SPME/LC-UV com dessorção off line e in tube SPME/LC-UV, para a análise dos antidepressivos da nova geração (mirtazapina, citalopram, paroxetina, duloxetina, fluoxetina e sertralina) em amostras de plasma para fins de monitorização terapêutica. As variáveis: fase extratora, pH da matriz, tempo e temperatura de extração e de dessorção e força iônica apresentaram grande influência na eficiência do processo SPME. O método SPME/LC-UV padronizado, apresentou limite de quantificação (LQ) de 25 a 50 ng mL-1, ampla faixa de linearidade (LQ ? 500 ng mL-1, r2 > 0,9970) e precisão inter ensaios com coeficientes de variação menor que 15% para todos os analitos. Apesar das baixas taxas de recuperação obtidas, de 8,1% (citalopram) a 17,1% (mirtazapina), o método SPME/LC-UV apresentou seletividade e sensibilidade analítica adequada. As variáveis: pH da matriz, fluxo e número de ciclos aspirar/dispensar e volume de amostra apresentaram grande influência na eficiência do processo in tube SPME. A etapa de precipitação de proteínas do plasma, anterior ao processo de extração, foi necessária para a eliminação dos compostos endógenos. O método in tube SPME/LC-UV padronizado apresentou seletividade adequada, precisão inter ensaios com coeficiente de variação menor que 10%, LQ de 20 a 50 ng mL-1, linearidade na faixa de concentração do LQ a 500 ng mL-1, com r2 > 0,9983 para todos os analitos e recuperação absoluta de 5,32% (mirtazapina) a 43,5% (sertralina). A técnica in tube SPME, quando comparada à SPME, permitiu a automação das análises, menor exposição do analista às amostras biológicas e solventes orgânicos, menor tempo de análise e menor volume de amostra de plasma. A eficácia dos métodos, SPME/LC-UV e in tube SPME/LC-UV, foi comprovada através das análises de amostras de plasma de pacientes em terapia com os antidepressivos, para fins de monitorização terapêutica.
The recent miniaturized sample techniques preparation, solid phase microextraction (SPME) and in tube SPME, present several advantages when compared with classic extraction methods (liquid-liquid extraction and solid phase extraction), such as: it does not require sophisticated analytical instrumentation, use small organic solvent amounts, fast operational process, automation of the analyses, reuse extraction phases, and incorporates, into a single procedure, sample extraction, concentration and sample introduction. The aim of this work is development, validation and comparison of methods SPME/LC-UV with off line desorption and in tube SPME/LC-UV, for analyses of antidepressants of the new generation (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine and sertraline) in plasma samples for therapeutic drug monitoring. Variables: extraction phase, matrix pH, time and temperature of extraction and desorption and ionic strength showed great influence in SPME process efficiency. The method SPME/LC-UV presented limit of quantification (LOQ) variety from 25 to 50 ng mL-1, wide range the of linearity (LOQ 500 ng mL-1, r2 > 0.9970) and interassays precision with coefficient of variation lower than 15% for all analytes. Although the low recovery, from 8.1% (citalopram) to 17.1% (mirtazapine), the method SPME/LC-UV presented adequate selectivity and analytical sensitivity. Variables: matrix pH, flow and number of aspirate/dispense cycles and sample volume showed great influence in the in tube SPME process efficiency. The protein precipitation of the plasma steps, previous to the extraction process, was necessary for the endogenous compounds elimination. The method in tube SPME/LC showed adequate selectivity, interassays precision with coefficient of variation lower than 10%, LOQ variety from 20 to 50 ng mL-1, linearity in range concentration from LOQ to 500 ng mL-1, with r2 > 0.9983 for all analytes and recovery from 5.32% (mirtazapine) to 43.5% (sertraline). The technique in tube SPME, compared with the SPME, permitted the automation of the analyses, minor exposition of the analyst to the biological samples and organic solvent, shorter analyses time and minor plasma sample volume. The effectiveness methods, SPME/LC-UV and in tube SPME/LC-UV, was proven through the analyses of plasma samples of patients in therapy with antidepressants, for therapeutic drug monitoring.

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Mahdi, Jasim M. "ENHANCEMENT OF PHASE CHANGE MATERIAL (PCM) THERMAL ENERGY STORAGE IN TRIPLEX-TUBE SYSTEMS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1533.

