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Pongjet Promvonge - One of the best experts on this subject based on the ideXlab platform.
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thermal performance enhancement in a heat Exchanger Tube fitted with inclined vortex rings
Applied Thermal Engineering, 2014Co-Authors: Pongjet Promvonge, Narin Koolnapadol, Monsak Pimsarn, Chinaruk ThianpongAbstract:Abstract The influence of inclined vortex rings (VR) on heat transfer augmentation in a uniform heat-fluxed Tube has been investigated experimentally. In the present work, the 30° inclined VRs were mounted repeatedly in the Tube with various geometry parameters of the VR, three relative ring width ratios (BR = b/D = 0.1, 0.15 and 0.2) and four relative ring pitch ratios (PR = P/D = 0.5, 1.0, 1.5 and 2.0). Air was employed as the test fluid in the Tube for the Reynolds number from 5000 to 26,000. The aim at using the VRs is to create counter-rotating vortices inside the Tube to help increase the turbulence intensity as well as to convey the colder fluid from the core regime to the heated-wall region. To find an optimum thermal performance condition, the effect of BR and PR values on the heat transfer and pressure loss in the Tube is examined. The experimental results show a significant effect of the presence of the VRs on the heat transfer and pressure loss over the smooth Tube. The larger BR value provides higher heat transfer and pressure loss than the smaller one while the PR gives an opposite trend. However, the VR at BR = 0.1 and PR = 0.5 yields the best thermal performance.
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effect of perforated twisted tapes with parallel wings on heat tansfer enhancement in a heat Exchanger Tube
Energy Procedia, 2012Co-Authors: C Thianpong, Pongjet Promvonge, P Eiamsaard, Smith EiamsaardAbstract:Abstract This article reports an experimental investigation on heat transfer and pressure drop characteristics of turbulent flow n a heating Tube equipped with perforated twisted tapes with parallel wings (PTT) for Reynolds number between 500 and 20500. The design of PTT involves the following concepts: (1) wings induce an extra turbulence near Tube all and thus efficiently disrupt a thermal boundary layer (2) holes existing along a core Tube, diminish pressure losswithin the Tube. The parameters investigated were the hole diameter ratio (d/W = 0.11, 0.33 and 0.55) and wing depthratio (w/W = 0.11, 0.22 and 0.33). A typical twisted tape was also tested for an assessment. Compared to the plain ube, the Tubes with PTT and TT yielded heat transfer enhancement up to 208% and 190%, respectively. The valuation of overall performance under the same pumping power reveal that the PTT with d/W = 0.11 and w/W = .33, gave the maximum thermal performance factor of 1.32, at Reynolds number of 5500. Empirical correlations of he heat transfer, friction factor and thermal performance for Tubes with PTTs were also developed. In addition, the wirling/axial flow patterns of Tube with PTT were visualized using dye injection technique.
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performance assessment in a heat Exchanger Tube with alternate clockwise and counter clockwise twisted tape inserts
International Journal of Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsaard, Pongjet PromvongeAbstract:Abstract The article presents an experimental study of turbulent heat transfer and flow friction characteristics in a circular Tube equipped with two types of twisted tapes: (1) typical twisted tapes and (2) alternate clockwise and counterclockwise twisted tapes (C–CC twisted tapes). Nine different C–CC twisted tapes are tested in the current work; they included the tapes with three twist ratios, y/w = 3.0, 4.0 and 5.0, each with three twist angles, θ = 30o, 60o and 90o. The experiments have been performed over a Reynolds number range of 3000–27,000 under uniform heat flux conditions, using water as working fluid. The obtained results reveal that the C–CC twisted-tapes provide higher heat transfer rate, friction factor and heat transfer enhancement index than the typical twisted-tapes at similar operating conditions. The results also show that the heat transfer rate of the C–CC tapes increases with the decrease of twist ratio and the increase of twist angle values. Depending on Reynolds number, twist ratio and twist angle values, the mean Nusselt numbers in the Tube fitted with the C–CC twisted tapes are higher than those with the typical ones and the plain Tube around 12.8–41.9% and 27.3–90.5%, respectively. The maximum heat transfer enhancement indexes of the C–CC twisted tapes with θ = 90o for y/w = 3.0, 4.0 and 5.0, are 1.4, 1.34 and 1.3, respectively. In addition, correlations of the Nusselt number and the friction factor for using the C–CC twisted tapes are also determined. Both predicted Nusselt number and friction factor are within ±15% and ±15% deviation compared to the experimental data.
