Heat transfer and fluid flow behavior of air in square duct heat exchanger inserted with v-downstream winglet turbulators
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Abstract
This work present the experimental investigation on heat transfer enhancement and thermal performance in a square-duct heat exchanger inserted with 45º V-downstream winglet turbulator is carried out by varying velocity of air in the turbulent regime for Reynolds numbers (Re) ranging from 4000 to 26,000 in the test section with a constant wall heat flux condition. Influents of four different pitch lengths; P=22.5, 33.75, 45 and 90 mm (PR=P/H=0.5, 0.75, 1 and 2) and three different winglet heights, e=6.75, 9 and 11.25 mm (BR=e/H=0.15, 0.2 and 0.25) were inserted diagonally and placed in the core flow area into the test duct on heat transfer rates in the term of Nusselt number (Nu), pressure loss in form of friction factor (f) and thermal performance (). It was found that the 45º V-downstream winglet is provided the Nu and f higher than the smooth surface around 6.0 to 8.7 times and 37 to 170 times, respectively depending upon operating conditions while the thermal performance are about 1.50–2.06. The maximum thermal performance for using 45º V-downstream winglet turbulator is 2.06 at Re=4100, BR=0.2 and PR=1.0 in this experiment.
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[2] Mohsen Sheikholeslami, Mofid Gorji-Bandpy, Davood Domiri Ganji. Review of heat transfer enhancement methods: Focus on passive methods using swirl flow devices. Renewable and Sustainable Energy Reviews. 2015;49: 444–469.
[3] Varun, Saini RP, Singal SK. Investigation of thermal performance of solar air heater having roughness elements as a combination of inclined and transverse ribs on the absorber plate. Renewable Energy. 2008;33(6): 1398–1405.
[4] Zhou G, Ye Q. Experimental investigations of thermal and flow characteristics of curved trapezoidal winglet type vortex generators. Applied Thermal Engineering. 2012;37: 241–248.
[5] Promvonge P, Khanoknaiyakarn C, Kwankaomeng S, C. Thianpong C. Thermal behavior in solar air heater channel fitted with combined rib and delta-winglet. International Communications in Heat and Mass Transfer. 2011;38: 749–756.
[6] Won SY, Ligrani PM. Comparisons of flow structure and local Nusselt numbers in channels with parallel- and crossed-rib turbulators. International Journal of Heat and Mass Transfer. 2004;47: 1573–1586.
[7] Promvonge P, Jedsadaratanachai W, Kwankaomeng S. Numerical study of laminar flow and heat transfer in square channel with 30° inline angled baffle turbulators. Applied Thermal Engineering. 2010;30: 1292–1303.
[8] Promvonge P, Sripattanapipat S, Kwankaomeng S. Laminar periodic flow and heat transfer in square channel with 45° inline baffles on two opposite walls. International Journal of Thermal Sciences. 2010;49: 963–975.
[9] Chokphoemphun S, Chompookham T, Promvonge P. Heat transfer enhancement in a tube heat exchanger with a V-shape winglet turbulator. KKU Research Journal. 2014;19(2): 333–343.
[10] Chokphoemphun S, Pimsarn M, Thianpong C, Promvonge P. Heat transfer augmentation in a circular tube with winglet vortex generators. Chinese Journal of Chemical Engineering. 2015;23: 605–614.
[11] Cengel YA. Heat Transfer: A Practical Approach. 2nd ed. New York: Mc Graw-Hill; 2003.
[12] White FM. Fluid Mechanics. 4th ed. New York: Mc Graw-Hill; 1999.
[13] Webb RL. Principles of Enhanced Heat Transfer. New York: John-Wiley & Sons; 1992.
[14] ASME. Standard measurement of fluid flow in pipes using orifice, nozzle and venture. ASME MFC-3M1984 United Engineering Center 345 East 47th Street. New York: 1-56 1984.
[15] ANSI/ASME. Measurement uncertainty. 1986 PTC 19, Part I, 1-1985 1986
[16] Incropera FP, Witt PD, Bergman TL, Lavine AS. Fundamentals of heat and mass transfer. John-Wiley & Sons; 2006.