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Анотація:

The major challenge associated with renewable-energy systems especially solar, is the supply intermittency. One effective solution is to incorporate thermal energy storage components utilizing phase change materials (PCMs). These materials have the potential to store large amounts of energy in relatively small volumes and within nearly an isothermal storage process. The primary drawback of today’s PCMs is that their low thermal conductivity values critically limit their energy storage applications. Also, this grossly reduces the melting/ solidification rates, thus making the system response time to be too long. So, the application of heat transfer enhancement is very important. To improve the PCM storage performance, an efficient performing containment vessel (triplex-tube) along with applications of various heat transfer enhancement techniques was investigated. The techniques were; (i) dispersion of solid nanoparticles, (ii) incorporation of metal foam with nanoparticle dispersion, and (iii) insertion of longitudinal fins with nanoparticle dispersion. Validated simulation models were developed to examine the effects of implementing these techniques on the PCM phase-change rate during the energy storage and recovery modes. The results are presented with detailed model description, analysis, and conclusions. Results show that the use of nanoparticles with metal foam or fins is more efficient than using nanoparticles alone within the same volume usage. Also, employing metal foam or fins alone results in much better improvement for the same system volume.

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KUMAR, NITIN. "PERFORMANCE ANALYSIS OF LATENT HEAT THERMAL ENERGY STORAGE SYSTEM USING FINS." Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19964.

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Анотація:

The Purpose of the current work is to examine the performance of a PCM i.e. phase change material within a Trapezoidal shape unit to store heat energy. The Numerical simulation is done using ANSYS 22 software to simulate and analyze the results, focusing on temperature and time contours throughout melting part and solidification part of PCM. Storage unit features a square shape tube in which fins are attached to the tube to study the HTR. One main challenge encountered in PCM melting is the collection of solid material at the lowermost in a process of charging and LF rests at the uppermost during the process of discharging. The numerical simulation explains the temperature distribution across various ranges during the melting and solidification phases. The system's effectiveness and performance are enhanced by using this setup. The simulation's results show that throughout the melting process, the liquid percentage rapidly grows, reaching 78% during the first 250 minutes. This is because heat is transferred through convection and conduction. However, after then, heat is transferred primarily through conduction, which results in a decline in the rate of liquid fraction and a total melting time of 2390 minutes for the PCM. In a similar manner, following the first 250 minutes of discharge, the solid percentage increases more slowly, solidifying to about 34%. However, it takes 1660 minutes for the PCM to fully solidify. The study's finding show that using a trapezoidal form geometry and including fins may enhance the melting and solidification part for a TESs.

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Che, Lin Chin, and 林志澤. "Heat Transfer of Reciprocating Curved Tube Fitted With Longitudinal Fins." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/59490803320664879363.

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碩士
國立高雄海洋科技大學
輪機工程研究所
94
This experimental study examines the heat transfer of the reciprocating curved tube fitted with longitudinal fins with the attempts to evaluate the heat transfer augmentation generated by the longitudinal fins and to develop the heat transfer correlation for the design of piston cooling system. The circumferential heat transfer distributions along five cross-sections of the curved fin-tube were measured. Heat transfer tests were performed with five reciprocating frequencies of 0, 0.83, 1.25, 1.67 and 2 Hz for each tested Reynolds number of 5000, 10000, 15000, 20000, 24000. The selected heat-transfer results in this thesis illustrated the heat transfer physics inside the reciprocating curved tube fitted with longitudinal fins. The Nusselt numbers obtained from the reciprocating and static test-conditions were compared to unravel the influences of reciprocation on heat transfer. Within the parametric range studied, the ratios of Nusselt number between the reciprocating and static tubes were in the range of 0.67~1.12. A set of heat transfer correlations was derived to permit the evaluation of individual and interactive impacts of centrifugal force, inertial force, reciprocating force and reciprocating buoyancy on heat transfer, which provided the design reference for piston cooling system.

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Deorah, Shashank. "CFD Analysis of a vertical tube having internal fins for the Natural Convection." Thesis, 2012. http://ethesis.nitrkl.ac.in/3330/1/Thesis.pdf.