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thermal characteristics in a heat Exchanger Tube fitted with dual twisted tape elements in tandem
International Communications in Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsaard, Chinaruk Thianpong, Petpices Eiamsaard, Pongjet PromvongeAbstract:Abstract The paper presents a comparative investigation of enhanced heat transfer and pressure loss by insertion of single twisted tape, full-length dual and regularly-spaced dual twisted tapes as swirl generators, in a round Tube under axially uniform wall heat flux ( UHF ) conditions. The investigation encompassed the Reynolds number based on the inlet Tube diameter ( D ) ranging from 4000 to 19,000. The experiments are performed using single twisted tapes and full-length dual twisted tapes with three different twist ratios ( y / w = 3.0, 4.0 and 5.0) and also regularly-spaced dual twisted tapes with three different space ratios ( s / D = 0.75, 1.5 and 2.25). The effects of major parameters on heat transfer and friction factor are discussed and the results from both single and dual twisted tape inserts are compared with those from the plain Tube. The result shows that the heat transfer of the Tube with dual twisted tapes is higher than that of the plain Tube with/without single twisted tape insert. For both single twisted tape and full-length dual twisted tapes, Nusselt number ( Nu ) and friction factor ( f ) tend to increase with decreasing twist ratio ( y / w ). The average Nusselt number and friction factor in the Tube fitted with the full-length dual twisted tapes at y / w = 3.0, 4.0 and 5.0, are respectively 146%, 135% and 128%; and 2.56, 2.17 and 1.95 times of those in the plain Tube. For the regularly-spaced dual twisted tapes, the heat transfer rate is decreased with increasing space ratio ( s / D ). The average Nusselt numbers in the Tube fitted with the regularly-spaced dual twisted tapes ( s / D ) of 0.75, 1.5 and 2.25 are respectively, 140%, 137% and 133% of that in the plain Tube. With the similar trend mentioned above, all dual twisted tapes with free spacing yield lower heat transfer enhancement in comparison with the full-length dual twisted tapes ( s / D = 0.0).
Smith Eiamsaard - One of the best experts on this subject based on the ideXlab platform.
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effect of perforated twisted tapes with parallel wings on heat tansfer enhancement in a heat Exchanger Tube
Energy Procedia, 2012Co-Authors: C Thianpong, Pongjet Promvonge, P Eiamsaard, Smith EiamsaardAbstract:Abstract This article reports an experimental investigation on heat transfer and pressure drop characteristics of turbulent flow n a heating Tube equipped with perforated twisted tapes with parallel wings (PTT) for Reynolds number between 500 and 20500. The design of PTT involves the following concepts: (1) wings induce an extra turbulence near Tube all and thus efficiently disrupt a thermal boundary layer (2) holes existing along a core Tube, diminish pressure losswithin the Tube. The parameters investigated were the hole diameter ratio (d/W = 0.11, 0.33 and 0.55) and wing depthratio (w/W = 0.11, 0.22 and 0.33). A typical twisted tape was also tested for an assessment. Compared to the plain ube, the Tubes with PTT and TT yielded heat transfer enhancement up to 208% and 190%, respectively. The valuation of overall performance under the same pumping power reveal that the PTT with d/W = 0.11 and w/W = .33, gave the maximum thermal performance factor of 1.32, at Reynolds number of 5500. Empirical correlations of he heat transfer, friction factor and thermal performance for Tubes with PTTs were also developed. In addition, the wirling/axial flow patterns of Tube with PTT were visualized using dye injection technique.
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experimental investigation of convective heat transfer and pressure loss in a round Tube fitted with circular ring turbulators
International Communications in Heat and Mass Transfer, 2010Co-Authors: Vichan Kongkaitpaiboon, K. Nanan, Smith EiamsaardAbstract:Abstract This paper presents the effect of the circular-ring turbulator (CRT) on the heat transfer and fluid friction characteristics in a heat Exchanger Tube. The experiments were conducted by insertion of CRTs with various geometries, including three different diameter ratios (DR = d/D = 0.5, 0.6 and 0.7) and three different pitch ratios (PR = p/D = 6, 8 and 12). During the test air at 27 °C was passed through the test Tube which was controlled under uniform wall heat flux condition. The Reynolds number was varied from 4000 to 20,000. According to the experimental results, heat transfer rates in the Tube fitted with CRTs are augmented around 57% to 195% compared to that in the plain Tube, depending upon operating conditions. In addition, the results also reveal the CRT with the smallest pitch and diameter ratios offers the highest heat transfer rate in accompany with the largest pressure loss.
