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Smith Eiamsa-ard - One of the best experts on this subject based on the ideXlab platform.
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Numerical Simulation and Optimization of Enhanced Heat Transfer in Helical Oval Tubes: Effect of Helical Oval Tube Modification, Pitch Ratio, and Depth Ratio
Heat Transfer Engineering, 2017Co-Authors: Pitak Promthaisong, Withada Jedsadaratanachai, Smith Eiamsa-ardAbstract:ABSTRACTFlow and heat transfer behaviors in the helical oval tube, alternate-twisted-direction helical oval tube and regularly-spaced helical oval tubes were numerically investigated. The helical oval tubes with eight oval tube depth Ratios (0.03, 0.04, 0.05, 0.06, 0.07, 0.10, 0.15 and 0.20) and nine oval tube Pitch Ratios (0.6, 0.8, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0) were examined in turbulent regime, Reynolds number ranged from 5000 – 20,000. The computational results showed that fully developed periodic flow and heat transfer in helical oval tubes commenced at around entrance length to characteristic diameter of 8–9. The decreasing depth Ratio and increasing Pitch Ratio helped to reduce the pressure loss of the tube heat exchanger. The maximum thermal performance of 1.30 was obtained by the use of the helical oval tube with depth Ratio of 0.05 and Pitch Ratio of 0.6 at the lowest Reynolds number of 5000. At similar conditions, typical helical oval tubes offered better heat transfer rate and thermal ...
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Heat transfer enhancement by helical screw tape coupled with rib turbulators
Journal of Mechanical Science and Technology, 2014Co-Authors: K. Nanan, Monsak Pimsarn, Chinaruk Thianpong, Smith Eiamsa-ardAbstract:The influence of helical screw tape coupled with rib turbulators (HST-R) on thermohydraulic characteristics in a circular tube has been experimentally investigated. The experiments were performed under constant heat flux condition for Reynolds number between 6,000 and 20,000. The rib-Pitch Ratio (p/D) was varied from 1.0 to 3.0 while rib-height Ratio (e/W) was varied from 0.5 to 1.5. The experimental results revealed that heat transfer and friction factor increase with increasing rib-height Ratio (e/W) and decreasing rib-Pitch Ratio (p/D). For the range examined, the HST-Rs with moderate rib-Pitch Ratio (p/D = 2) and the largest rib-height Ratio (e/W = 1.5) gave the maximum thermal performance factor while HST possessed thermal performance factor around average value of those of the tubes with HSTRs. The developed empirical correlations for Nusselt number, friction factor and thermal performance factor gave the predictions within ±4.4%, ±13% and ±4.2%, respectively as compared to the experimental data.
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Thermal performance evaluation of heat exchangers fitted with twisted-ring turbulators ☆
International Communications in Heat and Mass Transfer, 2012Co-Authors: Chinaruk Thianpong, K. Nanan, K. Yongsiri, Smith Eiamsa-ardAbstract:Abstract Heat transfer, friction factor and thermal performance characteristics in a tube equipped with twisted-rings (TRs) are experimentally investigated. The experiments were conducted using TRs with three different width Ratios (W/D = 0.05, 0.1 and 0.15) and three Pitch Ratios of (p/D = 1, 1.5 and 2) for Reynolds numbers ranging from 6000 to 20,000 using air as a test fluid. The typical circular rings (CRs) were also tested for an assessment. The experimental results reveal that most TRs yield lower Nusselt numbers and friction factor than CRs, except at the largest width Ratio (W/D = 0.15) and the smallest Pitch Ratio (p/D = 1.0). In addition, Nusselt number and friction factor increase as width Ratio increases and Pitch Ratio decreases. However, a maximum thermal performance factor is associated by TRs with the smallest width Ratio and Pitch Ratio. The empirical correlations of the heat transfer (Nu) and friction factor (f) are also included in this paper.