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The heat transfer rate to a fluid flowing in pipe can be enhanced by the use of internal fins. This thesis concerned with computer simulation study of vertical tube with helical fins used to enhance their heat transfer performance subjected to natural convection heat transfer. All the main parameters which can significantly influence the heat transfer performance of finned tube has been analyzed. Natural convection in a vertical tube without fins was taken as the reference tube and different fin patterns such as a single fin with large no. of turns like coiled shape and large no. of fins with single turn is compared with reference tube on the basis of different parameters such as heat transfer rate, surface nusselt number, heat transfer coefficient, fin effectiveness etc. There are some dimensionless numbers which affect the natural convection such as nusselt number which is the function of Reynolds number, grashof number and prandlt number, Rayleigh number which is the product of grashoff and prandtl number. After getting best fin configuration compared it with different fin profile such as rectangular cross section,tapered fin with trapezoidal cross section and hyperbolic cross section. All the computer simulation has been done on the ANSYS 13.0 . The Navier-stokes equations were used to solve for the fluid flow inside the tube and the Boussinesq approximation was used to get the buoyancy effect. Aluminium is used for the fin material and air is taken as the fluid flowing inside the tube and the flow is taken as laminar. It was found that the large number of fins with single turn is more efficient then other fin patterns, as there is less flow resistance, high heat transfer rate.

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Nangia, Aniket. "CFD analysis of a vertical tube with external helical fins in natural convection." Thesis, 2012. http://ethesis.nitrkl.ac.in/3244/1/108ME060_ANIKET_NANGIA_THESIS.pdf.

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Convective heat transfer between a surface and the surrounding fluid in a heat exchanger has been a major issue and a topic of study for a long time. In this study, an attempt has been made to study the effect of various fin configurations on the total heat transfer from a vertical tube. The temperature contours, velocity vectors, surface nusselt number, total heat transfer rate from the fins as well as wall of the tube were calculated and plotted using ANSYS 13.0. The Navier-stokes equations were used to solve for the fluid flow inside the tube and the Boussinesq approximation was used to model the buoyancy effect. Aluminum was used as the base metal for the pipe as well as the fin material. The fluid surrounding the tube was air. Three different configurations have been used in this analysis. The three configurations were compared on the basis of total heat transfer. It was found that the fin configuration with trapezoidal fins had the most heat transfer rate.

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Yun-LungChung and 鍾昀龍. "An Inverse Design Problem in Estimating the Optimal Shape of the Annular Fins Adhered to a Bare Tube of an Evaporator." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/283296.

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博士
國立成功大學
系統及船舶機電工程學系
104
This dissertation is intended to find an optimum shape and fin efficiency of annular fin adhere to the bare tube of evaporator for the air conditioner when considering the thermal properties of fin are either constant or temperature-dependent. It uses the conjugate gradient method (CGM) of inverse heat conduction problem to design an optimum annular fin based on the desired fin efficiency and fin volume. The amount of vapor in the ambient air influences fin shape a lot, as a result, it needs to consider the specific humidity when the optimum annular fin shape is designed. There are three types of annular fin surfaces including dry, fully wet and partially wet, respectively. In order to find the temperature distribution on bare tube and the fin, the finite difference method is utilized. Based on the temperature difference between the fin and the surrounding air, the heat flux and the efficiency of annular fin can be calculated in the dry, fully wet and partially wet conditions. This dissertation consists six chapters. Chapter 1 is the preface as stated above. Chapter 2 shows the computational procedure of the inverse problem in determining the linear optimal annular fin shapes by using the conjugate gradient method under dry, fully wet and partially wet conditions. It clearly illustrates the direct problem, sensitivity problem, adjoint problem and gradient equation and leads to an objection function and fin efficiency equation. On the above process of numerical computation, the thermal conductivities kf and kw and Biot numbers Bii, Bio and Bia are considered constants. Chapter 3 introduces the computation procedure to estimate nonlinear dry, fully wet and partially wet optimum annular fin shapes by assuming the thermal conductivities kf and kw, Biot numbers Bii and Bia are temperature-dependent. The CGM is utilized to solve the present nonlinear inverse design problem. Chapter 4 illustrates the numerical results for the optimal shapes and fin efficiency for linear annular fin under the dry, fully wet and partially wet conditions based on the desired fin volume and fin efficiency by using different Biot numbers Bii and Bia, fin volume V, conductivity ratio G and relative humidity. The technique of optimal fin design problem can indeed obtain the maximum fin efficiency when compared with five common annular fins. Annular finned-tube heat exchangers are widely used in applications of air-conditioning and refrigeration systems. Besides, the thermal parameters of the fin are also function of temperatures in many practical engineering applications. Based on the above stated two conditions a nonlinear optimum annular fin design problem is considered in Chapter 5. The conjugate gradient method (CGM) is utilized as the optimization algorithm based on the desired fin efficiency and fin volume. The numerical experiments show that the optimum annular fin has the highest fin efficiency among six annular fins with the same operating fin conditions. When the Biot numbers for ambient air (Bia) varied, the optimum fin efficiency and optimum fin shape of the nonlinear annular fin also changed. However, when the Biot numbers for the inner tube (Bii), the thermal conductivities of the bare tube (kw) and the annular fin (kf) varied, the optimum fin shape remained almost the same. This implies that Bii, kw and kf have a limited influence on the optimum annular fin shape. Based on the above studies it can be concluded that the conjugate gradient method (CGM) with iterative regularization process is applied successfully to the fin design problem to estimate the optimum shape of annular fins with constant and temperature-dependent thermal parameters.