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experimental investigation of convective heat transfer and pressure loss in a round Tube fitted with circular ring turbulators
International Communications in Heat and Mass Transfer, 2010Co-Authors: Vichan Kongkaitpaiboon, K. Nanan, Smith EiamsaardAbstract:article i nfo Available online 14 February 2010 This paper presents the effect of the circular-ring turbulator (CRT) on the heat transfer and fluid friction characteristics in a heat Exchanger Tube. The experiments were conducted by insertion of CRTs with various geometries, including three different diameter ratios (DR=d/D=0.5, 0.6 and 0.7) and three different pitch ratios (PR=p/D=6, 8 and 12). During the test air at 27 °C was passed through the test Tube which was controlled under uniform wall heat flux condition. The Reynolds number was varied from 4000 to 20,000. According to the experimental results, heat transfer rates in the Tube fitted with CRTs are augmented around 57% to 195% compared to that in the plain Tube, depending upon operating conditions. In addition, the results also reveal the CRT with the smallest pitch and diameter ratios offers the highest heat transfer rate in accompany with the largest pressure loss.
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performance assessment in a heat Exchanger Tube with alternate clockwise and counter clockwise twisted tape inserts
International Journal of Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsaard, Pongjet PromvongeAbstract:Abstract The article presents an experimental study of turbulent heat transfer and flow friction characteristics in a circular Tube equipped with two types of twisted tapes: (1) typical twisted tapes and (2) alternate clockwise and counterclockwise twisted tapes (C–CC twisted tapes). Nine different C–CC twisted tapes are tested in the current work; they included the tapes with three twist ratios, y/w = 3.0, 4.0 and 5.0, each with three twist angles, θ = 30o, 60o and 90o. The experiments have been performed over a Reynolds number range of 3000–27,000 under uniform heat flux conditions, using water as working fluid. The obtained results reveal that the C–CC twisted-tapes provide higher heat transfer rate, friction factor and heat transfer enhancement index than the typical twisted-tapes at similar operating conditions. The results also show that the heat transfer rate of the C–CC tapes increases with the decrease of twist ratio and the increase of twist angle values. Depending on Reynolds number, twist ratio and twist angle values, the mean Nusselt numbers in the Tube fitted with the C–CC twisted tapes are higher than those with the typical ones and the plain Tube around 12.8–41.9% and 27.3–90.5%, respectively. The maximum heat transfer enhancement indexes of the C–CC twisted tapes with θ = 90o for y/w = 3.0, 4.0 and 5.0, are 1.4, 1.34 and 1.3, respectively. In addition, correlations of the Nusselt number and the friction factor for using the C–CC twisted tapes are also determined. Both predicted Nusselt number and friction factor are within ±15% and ±15% deviation compared to the experimental data.
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thermal characteristics in a heat Exchanger Tube fitted with dual twisted tape elements in tandem
International Communications in Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsaard, Chinaruk Thianpong, Petpices Eiamsaard, Pongjet PromvongeAbstract:Abstract The paper presents a comparative investigation of enhanced heat transfer and pressure loss by insertion of single twisted tape, full-length dual and regularly-spaced dual twisted tapes as swirl generators, in a round Tube under axially uniform wall heat flux ( UHF ) conditions. The investigation encompassed the Reynolds number based on the inlet Tube diameter ( D ) ranging from 4000 to 19,000. The experiments are performed using single twisted tapes and full-length dual twisted tapes with three different twist ratios ( y / w = 3.0, 4.0 and 5.0) and also regularly-spaced dual twisted tapes with three different space ratios ( s / D = 0.75, 1.5 and 2.25). The effects of major parameters on heat transfer and friction factor are discussed and the results from both single and dual twisted tape inserts are compared with those from the plain Tube. The result shows that the heat transfer of the Tube with dual twisted tapes is higher than that of the plain Tube with/without single twisted tape insert. For both single twisted tape and full-length dual twisted tapes, Nusselt number ( Nu ) and friction factor ( f ) tend to increase with decreasing twist ratio ( y / w ). The average Nusselt number and friction factor in the Tube fitted with the full-length dual twisted tapes at y / w = 3.0, 4.0 and 5.0, are respectively 146%, 135% and 128%; and 2.56, 2.17 and 1.95 times of those in the plain Tube. For the regularly-spaced dual twisted tapes, the heat transfer rate is decreased with increasing space ratio ( s / D ). The average Nusselt numbers in the Tube fitted with the regularly-spaced dual twisted tapes ( s / D ) of 0.75, 1.5 and 2.25 are respectively, 140%, 137% and 133% of that in the plain Tube. With the similar trend mentioned above, all dual twisted tapes with free spacing yield lower heat transfer enhancement in comparison with the full-length dual twisted tapes ( s / D = 0.0).