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Thermal Performance Assessment of Turbulent Tube Flow Through Wire Coil Turbulators
Heat Transfer Engineering, 2011Co-Authors: Smith Eiamsa-ard, Vichan Kongkaitpaiboon, Pongjet PromvongeAbstract:This paper presents characteristics of turbulent convective heat transfer in a tube fitted with wire coil turbulators. Two different wire coils are introduced: (1) with typical/uniform coil Pitch Ratio (CR) and (2) with periodically varying three-coil Pitch Ratio. Various uniform coil Pitch Ratios (CR = 4, 6, and 8) and two periodically varying coil Pitch Ratios, the D-coil (decreasing three-coil Pitch Ratio arrangement) and DI-coil (decreasing/increasing three-coil Pitch Ratio arrangement), are experimentally investigated in a uniform heat flux tube. The experiments are performed for turbulent flows with Reynolds numbers ranging between 4500 and 20,000. All of the experimental results are compared with those obtained from using the plain tube, while the thermal performance factor is evaluated under an equal pumping power constraint. The experimental results show that the use of the tube fitted with all wire coils leads to an advantage on the basis of heat transfer enhancement over the plain tube with no ...
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Influence of combined non-uniform wire coil and twisted tape inserts on thermal performance characteristics ☆
International Communications in Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsa-ard, P. Nivesrangsan, Suriya Chokphoemphun, Pongjet PromvongeAbstract:In this paper, heat transfer, friction factor and thermal performance behaviors in a tube equipped with the combined devices between the twisted tape (TT) and constant/periodically varying wire coil Pitch Ratio are experimentally investigated. The periodically varying three coil Pitch Ratios were arranged into two different forms: (1) D-coil (decreasing coil Pitch Ratio arrangement) and (2) DI-coil (decreasing/increasing coil Pitch Ratio arrangement) while the twisted tapes were prepared with two different twist Ratios. Each device alone is also tested and the results are subjected for comparison with those from the combined devices. The experiments were conducted in a turbulent flow regime with Reynolds numbers ranging from 4600 to 20,000 using air as the test fluid. Compared to each enhancement device, the heat transfer rate is further augmented by the compound devices. Over the range investigated, the highest thermal performance factor of around 1.25 is found by using DI-coil in common with the TT at lower Reynolds number. In addition, the empirical correlations of the heat transfer (Nu) and pressure drop (f) are also presented.
M Jafaryar - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of turbulent behavior of nanomaterial exergy loss and flow through a circular channel
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, Fatih Selimefendigil, M M Bhatti, Mehrdad Sheikholeslami, Houman BabazadehAbstract:To understand the impacts of adding twisted tape inside the tube with hybrid nanomaterial, the present paper has been examined with considering FVM. New testing fluid instead of water leads to lower exergy loss. Modeling outputs were carried out for different Pitch Ratio and Reynolds number. Decrement trend for secondary flow was reported when Pitch Ratio increases, and for this reason, convective flow reduces with rise of P which results in greater exergy drop. Turbulence intensity improves with augment of Re which provides stronger interaction of nanomaterial and tube wall. So, thinner boundary layer appears with rise of Re and exergy loss deteriorates.
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Simulation of thermal behavior of hybrid nanomaterial in a tube improved with turbulator
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, Elham Abohamzeh, Nguyen Dang Nam, Iskander TliliAbstract:Simulation of swirl flow intensification with the use of new device inside a pipe was performed in the current investigation. To improve the feature of testing fluid, hybrid nanopowders were dispersed. Outputs were exhibited in terms of contours. Tangential velocity of nanomaterial augments with the increase in Re, and stronger convective mode is obtained with the rise in Re. Thinner thermal boundary layer close to the wall is an output of reducing Pitch Ratio and leads to greater Nu. Augmenting contact surface area with a decline in Pitch Ratio leads to stronger secondary flow.
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Irreversibility of hybrid nanoparticles within a pipe fitted with turbulator
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, M Sheikholeslami, Houman BabazadehAbstract:In the current investigation, a novel shape of twisted tape was employed to improve the performance of nanomaterial. Hybrid nanoparticles were dispersed into water, and turbulent flow was considered. Not only the thermal behavior but also the irreversibility should be considered in the design of heat exchanger. Outputs based on FVM simulation are presented in the form of correlations and contours. Increment in efficiency is at a price of higher pressure loss. Pressure drop augments with a reduction in Pitch Ratio, and such behavior makes S _gen,f to augment due to thinner velocity boundary layer. Augmenting the Pitch Ratio causes temperature gradient to reduce; therefore, S _gen,th increases.