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Ravi, Gurunarayana. "Study of Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid." 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2008-12-231.

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The heat transfer behavior of phase change material fluid under laminar flow conditions in circular tubes and internally longitudinal finned tubes are presented in this study. Two types of boundary conditions, including uniform axial heat flux with constant peripheral temperature and uniform axial and peripheral temperature, were considered in the case of circular tubes. An effective specific heat technique was used to model the phase change process assuming a hydrodynamically fully-developed flow at the entrance of the tube. Results were also obtained for the phase change process under hydro dynamically and thermally fully developed conditions. In case of a smooth circular tube with phase change material (PCM) fluid, results of Nusselt number were obtained by varying the bulk Stefan number. The Nusselt number results were found to be strongly dependent on the Stefan number. In the case of a finned tube two types of boundary conditions were studied. The first boundary condition had a uniform axial heat flux along the axis of the tube with a variable temperature on the peripheral surface of the tube. The second boundary condition had a constant temperature on the outer surface of the tube. The effective specific heat technique was again implemented to analyze the phase change process under both the boundary conditions. The Nusselt number was determined for a tube with two fins with different fin height ratios and fin thermal conductivity values. It was determined that the Nusselt number was strongly dependent on the Stefan number, fin thermal conductivity value, and height of the fins. It was also observed that for a constant heat axial flux boundary condition with peripherally varying temperature, the phase change slurry with the internally finned tube performed better than the one without fins. A similar trend was observed during the phase change process with internal fins under the constant wall temperature boundary condition.

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Книги з теми "HTF TUBE WITH FINS"

Heat transfer and pressure drop performance of a finned-tube heat exchanger proposed for use in the NASA Lewis altitude wind tunnel. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1985.

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Частини книг з теми "HTF TUBE WITH FINS"

Nishi, M., X. M. Wang, K. Yoshida, T. Takahashi, and T. Tsukamoto. "An Experimental Study on Fins, Their Role in Control of the Draft Tube Surging." In Hydraulic Machinery and Cavitation, 905–14. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-010-9385-9_92.

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Luo, Jiaen, Zhaosong Fang, Lan Tang, and Zhimin Zheng. "Numerical Simulation of Heat Transfer and Pressure Drop Characteristics of Elliptical Tube Perforated Fins Heat Exchanger." In Environmental Science and Engineering, 329–38. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-13-9524-6_35.

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Saha, Sujoy Kumar, Hrishiraj Ranjan, Madhu Sruthi Emani, and Anand Kumar Bharti. "Oval and Flat Tube Geometries, Row Effects in Tube Banks, Local Heat Transfer Coefficient on Plain Fins, Performance Comparison, Numerical Simulation and Patents, Coatings." In Heat Transfer Enhancement in Externally Finned Tubes and Internally Finned Tubes and Annuli, 69–84. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20748-9_5.

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Beura, S., R. Ray, U. K. Mohanty, and Dhirendra Nath Thatoi. "Heat Transfer in the Annular Region of a Double Tube Heat Exchanger with Continuous Longitudinal Rectangular Fins Under Turbulent Flow Condition." In Lecture Notes in Mechanical Engineering, 469–79. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4795-3_43.