M M K Bhuiya - One of the best experts on this subject based on the ideXlab platform.
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performance assessment in a heat Exchanger Tube fitted with double counter twisted tape inserts
International Communications in Heat and Mass Transfer, 2014Co-Authors: M M K Bhuiya, A S M Sayem, M Islam, M S U Chowdhury, M ShahabuddinAbstract:The present study explored the effects of the double counter twisted tapes on heat transfer and fluid friction characteristics in a heat Exchanger Tube. The double counter twisted tapes were used as counter-swirl flow generators in the test section. The experiments were performed with double counter twisted tapes of four different twist ratios (y = 1.95, 3.85, 5.92 and 7.75) using air as the testing fluid in a circular Tube turbulent flow regime where the Reynolds number was varied from 6950 to 50,050. The experimental results demonstrated that the Nusselt number, friction factor and thermal enhancement efficiency were increased with decreasing twist ratio. The results also revealed that the heat transfer rate in the Tube fitted with double counter twisted tape was significantly increased with corresponding increase in pressure drop. In the range of the present work, heat transfer rate and friction factor were obtained to be around 60 to 240% and 91 to 286% higher than those of the plain Tube values, respectively. The maximum thermal enhancement efficiency of 1.34 was achieved by the use of double counter twisted tapes at constant blower power. In addition, the empirical correlations for the Nusselt number, friction factor and thermal enhancement efficiency were also developed, based on the experimental data.
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thermal characteristics in a heat Exchanger Tube fitted with triple twisted tape inserts
International Communications in Heat and Mass Transfer, 2013Co-Authors: M M K Bhuiya, M S U Chowdhury, M Shahabuddin, Manabendra Saha, L A MemonAbstract:Abstract In the present study, the influences of triple twisted tapes on heat transfer rate, friction factor and thermal enhancement efficiency were experimentally investigated. The triple twisted tapes were used as swirl flow generators in the test section. The investigations were conducted using the mild steel triple twisted tapes with four different twist ratios ( y = 1.92, 2.88, 4.81 and 6.79) for Reynolds number ranging from 7200 to 50,200 under uniform heat flux condition. The experimental results demonstrated that the Nusselt number, friction factor and thermal enhancement efficiency increased with decreasing twist ratio. The results indicated that the presence of triple twisted tapes led to a higher increase in the heat transfer rate over the plain Tube. The Nusselt number and friction factor of using the triple twisted tape inserts were found to be increased up to 3.85 and 4.2 times when compared with the plain Tube, respectively. The heat transfer performance was evaluated based on the constant blower power and the performance was achieved to be 1.44 by the use of triple twisted tape inserts. Finally, correlations were developed based on the data gathered during this work for predicting the heat transfer, friction factor and thermal enhancement efficiency through a circular Tube fitted with triple twisted tape inserts in terms of twist ratio ( y ), Reynolds number (Re) and Prandtl number (Pr).
Chinaruk Thianpong - One of the best experts on this subject based on the ideXlab platform.