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Design of heat exchanger with combined turbulator
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Truong Khang Nguyen, M Jafaryar, Ahmad Shafee, Mohsen Sheikholeslami, Kotturu V.v. Chandra Mouli, Iskander TliliAbstract:In this article, influence of inserting new turbulator on resistance and heat transfer behaviors of a pipe has been analyzed. This kind of turbulator can be utilized for retrofit applications. Turbulent nanofluid flow is imposed. Homogenous approach for nanofluid and k–ɛ approach for turbulent modeling were involved. Contours are presented for different inlet velocity and Pitch Ratio. Results indicated that the lower the Pitch Ratio, the better is the temperature gradient. Nanofluid transfers more heat with decline of Pitch Ratio because of lower geneRation of longitudinal disturbance. As inlet velocity augments and Pitch Ratio decreases, nanofluid can scour the wall more easily and heat transfer rate is strengthened.
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nanofluid heat transfer augmentation and exergy loss inside a pipe equipped with innovative turbulators
International Journal of Heat and Mass Transfer, 2018Co-Authors: Mehrdad Sheikholeslami, M Jafaryar, Ahmad Shafee, Zhixiong Li, S. Saleem, Yu JiangAbstract:Abstract Exergy variations for forced convection of nanofluid through a pipe equipped with twisted tape turbulators have been simulated via Finite volume method. Roles of height Ratio, Pitch Ratio and Reynolds number on variation of nanofluid hydrothermal treatment, second law efficiency ( η II ) and exergy loss ( X d ) were presented. Suitable formulas for ( X d ) and ( η II ) are provided. Results reveal that exergy drop reduces with enhance of Reynolds number and height Ratio. Second law performance rises with augment of height Ratio while it reduces with augment of Pitch Ratio.
Mehdi Bahiraei - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of hydrothermal characteristics for flow within a circular tube equipped with twisted conical strip inserts under different alignments
Journal of the Taiwan Institute of Chemical Engineers, 2020Co-Authors: Mehdi Bahiraei, Khashayar GharagozlooAbstract:Abstract This study attempts to experimentally investigate the thermohydraulic characteristics inside a tube fitted with the staggered and non-staggered twisted conical strip inserts. The inserts are built via stereolithography 3D printer. The influences of geometrical attributes such as alignment type (i.e., staggered or non-staggered) and the Pitch Ratio as well as the Reynolds number (Re) on the Nusselt number (Nu) and friction factor (f) are examined. Because of flow mixing and vortex creation in the flow path, the tube fitted with the conical inserts has greater Nu and f in comparison with the smooth tube. The Nu and f have larger amounts in the tube having the non-staggered inserts in comparison with that with the staggered ones. With the Pitch Ratio elevation, the Nu and f diminish, while the elevation in the Re decreases the f and enhances the Nu. Thus, the highest Nusselt number and pressure drop belong to the non-staggered insert with Pitch Ratio of 2.5 and Reynolds number of 2250 with amounts of 15.15 and 795 Pa, respectively. The highest improvement of the Nusselt number in comparison with the plain tube occurs at Reynolds number of 350 for the non-staggered insert with Pitch Ratio of 2.5, which is recorded about 133.8%. Besides, the performance evaluation criterion (PEC) is higher than 1 at Re numbers of 820 and less than 820, which shows the proper merit of applying both the staggered and non-staggered inserts in this Re span. For small Re, the non-staggered inserts lead to larger PEC than the staggered ones, while an opposite outcome is observed for the high Reynolds numbers. The highest PEC is about 1.56, which belongs to the non-staggered alignment with Pitch Ratio of 5 and Reynolds number of 350.