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Chedid, Teddy, Erwin Franquet, Jérôme Pouvreau, Pierre Garcia, and Jean-Pierre Bédécarrats. "Numerical Study of the Influence of Fins’ Geometry on the Thermal Performances of a Vertical Shell and Tube Latent Heat Thermal Energy Storage." In Atlantis Highlights in Engineering, 93–110. Dordrecht: Atlantis Press International BV, 2023. http://dx.doi.org/10.2991/978-94-6463-156-2_8.

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Taler, Dawid, Jan Taler, and Marcin Trojan. "The CFD Based Method for Determining Heat Transfer Correlations on Individual Rows of Plate-Fin and Tube Heat Exchangers." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97402.

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The chapter provides an analytical mathematical model of a car radiator, which includes different heat transfer coefficients (HTCs) on the first and second row of pipes. The air-side HTCs in the first and second row of pipes in the first and second pass were calculated using the correlations for the Nusselt number, which were determined by CFD simulation using the ANSYS software. Mathematical models of two radiators were built, one of which was manufactured of round tubes and the other of oval tubes. The model permits the determination of thermal output of the first and second row of tubes in the first and second pass. The small relative differences between the thermal capacities of the heat exchanger occur for different and uniform HTCs. However, the heat flow rate in the first row is much greater than the heat flow in the second row if the air-side HTCs are different on the first and second tube row compared to a case where the HTC is uniform in the whole heat exchanger. The heat transfer rates in both radiators calculated using the developed mathematical model were compared with those determined experimentally. The method for modeling of plate-fin and tube heat exchanger (PFTHE) proposed in the paper does not require empirical correlations to calculate HTCs both on the air side and on the inner surfaces of pipes. The presented method of calculating PFTHEs, considering different air-side HTCs evaluated using CFD modeling, may considerably reduce the cost of experimental research concerning new design heat exchangers implemented in manufacturing.

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"41 Economizer tube solid or serrated fins." In Industrial Water Tube Boiler Design, 130–32. De Gruyter, 2021. http://dx.doi.org/10.1515/9783110757088-041.

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"Robert D. Reed Low Fins in Shell-and-Tube Exchangers." In Heat Transfer Design Methods, 155–80. CRC Press, 1991. http://dx.doi.org/10.1201/9781482277050-8.

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Nhan Phan, Thanh. "A Review on Condensation Process of Refrigerants in Horizontal Microfin Tubes: A Typical Example." In Heat Transfer [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105875.

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Heat transfer performance of refrigerant on the condensation process is very important in the designing of condensation equipment, especially in air conditioning and refrigeration systems. The outstanding advantages of microfin tubes are reducing the weight and size of condensers and also reducing the amount of refrigerant on the system. Reviewing the general concept of condensation and detailing the formation of flow pattern map that is also the procedure to determine heat transfer coefficient and pressure drop during condensation process of refrigerant inside the horizontal microfin tubes would be considered. Also, a typical example will be presented to illustrate a detailed procedure to calculate the value of heat transfer coefficient and pressure drop during the condensation process in horizontal microfin tubes. The data results show that microfin tube J60 with 60 number of fins inside 8.96 mm inner diameter, 0.2 mm height of fin, 40o of apex angle and 18o of helix angle, the condensation procedure of R1234ze at 35°C, heat flux of 8.62 kW/m2, and mass flux of 222 kg/m2s that could be estimated with heat transfer coefficient would be reduced from 8160.4 [W/m2 K] to 1413.8 [W/m2 K] follow with quality x changes from 0.99 to 0.01, and the maximum pressure drop of this process is 3173.8 [Pa/m].

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Тези доповідей конференцій з теми "HTF TUBE WITH FINS"

Kozak, Y., T. Rozenfeld, and G. Ziskind. "Analysis of a Latent Heat Storage Device With Radial Fins." In ASME 2013 7th International Conference on Energy Sustainability collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/es2013-18103.