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Flow and thermal mechanisms in a heat Exchanger Tube inserted with twisted cross-baffle turbulators
Applied Thermal Engineering, 2017Co-Authors: K. Nanan, Monsak Pimsarn, Chinaruk Thianpong, V. Chuwattanakul, Smith Eiamsa-ardAbstract:Abstract The turbulent forced convective heat transfer behaviors in a Tube inserted with baffle turbulators (typical straight baffles, straight cross-baffles, straight alternate-baffles, twisted-baffles, alternate twisted-baffles, and twisted cross-baffles) have been experimentally and numerically investigated. The influence of pitch ratio (P/D) from 1.0 to 2.0 and Reynolds numbers (Re) from 6000 to 20,000 are also reported. Among the studied turbulators, the twisted cross-baffles gave the highest heat transfer enhancement and thermal enhancement factor while the straight cross-baffles gave the lowest heat transfer rate and thermal enhancement factor. The twisted-baffles, alternate twisted-baffles, and twisted cross-baffles created high longitudinal vortex/swirl around the Tube core. The strongest longitudinal vortex/swirl was achieved by the use of twisted cross-baffles. The recirculation flows were found in the Tube fitted with straight baffles (a recirculation flow), straight alternate-baffles (double recirculation flows) and straight cross-baffles (quadruple recirculation flows). The heat transfer rate, friction factor and thermal enhancement factor increased with decreasing pitch ratio (P/D) and increasing Reynolds number (Re). At the optimum condition of the smallest pitch ratio (P/D = 1.0) and the lowest Reynolds number (Re = 6000), the twisted cross-baffles offered the highest thermal enhancement factor of 1.7.
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thermal performance enhancement in a heat Exchanger Tube fitted with inclined vortex rings
Applied Thermal Engineering, 2014Co-Authors: Pongjet Promvonge, Narin Koolnapadol, Monsak Pimsarn, Chinaruk ThianpongAbstract:Abstract The influence of inclined vortex rings (VR) on heat transfer augmentation in a uniform heat-fluxed Tube has been investigated experimentally. In the present work, the 30° inclined VRs were mounted repeatedly in the Tube with various geometry parameters of the VR, three relative ring width ratios (BR = b/D = 0.1, 0.15 and 0.2) and four relative ring pitch ratios (PR = P/D = 0.5, 1.0, 1.5 and 2.0). Air was employed as the test fluid in the Tube for the Reynolds number from 5000 to 26,000. The aim at using the VRs is to create counter-rotating vortices inside the Tube to help increase the turbulence intensity as well as to convey the colder fluid from the core regime to the heated-wall region. To find an optimum thermal performance condition, the effect of BR and PR values on the heat transfer and pressure loss in the Tube is examined. The experimental results show a significant effect of the presence of the VRs on the heat transfer and pressure loss over the smooth Tube. The larger BR value provides higher heat transfer and pressure loss than the smaller one while the PR gives an opposite trend. However, the VR at BR = 0.1 and PR = 0.5 yields the best thermal performance.
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Heat transfer and thermal performance characteristics of heat Exchanger Tube fitted with perforated twisted-tapes
Heat and Mass Transfer, 2012Co-Authors: Chinaruk Thianpong, Petpices Eiamsa-ard, Smith Eiamsa-ardAbstract:Twisted tape insert was applied as a swirling flow generator for the passive heat transfer enhancement in the present work. The influences of the perforated twisted tapes (PTs) on the heat transfer, pressure loss and thermal performance characteristics were investigated experimentally. The experiments were performed under uniform wall heat flux condition by using PTs with y/W = 3, 4 and 5, d/W = 0.11, 0.14 and 0.17 and s/W = 0.4, 0.6 and 0.8 where y is a twist length, d is a perforation hole diameter, s is a spacing between holes (pitch) and W is a tape width. The experimental results reveal that Nusselt number increased with decreasing s/W and y/W and increasing d/W . For the present range, the maximum heat transfer was obtained by utilizing the tape with s/W = 0.4, d/W = 0.17 and y/W = 3, which is higher than those obtained from the plain Tube with and without typical twisted tape by around 27.4 and 86.7%, respectively. In addition, the empirical correlations for Nusselt number, friction factor and thermal performance are also proposed in the present paper.
