The Experts below are selected from a list of 3771 Experts worldwide ranked by ideXlab platform
K N Sheeba - One of the best experts on this subject based on the ideXlab platform.
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experimental studies on heat transfer and friction factor characteristics of forced circulation solar water heater system fitted with helical twisted tapes
Solar Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Abstract Experimental investigation of heat transfer, friction factor and thermal performance of twisted tape solar water heater with various twist ratios has been conducted and the results are compared with Plain Tube collector for the same operating conditions with Reynolds number varied from 3000 to 23,000. Experimental data from Plain Tube collector is validated with the fundamental equations and found that the discrepancy is less than ±5.35% and ±8.80% for Nusselt number and friction factor, respectively. Correlations have been developed for Nusselt number and friction factor with various twist ratios ( Y = 3, 4, 5, 6) and are compared with the experimental values. Results conclude that, heat transfer and pressure drop are higher in twisted tape collector compared to the Plain one. Among the various twist ratios, the minimum twist ratio 3 is found to enhance the heat transfer and pressure drop due to swirl generation. As the twist ratio increases, the swirl generation decreases and minimizes the heat transfer and friction factor.
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studies on heat transfer and friction factor characteristics of thermosyphon solar water heating system with helical twisted tapes
Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer, friction factor and thermal performance of thermosyphon solar water heater system fitted with helical twisted tape of various twist ratios has been performed and presented. The helical twisted tape induces swirl flow inside the riser Tubes, which increases the heat transfer and pressure drop. The empirical correlations developed for Nusselt number and friction factor with various twist ratios (Y=3, 4, 5, 6) are fitted with the experimental data with a discrepancy of less than ±4.54% and ±6.13% respectively. The results are compared with a Plain Tube collector at the same operating conditions. Conclusions made from the results show that heat transfer enhancement in twisted tape collector is higher than the Plain Tube collector with minimum twist ratio and gradually decreases with increase in twist ratio. The overall thermal performance of twisted tape collector is found to increase with increase in solar intensity.
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experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of twisted tapes
Applied Thermal Engineering, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system with full- length twist, twist fitted with rod and spacer fitted at the trailing edge for lengths of 100, 200 and 300 mm for twist ratio 3 and 5 has been carried out and compared with Plain Tube collector for the same operating conditions. The experimental data for Nusselt number and friction factor for Plain Tube collector is verified with fundamental equations. Empirical correlations are developed for Nusselt number and friction factor for twist ratio 3 and 5. Results conclude that the decrease in Nusselt number for full length helical twist compared to twist fitted with rod is minimum and is quite significant for twist with spacer. But the decrease in friction factor is maximum in twist fitted with spacer compared to twist fitted with rod. The over all performance for twist fitted with rod is found to be better than twist fitted with spacer.
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Experimental Studies on Heat Transfer and Friction Factor Characteristics of Forced Circulation Solar Water Heater System Fitted with Left-Right Twisted Tapes
International Energy Journal, 2008Co-Authors: S. Jaisankar, T.k. Radhakrishnan, K N SheebaAbstract:Experimental investigation of heat transfer, friction factor and thermal performance of left-right twisted tape solar water heater with various twist ratios have been studied and compared with a Plain Tube collector at the same operating conditions with Reynolds number varied from 3000 to 23000. The empirical correlations developed for Nusselt number and friction factor with various left-right twist ratio(Y= 3, 4, 5, 6) were fitted with the experimental data with in ±15%. Results confirmed that the heat transfer augmentation in left-right twisted tape collector was better than Plain Tube collector. Compared to various twist ratios, heat enhancement and pressure drop were higher with minimum twist ratio, 3. While comparing the absorber plate temperatures for twist and Plain Tube collector, it was found to be minimum for twisted tape collector, because higher heat transfer rate reduces the heat losses and increases the thermal performance.
S Jaisanka - One of the best experts on this subject based on the ideXlab platform.
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experimental studies on heat transfer and friction factor characteristics of forced circulation solar water heater system fitted with helical twisted tapes
Solar Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Abstract Experimental investigation of heat transfer, friction factor and thermal performance of twisted tape solar water heater with various twist ratios has been conducted and the results are compared with Plain Tube collector for the same operating conditions with Reynolds number varied from 3000 to 23,000. Experimental data from Plain Tube collector is validated with the fundamental equations and found that the discrepancy is less than ±5.35% and ±8.80% for Nusselt number and friction factor, respectively. Correlations have been developed for Nusselt number and friction factor with various twist ratios ( Y = 3, 4, 5, 6) and are compared with the experimental values. Results conclude that, heat transfer and pressure drop are higher in twisted tape collector compared to the Plain one. Among the various twist ratios, the minimum twist ratio 3 is found to enhance the heat transfer and pressure drop due to swirl generation. As the twist ratio increases, the swirl generation decreases and minimizes the heat transfer and friction factor.