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Phase-change materials (PCMs) can store large amounts of heat without significant change of their temperature during the phase-change process. This effect may be utilized in thermal energy storage, especially for solar-thermal power plants. In order to enhance the rate of heat transfer into PCMs, one of the most common methods is the use of fins which increase the heat transfer area that is in contact with the PCM. The present work deals with a latent heat thermal storage device that uses a finned tube with an array of radial fins. A heat transfer fluid (HTF) flows through the tube and heat is conducted from the tube to the radial fins that are in contact with the bulk of the PCM inside a cylindrical shell. The thermal storage charging/discharging process is driven by a hot/cold HTF inside the tube that causes the PCM to melt/solidify. The main objective of the present work is to demonstrate that close-contact melting (CCM) can affect the storage unit performance. Accordingly, two different types of experiments are conducted: with the shell exposed to ambient air and with the shell submerged into a heated water bath. The latter is done to separate the PCM from the shell by a thin molten layer, thus enabling the solid bulk to sink. The effect of the solid sinking and close-contact melting on the fins is explored. It is found that close-contact melting shortens the melting time drastically. Accordingly, two types of models are used to predict the melting rate: numerical CFD model and analytical/numerical close-contact melting model. The CFD model takes into account convection in the melt and the PCM property dependence on temperature and phase. The analytical/numerical CCM model is developed under several simplifying assumptions. Good agreement is found between the predictions and corresponding experimental results.

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Lim, Celine S. L., Vivek R. Pawar, and Sarvenaz Sobhansarbandi. "Thermal Performance Analysis of a Novel U-Tube Evacuated Tube Solar Collector." In ASME 2020 14th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/es2020-1674.

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Abstract Solar water heating (SWH) systems are the most common application of renewable energy technology that converts solar radiation into useful energy for domestic/industrial activities. The novelty of this study is the design of a new SWH that combines the heat transfer and storage both in a single unit. The selected type of collector for this purpose is an evacuated tube solar collector (ETC). The new design of the ETC has been developed by applying a U-tube inside the collector which contains the heat transfer fluid (HTF). The HTF flows into an external heat exchanger that transfers heat to the water. The implementation of sugar alcohol namely Erythritol (C4H10O4) as the HTF for moderate operating temperature applications was investigated. Moreover, the utilization of solid-liquid phase change material, Tritriacontane paraffin (C33H68), inside the ETC, allows direct heat storage on the system and delayed release of heat. A computational fluid dynamics (CFD) modeling of a single U-tube ETC is performed using ANSYS Fluent in stagnation (on-demand) operation. A 3D model of the ETC is developed and the appropriate boundary conditions are applied. Moreover, the thermal performance comparison of U-tube vs heat pipe ETC has been done. The results from this study shows the maximum fin temperature difference of 46°C of U-tube ETC compared with heat pipe ETC.

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Alnaimat, Fadi, Bobby Mathew, Abdel-Hamid I. Mourad, and S. A. B. Al Omari. "Modeling and Simulation of Thermal Energy Storage for Solar Energy Utilization." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10326.

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Abstract A significant research has been done on the enhancement of thermal energy storage systems. This article details the numerical study conducted to understand the heat transfer and fluid flow characteristics of a concentric thermal energy storage subjected to different heat transfer fluid (HTF) velocities. Water is used as the working heat transfer fluid. The influence of flow parameter primarily the HTF velocity is studied in this article. Studies are conducted for concentric thermal energy storage diameter of 25 mm, and 10 mm inner diameter of concentric pipe, 200 mm length, and HTF velocity of 0.02, 0.1, 0.3, 0.5 m/s. It is found that the utilization of fins improves the heat transfer in tube in tank thermal storage system. Computational fluid dynamics (CFD) enables a more detailed study of the phase change thermal characteristics.

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Romero-Méndez, Ricardo, Rafael Adame, and Mihir Sen. "Parametric Study of Conjugate Heat Transfer in a Plate-Fin and Tube Heat Exchanger." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24113.

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Abstract A finite element code is used to analyze the conjugate heat transfer over the external side of a single-row plate-fin and tube heat exchanger. The conditions for which the simulations are conducted are similar to those of real plate-fin and tube heat exchangers where both conduction through the fins and convection over them are present. The influence of several parameters on the temperature distribution and local heat transfer is analyzed. From the simulations it is seen that the region of high heat transfer that appears in the leading edge of the fins is the most affected by the finite conductivity of the fin material. There is a decrease of the local heat transfer there when either the fin conductivity or the fin thickness is decreased. This is due to the decrease of the temperature gradient between the fin leading edge and the entering fluid. The effect of increasing the Reynolds number is to reduce the efficiency of the fins. This causes the local Nusselt number not to grow as fast as it would have grown if the fins had infinitely large conductivity. Finally, the effect of the eccentricity of the tube with respect to the fin length is studied. The results illustrate that by moving the tube nearer to the trailing edge of the fin, the area of low heat transfer behind the tube is reduced in size and, at the same time, the temperature gradient between the fin leading edge and the fluid above is reduced causing a reduction of the heat transfer ahead of the tube. This suggests that there is an optimum position of the tube with respect to the fin length.