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Experimental study on effect of employing twisted conical strip inserts on thermohydraulic performance considering geometrical parameters
International Journal of Thermal Sciences, 2020Co-Authors: Mehdi Bahiraei, Khashayar Gharagozloo, Hossein MoayediAbstract:Abstract In this study, the thermohydraulic characteristics for the water flow inside a circular pipe enhanced by the twisted conical strip inserts are experimentally assessed. The conical strip inserts are made by stereolithography 3D printer. The effects of geometric features including the twist angle and Pitch Ratio (i.e., the Ratio of Pitch to inner pipe diameter), well as Reynolds number are evaluated. Owing to intensification of the flow mixing and disruption in the boundary layers, the pipe enhanced by the conical inserts has greater friction coefficient and Nusselt number than the smooth pipe. Meanwhile, the Nusselt number and friction coefficient rise by decreasing each of the parameters of twist angle and Pitch Ratio and by increment of the Reynolds number. The Nusselt number increment due to employing the conical inserts is greater at the lower Reynolds numbers. One of the most important causes of the increase in the pressure loss is the existence of dead flow zones behind the conical strip inserts, which these zones decrease by increasing the Pitch Ratio and twist angle. Furthermore, the performance evaluation criterion is greater than 1 for Reynolds numbers of 460 and 630, which indicates that the merit of applying the twisted conical inserts is better in this range of the Reynolds number.
Khashayar Gharagozloo - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of hydrothermal characteristics for flow within a circular tube equipped with twisted conical strip inserts under different alignments
Journal of the Taiwan Institute of Chemical Engineers, 2020Co-Authors: Mehdi Bahiraei, Khashayar GharagozlooAbstract:Abstract This study attempts to experimentally investigate the thermohydraulic characteristics inside a tube fitted with the staggered and non-staggered twisted conical strip inserts. The inserts are built via stereolithography 3D printer. The influences of geometrical attributes such as alignment type (i.e., staggered or non-staggered) and the Pitch Ratio as well as the Reynolds number (Re) on the Nusselt number (Nu) and friction factor (f) are examined. Because of flow mixing and vortex creation in the flow path, the tube fitted with the conical inserts has greater Nu and f in comparison with the smooth tube. The Nu and f have larger amounts in the tube having the non-staggered inserts in comparison with that with the staggered ones. With the Pitch Ratio elevation, the Nu and f diminish, while the elevation in the Re decreases the f and enhances the Nu. Thus, the highest Nusselt number and pressure drop belong to the non-staggered insert with Pitch Ratio of 2.5 and Reynolds number of 2250 with amounts of 15.15 and 795 Pa, respectively. The highest improvement of the Nusselt number in comparison with the plain tube occurs at Reynolds number of 350 for the non-staggered insert with Pitch Ratio of 2.5, which is recorded about 133.8%. Besides, the performance evaluation criterion (PEC) is higher than 1 at Re numbers of 820 and less than 820, which shows the proper merit of applying both the staggered and non-staggered inserts in this Re span. For small Re, the non-staggered inserts lead to larger PEC than the staggered ones, while an opposite outcome is observed for the high Reynolds numbers. The highest PEC is about 1.56, which belongs to the non-staggered alignment with Pitch Ratio of 5 and Reynolds number of 350.
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Experimental study on effect of employing twisted conical strip inserts on thermohydraulic performance considering geometrical parameters
International Journal of Thermal Sciences, 2020Co-Authors: Mehdi Bahiraei, Khashayar Gharagozloo, Hossein MoayediAbstract:Abstract In this study, the thermohydraulic characteristics for the water flow inside a circular pipe enhanced by the twisted conical strip inserts are experimentally assessed. The conical strip inserts are made by stereolithography 3D printer. The effects of geometric features including the twist angle and Pitch Ratio (i.e., the Ratio of Pitch to inner pipe diameter), well as Reynolds number are evaluated. Owing to intensification of the flow mixing and disruption in the boundary layers, the pipe enhanced by the conical inserts has greater friction coefficient and Nusselt number than the smooth pipe. Meanwhile, the Nusselt number and friction coefficient rise by decreasing each of the parameters of twist angle and Pitch Ratio and by increment of the Reynolds number. The Nusselt number increment due to employing the conical inserts is greater at the lower Reynolds numbers. One of the most important causes of the increase in the pressure loss is the existence of dead flow zones behind the conical strip inserts, which these zones decrease by increasing the Pitch Ratio and twist angle. Furthermore, the performance evaluation criterion is greater than 1 for Reynolds numbers of 460 and 630, which indicates that the merit of applying the twisted conical inserts is better in this range of the Reynolds number.