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studies on heat transfer and friction factor characteristics of thermosyphon solar water heating system with helical twisted tapes
Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer, friction factor and thermal performance of thermosyphon solar water heater system fitted with helical twisted tape of various twist ratios has been performed and presented. The helical twisted tape induces swirl flow inside the riser Tubes, which increases the heat transfer and pressure drop. The empirical correlations developed for Nusselt number and friction factor with various twist ratios (Y=3, 4, 5, 6) are fitted with the experimental data with a discrepancy of less than ±4.54% and ±6.13% respectively. The results are compared with a Plain Tube collector at the same operating conditions. Conclusions made from the results show that heat transfer enhancement in twisted tape collector is higher than the Plain Tube collector with minimum twist ratio and gradually decreases with increase in twist ratio. The overall thermal performance of twisted tape collector is found to increase with increase in solar intensity.
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experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of twisted tapes
Applied Thermal Engineering, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system with full- length twist, twist fitted with rod and spacer fitted at the trailing edge for lengths of 100, 200 and 300 mm for twist ratio 3 and 5 has been carried out and compared with Plain Tube collector for the same operating conditions. The experimental data for Nusselt number and friction factor for Plain Tube collector is verified with fundamental equations. Empirical correlations are developed for Nusselt number and friction factor for twist ratio 3 and 5. Results conclude that the decrease in Nusselt number for full length helical twist compared to twist fitted with rod is minimum and is quite significant for twist with spacer. But the decrease in friction factor is maximum in twist fitted with spacer compared to twist fitted with rod. The over all performance for twist fitted with rod is found to be better than twist fitted with spacer.
T K Radhakrishna - One of the best experts on this subject based on the ideXlab platform.
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experimental studies on heat transfer and friction factor characteristics of forced circulation solar water heater system fitted with helical twisted tapes
Solar Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Abstract Experimental investigation of heat transfer, friction factor and thermal performance of twisted tape solar water heater with various twist ratios has been conducted and the results are compared with Plain Tube collector for the same operating conditions with Reynolds number varied from 3000 to 23,000. Experimental data from Plain Tube collector is validated with the fundamental equations and found that the discrepancy is less than ±5.35% and ±8.80% for Nusselt number and friction factor, respectively. Correlations have been developed for Nusselt number and friction factor with various twist ratios ( Y = 3, 4, 5, 6) and are compared with the experimental values. Results conclude that, heat transfer and pressure drop are higher in twisted tape collector compared to the Plain one. Among the various twist ratios, the minimum twist ratio 3 is found to enhance the heat transfer and pressure drop due to swirl generation. As the twist ratio increases, the swirl generation decreases and minimizes the heat transfer and friction factor.
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studies on heat transfer and friction factor characteristics of thermosyphon solar water heating system with helical twisted tapes
Energy, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer, friction factor and thermal performance of thermosyphon solar water heater system fitted with helical twisted tape of various twist ratios has been performed and presented. The helical twisted tape induces swirl flow inside the riser Tubes, which increases the heat transfer and pressure drop. The empirical correlations developed for Nusselt number and friction factor with various twist ratios (Y=3, 4, 5, 6) are fitted with the experimental data with a discrepancy of less than ±4.54% and ±6.13% respectively. The results are compared with a Plain Tube collector at the same operating conditions. Conclusions made from the results show that heat transfer enhancement in twisted tape collector is higher than the Plain Tube collector with minimum twist ratio and gradually decreases with increase in twist ratio. The overall thermal performance of twisted tape collector is found to increase with increase in solar intensity.
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experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of twisted tapes
Applied Thermal Engineering, 2009Co-Authors: S Jaisanka, T K Radhakrishna, K N SheebaAbstract:Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system with full- length twist, twist fitted with rod and spacer fitted at the trailing edge for lengths of 100, 200 and 300 mm for twist ratio 3 and 5 has been carried out and compared with Plain Tube collector for the same operating conditions. The experimental data for Nusselt number and friction factor for Plain Tube collector is verified with fundamental equations. Empirical correlations are developed for Nusselt number and friction factor for twist ratio 3 and 5. Results conclude that the decrease in Nusselt number for full length helical twist compared to twist fitted with rod is minimum and is quite significant for twist with spacer. But the decrease in friction factor is maximum in twist fitted with spacer compared to twist fitted with rod. The over all performance for twist fitted with rod is found to be better than twist fitted with spacer.
K V Sharma - One of the best experts on this subject based on the ideXlab platform.