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Khan, Zakir, and Zulfiqar Ahmad Khan. "Development in Paraffin Based Thermal Storage System Through Shell and Tubes Heat Exchanger With Vertical Fins." In ASME 2017 11th International Conference on Energy Sustainability collocated with the ASME 2017 Power Conference Joint With ICOPE-17, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/es2017-3276.

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Researchers are committed to develop robust and responsive technologies for renewable energy sources to avert from reliance on fossil fuels, which is the main cause of global warming and climate change. Solar energy based renewable energy technologies are valued as an important substitute to bridge gap between energy demand and generation. However, due to varying and inconsistent nature of solar energy during weather fluctuations, seasonal conditions and night times, the complete utilisation of technology is not guaranteed. Therefore, thermal energy storage (TES) system is considered as an imperative technology to be deployed within solar energy systems or heat recovery systems to maximise systems efficiency and to compensate for varying thermal irradiance. TES system can capture and store the excess amount of thermal energy during solar peak hours or recover from systems that would otherwise discard this excess amount of thermal energy. This stored energy is then made available to be utilised during solar off peak hours or night times. Phase change material (PCM) based TES system is appraised as a viable option due to its excellent adoption to solar and heat recovery systems, higher thermal storage density and wide range of materials availability. However, due to its low thermal conductivity (≅ 0.2 W/mK), the rapid charging and discharging of TES system is a challenge. Therefore, there is a need for efficient and responsive heat exchange mechanism to boost the heat transfer within PCM. In this study, transient analysis of two-dimensional computational model of vertical shell and tube based TES system is conducted. Commercial grade paraffin (RT44HC) is employed in shell as thermal storage material due to its higher thermal storage density, thermo-physical stability and compatibility with container material. Water is made to flow in tubes as heat transfer fluid. In this numerical study, the parametric investigations are performed to determine the enhancement in charging rate, discharging rate and thermal storage capacity of TES system. The parametric investigations involve geometrical orientations of tubes in shell with and without fins, inlet temperature and volume flow rate of HTF. It is evident from numerical results that due to increase in effective surface area for heat transfer by vertical fins, the charging and discharging rate of paraffin based TES system can be significantly increased. Due to inclusion of vertical fins, conduction heat transfer is dominant mode of heat transfer in both charging and discharging processes. Furthermore, vertical fins do not restrict natural convection or buoyancy driven flow as compared to horizontal fins. Similarly, the inlet temperature has a noticeable impact on both charging and discharging process. In melting process, the sensible enthalpy is boosted due to rise in inlet temperature and thus the whole system thermal storage capacity is enhanced. Likewise, the effect of volume flow rate of HTF on charging and discharging rate is moderate as compared to inlet temperature of HTF. The numerical results are validated by experimental results. To conclude, these findings present an understanding into how to increase charging and discharging rate of TES system so as to provide feasible design solutions for widespread domestic and commercial utilisation of TES technology.

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Koyama, Shigeru, Ken Kuwahara, and Koichi Nakashita. "Condensation of Refrigerant in a Multi-Port Channel." In ASME 2003 1st International Conference on Microchannels and Minichannels. ASMEDC, 2003. http://dx.doi.org/10.1115/icmm2003-1021.

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In the present paper, the local characteristics of pressure drop and heat transfer are investigated experimentally for the condensation of pure refrigerant R134a in four kinds of multi-port extruded aluminum tubes of about 1 mm in hydraulic diameter. Two tubes are composed of plane rectangular channels, while remaining two tubes are composed of rectangular channels with straight micro-fins. The experimental data of frictional pressure drop (FPD) and heat transfer coefficient (HTC) in plane tubes are compared with previous correlations, most of which are proposed for the condensation of pure refrigerant in a relatively large diameter tube. It is confirmed that parameters such as tube diameter, surface tension, free convection in FPD and HTC correlations should be taken into account more precisely. Considering the effects of surface tension and kinematic viscosity, new correlation of FPD is developed based on the Mishima-Hibiki correlation. New correlation of HTC is also developed modifying the effect of diameter in the correlation of Haraguchi et al. Both new correlations are compared with experimental data for tubes with micro-fins. Satisfactory agreement between experimental and predicted results is obtained. This means that the micro-fin effect is taken into account by using hydraulic diameter and the heat transfer enhancement effect of micro-fins is mainly due to the enlargement of heat transfer area.