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thermal characteristics in a heat Exchanger Tube fitted with dual twisted tape elements in tandem
International Communications in Heat and Mass Transfer, 2010Co-Authors: Smith Eiamsaard, Chinaruk Thianpong, Petpices Eiamsaard, Pongjet PromvongeAbstract:Abstract The paper presents a comparative investigation of enhanced heat transfer and pressure loss by insertion of single twisted tape, full-length dual and regularly-spaced dual twisted tapes as swirl generators, in a round Tube under axially uniform wall heat flux ( UHF ) conditions. The investigation encompassed the Reynolds number based on the inlet Tube diameter ( D ) ranging from 4000 to 19,000. The experiments are performed using single twisted tapes and full-length dual twisted tapes with three different twist ratios ( y / w = 3.0, 4.0 and 5.0) and also regularly-spaced dual twisted tapes with three different space ratios ( s / D = 0.75, 1.5 and 2.25). The effects of major parameters on heat transfer and friction factor are discussed and the results from both single and dual twisted tape inserts are compared with those from the plain Tube. The result shows that the heat transfer of the Tube with dual twisted tapes is higher than that of the plain Tube with/without single twisted tape insert. For both single twisted tape and full-length dual twisted tapes, Nusselt number ( Nu ) and friction factor ( f ) tend to increase with decreasing twist ratio ( y / w ). The average Nusselt number and friction factor in the Tube fitted with the full-length dual twisted tapes at y / w = 3.0, 4.0 and 5.0, are respectively 146%, 135% and 128%; and 2.56, 2.17 and 1.95 times of those in the plain Tube. For the regularly-spaced dual twisted tapes, the heat transfer rate is decreased with increasing space ratio ( s / D ). The average Nusselt numbers in the Tube fitted with the regularly-spaced dual twisted tapes ( s / D ) of 0.75, 1.5 and 2.25 are respectively, 140%, 137% and 133% of that in the plain Tube. With the similar trend mentioned above, all dual twisted tapes with free spacing yield lower heat transfer enhancement in comparison with the full-length dual twisted tapes ( s / D = 0.0).
M Shahabuddin - One of the best experts on this subject based on the ideXlab platform.
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performance assessment in a heat Exchanger Tube fitted with double counter twisted tape inserts
International Communications in Heat and Mass Transfer, 2014Co-Authors: M M K Bhuiya, A S M Sayem, M Islam, M S U Chowdhury, M ShahabuddinAbstract:The present study explored the effects of the double counter twisted tapes on heat transfer and fluid friction characteristics in a heat Exchanger Tube. The double counter twisted tapes were used as counter-swirl flow generators in the test section. The experiments were performed with double counter twisted tapes of four different twist ratios (y = 1.95, 3.85, 5.92 and 7.75) using air as the testing fluid in a circular Tube turbulent flow regime where the Reynolds number was varied from 6950 to 50,050. The experimental results demonstrated that the Nusselt number, friction factor and thermal enhancement efficiency were increased with decreasing twist ratio. The results also revealed that the heat transfer rate in the Tube fitted with double counter twisted tape was significantly increased with corresponding increase in pressure drop. In the range of the present work, heat transfer rate and friction factor were obtained to be around 60 to 240% and 91 to 286% higher than those of the plain Tube values, respectively. The maximum thermal enhancement efficiency of 1.34 was achieved by the use of double counter twisted tapes at constant blower power. In addition, the empirical correlations for the Nusselt number, friction factor and thermal enhancement efficiency were also developed, based on the experimental data.
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thermal characteristics in a heat Exchanger Tube fitted with triple twisted tape inserts
International Communications in Heat and Mass Transfer, 2013Co-Authors: M M K Bhuiya, M S U Chowdhury, M Shahabuddin, Manabendra Saha, L A MemonAbstract:Abstract In the present study, the influences of triple twisted tapes on heat transfer rate, friction factor and thermal enhancement efficiency were experimentally investigated. The triple twisted tapes were used as swirl flow generators in the test section. The investigations were conducted using the mild steel triple twisted tapes with four different twist ratios ( y = 1.92, 2.88, 4.81 and 6.79) for Reynolds number ranging from 7200 to 50,200 under uniform heat flux condition. The experimental results demonstrated that the Nusselt number, friction factor and thermal enhancement efficiency increased with decreasing twist ratio. The results indicated that the presence of triple twisted tapes led to a higher increase in the heat transfer rate over the plain Tube. The Nusselt number and friction factor of using the triple twisted tape inserts were found to be increased up to 3.85 and 4.2 times when compared with the plain Tube, respectively. The heat transfer performance was evaluated based on the constant blower power and the performance was achieved to be 1.44 by the use of triple twisted tape inserts. Finally, correlations were developed based on the data gathered during this work for predicting the heat transfer, friction factor and thermal enhancement efficiency through a circular Tube fitted with triple twisted tape inserts in terms of twist ratio ( y ), Reynolds number (Re) and Prandtl number (Pr).