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effect of full length twisted tape inserts on heat transfer and friction factor enhancement with fe3o4 magnetic nanofluid inside a Plain Tube an experimental study
International Journal of Heat and Mass Transfer, 2012Co-Authors: Syam L Sunda, N Ravi T Kuma, M T Naik, K V SharmaAbstract:Turbulent convective heat transfer and friction factor characteristics of magnetic Fe3O4 nanofluid flowing through a uniformly heated horizontal circular Tube with and without twisted tape inserts are estimated experimentally. Experiments are conducted in the particle volume concentration range of 0 < u < 0.6%, twisted tape inserts of twist ratio in the range of 0 < H/D < 15and Reynolds number range of 3000 < Re < 22000. Heat transfer and friction factor enhancement of 0.6% volume concentration of Fe3O4 nanofluid in a Plain Tube with twisted tape insert of twist ratio H/D = 5 is 51.88% and 1.231 times compared to water flowing in a Plain Tube under same Reynolds number. Generalized regression equation is presented for the estimation of Nusselt number and friction factor for both water and Fe3O4 nanofluid in a Plain Tube and with twisted tape inserts under turbulent flow condition.
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laminar convective heat transfer and friction factor of al2o3 nanofluid in circular Tube fitted with twisted tape inserts
International Journal of Automotive and Mechanical Engineering, 2011Co-Authors: Syam L Sunda, K V SharmaAbstract:We experimentally investigated the fully developed laminar convective heat transfer and friction factor characteristics of different volume concentrations of Al2O3 nanofluid in a Plain Tube and fitted with different twist ratios of twisted tape inserts. Experiments were conducted with water and nanofluid in the range of 700 Re2200, particle volume concentration of 0.5%, and twisted tape twist ratios of 0H / D15. The nanofluid heat transfer coefficient is high compared to water and further heat transfer enhancement is observed with twisted tape inserts. The pressure drop increases slightly with the inserts, but is comparatively negligible. A generalized regression equation is developed based on the experimental data for the estimation of the Nusselt number and friction factor for water and nanofluid in a Plain Tube and with twisted tape inserts.
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estimation of heat transfer coefficient and friction factor in the transition flow with low volume concentration of al2o3 nanofluid flowing in a circular Tube and with twisted tape insert
International Communications in Heat and Mass Transfer, 2009Co-Authors: K V Sharma, Syam L Sundar, P.k. SarmaAbstract:Experiments to evaluate heat transfer coefficient and friction factor for flow in a Tube and with twisted tape inserts in the transition range of flow with Al2O3 nanofluid are conducted. The results showed considerable enhancement of convective heat transfer with Al2O3 nanofluids compared to flow with water. It is observed that the equation of Gleninski applicable in transitional flow range for single-phase fluids showed considerable deviation when compared with values obtained with nanofluid. The heat transfer coefficient of nanofluid flowing in a Tube with 0.1% volume concentration is 23.7% higher when compared with water at number of 9000. Heat transfer coefficient and pressure drop with nanofluid has been experimentally determined with tapes of different twist ratios and found to deviate with values obtained from equations developed for single-phase flow. A regression equation is developed to estimate the Nusselt number valid for both water and nanofluid flowing in the transition flow Reynolds number range in circular Plain Tube and with tape inserts. The maximum friction factor with twisted tape at 0.1% nanofluid volume concentration is 1.21 times that of water flowing in a Plain Tube.
Agung Tri Wijayanta - One of the best experts on this subject based on the ideXlab platform.
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Double-sided delta-wing tape inserts to enhance convective heat transfer and fluid flow characteristics of a double-pipe heat exchanger
Applied Thermal Engineering, 2018Co-Authors: Agung Tri Wijayanta, Indri Yaningsih, Takahiko Miyazaki, Muhammad Aziz, Shigeru KoyamaAbstract:Abstract One of the challenges in the development of heat exchangers is to minimize their energy consumption. This can be achieved by enhancing the heat transfer rate, which will boost the thermal performance of heat exchangers. Delta-wing vortex generators fitted in a double-pipe heat exchanger will generate vortices with more intermixing of the flowing fluid, and provide the improvement of convective heat transfer of the internal flow. In this study, double-sided delta-wing (T-W) tape inserts were designed to enhance convective heat transfer of a double-pipe heat exchanger. The effects of the wing-width ratio (0.31, 0.47, and 0.63) on the heat transfer and fluid flow characteristics of the heat exchanger were investigated by experiments where water was used as the working fluid and the Reynolds number was varied from 5300 to 14,500. The results were compared with those obtained for a Plain Tube and Tube with longitudinal strip (L-S) insert. The T-W tape insert (wing-width ratio: 0.63) results in the highest average Nusselt number, where the average Nusselt number is higher by 177% relative to that for the Plain Tube. Despite the significant heat transfer enhancement, the friction factor is 11.6 times higher relative to that for the Plain Tube, indicating that friction loss is more pronounced due to the presence of T-Ws. The T-W tape insert (wing-width ratio: 0.63) also results in the highest thermal performance factor (1.15). The Nusselt number, thermal performance factor, and friction factor of the heat exchanger increases as the wing-width ratio of the T-Ws increases. Based on the experimental data, empirical correlations were developed to predict the Nusselt number and friction factor of the double-pipe heat exchanger with T-W tape inserts.