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Christian, Joshua M., Jesus D. Ortega, and Clifford K. Ho. "Novel Tubular Receiver Panel Configurations for Increased Efficiency of High-Temperature Solar Receivers." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49431.

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Typical Concentrated Solar Power (CSP) central receiver power plants require the use of either an external or cavity receiver. Previous and current external receivers consist of a series of tubes connected to manifolds that form a cylindrical or rectangular shape such as in the cases of Solar One, Solar Two, and most recently the Ivanpah solar plant. These receivers operate at high surface temperatures (>600°C) at which point thermal re-radiation is significant. However, the geometric arrangement of these heat transfer tubes results in heat losses directly to the environment. This work focused on how to fundamentally reduce this heat loss through the manipulation of heat transfer tube configurations. Four receiver configurations are studied: flat receiver (base case study), a radial receiver with finned structures (fins arranged in a circular pattern on a cylinder), a louvered finned structure (horizontal and angled fins on a flat plate), and a vertical finned structure (fins oriented vertically along a flat plate). The thermal efficiency, convective heat loss patterns, and air flow around each receiver design is found using the computational fluid dynamics (CFD) code ANSYS FLUENT. Results presented in this paper show that alternative tubular configurations increase thermal efficiency by increasing the effective solar absorptance of these high-temperature receivers by increasing the light trapping effects of the receiver, reducing thermal emittance to the environment, and reducing the overall size of the receiver. Each receiver configuration has finned structures that take advantage of the directional dependence of the heliostat field resulting in a light trapping effect on the receiver. The finned configurations tend to lead to “hot” regions on the receiver, but the new configurations can take advantage of high local view factors (each surface can “see” another receiver surface) in these regions through the use of heat transfer fluid (HTF) flow patterns. The HTF reduces the temperatures in these regions increasing the efficiency of heat transfer to the fluid. Finally, the new receiver configurations have a lower overall optical intercept region resulting in a higher geometric concentration ratio for the receiver. Compared to the base case analysis (flat plate receiver), the novel tubular geometries results showed an increase in thermal efficiency.

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Sciacovelli, Adriano, Vittorio Verda, and Francesco Colella. "Numerical Investigation on the Thermal Performance Enhancement in a Latent Heat Thermal Storage Unit." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82720.

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The present paper describes the application of computational fluid-dynamics (CFD) for the analysis of the melting process in a single vertical shell-and-tube heat exchanger. The computations are based on a 2D axial-symmetric model that takes in account the phase change phenomenon by means of the enthalpy method. The numerical studies aimed at clarifying the importance of the different heat transfer mechanisms with a particular focus on natural convection demonstrating its fundamental importance on the phase change process by enhancing the heat transfer between HTF and solid PCM. the paper discusses the effect of two different common performance enhancement techniques: dispersion of high conductive nano-particles in the PCM and the introduction of radial fins. An extensive thermo-fluid dynamic study has been undertaken exploring the effect on the thermal performance enhancement of particle volume fraction and fins. The analysis shows that in comparison to the standard design, the performances of the LHTS unit in terms of charging time could be improved by up to 40 % for nano-particle enhancement. When fins are considered charging time can be reduced to one-third of its original value. Significant improvements are also achieved during the solidification process: discharge time is reduced of 33% with fins enhancement.

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Zhang, Y. H., J. Liu, Liang-Bi Wang, and Zhi-Min Lin. "THT FIN SIDE FLOW AND HEAT TRANSFER CHARACTERISTICS OF CIRCULAR TUBE BANK FIN HEAT EXCHANGER WITH THE TRANGULARWAVY FINS." In Second Thermal and Fluids Engineering Conference. Connecticut: Begellhouse, 2017. http://dx.doi.org/10.1615/tfec2017.hte.017645.

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Akarsh, A., and Sumer Dirbude. "Heat transfer enhancement in a PCM-based shell-and-tube-type thermal-energy storage device with nano-particle enhancement, addition of triangular annular fins, fin pitch, and HTF flow reversal." In Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India. Connecticut: Begellhouse, 2022. http://dx.doi.org/10.1615/ihmtc-2021.2030.

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