Ahmad Shafee - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of turbulent behavior of nanomaterial exergy loss and flow through a circular channel
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, Fatih Selimefendigil, M M Bhatti, Mehrdad Sheikholeslami, Houman BabazadehAbstract:To understand the impacts of adding twisted tape inside the tube with hybrid nanomaterial, the present paper has been examined with considering FVM. New testing fluid instead of water leads to lower exergy loss. Modeling outputs were carried out for different Pitch Ratio and Reynolds number. Decrement trend for secondary flow was reported when Pitch Ratio increases, and for this reason, convective flow reduces with rise of P which results in greater exergy drop. Turbulence intensity improves with augment of Re which provides stronger interaction of nanomaterial and tube wall. So, thinner boundary layer appears with rise of Re and exergy loss deteriorates.
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Simulation of thermal behavior of hybrid nanomaterial in a tube improved with turbulator
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, Elham Abohamzeh, Nguyen Dang Nam, Iskander TliliAbstract:Simulation of swirl flow intensification with the use of new device inside a pipe was performed in the current investigation. To improve the feature of testing fluid, hybrid nanopowders were dispersed. Outputs were exhibited in terms of contours. Tangential velocity of nanomaterial augments with the increase in Re, and stronger convective mode is obtained with the rise in Re. Thinner thermal boundary layer close to the wall is an output of reducing Pitch Ratio and leads to greater Nu. Augmenting contact surface area with a decline in Pitch Ratio leads to stronger secondary flow.
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Irreversibility of hybrid nanoparticles within a pipe fitted with turbulator
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Ahmad Shafee, M Jafaryar, M Sheikholeslami, Houman BabazadehAbstract:In the current investigation, a novel shape of twisted tape was employed to improve the performance of nanomaterial. Hybrid nanoparticles were dispersed into water, and turbulent flow was considered. Not only the thermal behavior but also the irreversibility should be considered in the design of heat exchanger. Outputs based on FVM simulation are presented in the form of correlations and contours. Increment in efficiency is at a price of higher pressure loss. Pressure drop augments with a reduction in Pitch Ratio, and such behavior makes S _gen,f to augment due to thinner velocity boundary layer. Augmenting the Pitch Ratio causes temperature gradient to reduce; therefore, S _gen,th increases.
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Modeling of heat transfer augmentation due to complex-shaped turbulator using nanofluid
Physica A: Statistical Mechanics and its Applications, 2020Co-Authors: Qingang Xiong, Ahmad Shafee, Mohammad Bagher Ayani, Azeez A. Barzinjy, Rebwar Nasir Dara, Trung Nguyen-thoiAbstract:Abstract To improve the efficiency of pipe, dispersing nanomaterial as well as insertion of turbulator was suggested in current paper. There are three key parameter including, width Ratio (BR), flow rate and Pitch Ratio (PR). Outputs showed that intensity of swirl flow boosts with augmenting width Ratio which provides greater pressure drop. As a pleasant outputs, S g e n , t h declines as BR increases. Nusselt number has descending trend via augmenting Pitch Ratio. Nusselt number tends to augment with width Ratio.
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Design of heat exchanger with combined turbulator
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Truong Khang Nguyen, M Jafaryar, Ahmad Shafee, Mohsen Sheikholeslami, Kotturu V.v. Chandra Mouli, Iskander TliliAbstract:In this article, influence of inserting new turbulator on resistance and heat transfer behaviors of a pipe has been analyzed. This kind of turbulator can be utilized for retrofit applications. Turbulent nanofluid flow is imposed. Homogenous approach for nanofluid and k–ɛ approach for turbulent modeling were involved. Contours are presented for different inlet velocity and Pitch Ratio. Results indicated that the lower the Pitch Ratio, the better is the temperature gradient. Nanofluid transfers more heat with decline of Pitch Ratio because of lower geneRation of longitudinal disturbance. As inlet velocity augments and Pitch Ratio decreases, nanofluid can scour the wall more easily and heat transfer rate is strengthened.