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Impact of Blockage Ratio on Thermal Performance of Delta-Winglet Vortex Generators
MDPI AG, 2018Co-Authors: Indri Yaningsih, Agung Tri Wijayanta, Takahiko Miyazaki, Shigeru KoyamaAbstract:The impact of double-sided delta-winglet tape (DWTs) inserts on convective heat transfer and friction behaviors in a Tube was experimentally investigated. Three DWTs with ratios of winglet-height (b) to inner Tube diameter (di) called blockage ratio (Rb) of 0.28, 0.35 and 0.42 were tested and their performance was compared to that of a longitudinal strip and Plain Tube under similar test flow conditions. Experiments were conducted over a wide range of flow rates, 3.35 × 10−5–8.33 × 10−5 m3/s, which correspond to 5500 ≤ Reynolds number (Re) ≤ 14,500 in the 14.3 mm i.d. Tube. The results revealed that using DWTs dramatically increased the Nusselt number (Nu) by as much as 364.3% and the friction factor (f) by 15.5 times compared with those of a Plain Tube. Thermal performance (η) increased with a corresponding increase in Rb. The highest thermal performance (η) obtained was 1.4. Showing a notable improvement on the thermal performance of the system, DWTs are proposed as a favorable insert device
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heat transfer enhancement of internal flow by inserting punched delta winglet vortex generators with various attack angles
Experimental Thermal and Fluid Science, 2017Co-Authors: Agung Tri Wijayanta, Tri Istanto, Keishi Kariya, Akio MiyaraAbstract:Effects of punched delta winglet vortex generator inserts (PDWVGs) on single-phase forced convection heat transfer and friction loss of internal flow were experimentally investigated. The PDWVGs were manufactured by punching directly on aluminum strips with different attack angles (α) of 30°, 50° and 70°. Winglet-pitch ratio (Rp) and a winglet-width ratio (Rb) of PDWVGs were 1.05 and 0.42, respectively. Longitudinal strip and Plain Tube were also tested for comparison. The experiments were carried out under the conditions of Reynolds number from 5500 to 14500. Experimental results reveal that the PDWVG insert in a Tube provided considerably higher heat transfer coefficient than the Tube without the insert through pressure loss was also increased. The Nusselt number and friction factor increased with the increasing of α. The heat transfer enhancement by the PDWVGs with α of 30°, 50° and 70° provided higher than the Plain Tube in the range of 110–131%, 157–188% and 218–264%, respectively. The average friction factors in the inner Tube generated by the PDWVGs with α of 30°, 50° and 70° were about 8.80, 10.21 and 11.87 times above the Plain Tube, respectively. The thermal enhancement factor was in the range of 0.91–1.22 for PDWVGs and 0.88–0.99 for L-S. In addition, the empirical correlations of Nusselt number, friction factor and thermal performance factor for PDWVGs were developed from the experimental results.
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Influences of pitch-length louvered strip insert on thermal characteristic in concentric pipe heat exchanger
MATEC Web of Conferences, 2017Co-Authors: Indri Yaningsih, Agung Tri WijayantaAbstract:The effects of pitch-length louvered strip inserts with a forward arrangement on heat transfer and friction factor characteristics in a concentric pipe heat exchanger were experimentally investigated. Louvered strip insert was installed inside the Tube. For comparison, the experiment without louvered strip (Plain Tube) was conducted. All cases were tested under steady state condition for Reynolds number ranging from 5300-17,500. The results show that the utilization of louvered strip insert produced a higher heat transfer rate compare to a Plain Tube. Nusselt number, friction factor, and heat transfer coefficient ratio increased with decreasing pitch length. The Nusset number for louvered strip insert with S of 40, 50, and 60 mm increasing in the value of 67% - 77%; 48% - 53%; and 21% - 24% than Plain Tube, respectively. While the Tube fitted with louvered strip insert by S of 40, 50, and 60 mm, friction factor increased 2.91 - 3.84; 2.41 - 2.92; and 1.88 - 2.08 times greater than a Plain Tube. The addition of louvered strip insert with S of 40, 50, and 60 mm producing heat transfer coefficient ratio in the range of 1.02 - 1.12; 1.03 - 1.07 and 1.03 - 1.04.