Tek Taraflı Isıtmaya Maruz Yüksek Şekil Oranlı Minikanallarda Pasif Akış Kontrol Yöntemi Kullanılarak Isı Transferinin İyileştirilmesi

Öz

Pasif akış kontrol silindirinin olduğu ve olmadığı durumlarda, bir geniş yüzeyinden ısıtılan dar, dikdörtgen şeklindeki bir minikanal içerisindeki taşınımla ısı transferi durumunun hesaplamalı akışkanlar dinamiği (HAD) benzetiminin sonuçları rapor edilmiştir. Silindirin çapı (d), kanal yüksekliğinin (t) yaklaşık olarak onda biri kadardır. Bu çalışmanın amacı, ısıtılan kanal duvarı ve silindirin merkezi arasındaki üç farklı mesafeyi (s) çalışarak, pasif kontrol silindirinin sistemin ısıl performansı üzerindeki etkisini anlamaktır. Test edilen boyutsuz mesafelere (s/t) bakılmaksızın, pasif kontrol silindirinin mevcudiyetinde sistemin ısıl performansının iyileştiği bulunmuştur. Bu, üniform ısı akısına maruz kalan yüzey üzerindeki hidrodinamik sınır tabaka ile sırayla büyük-ölçekli çevrilere dökülen, silindirden olan serbest kayma tabakalarının şiddetli etkileşimlerine dayandırılmıştır. 

 

Anahtar Kelimeler

• Isı transferi iyileştirilmesi,Pasif akış kontrolü,Minikanal,HAD

Heat Transfer Enhancement in a High Aspect Ratio Minichannel Heated on one Side Using a Passive Flow Control Method

Öz

The results of computational fluid dynamics (CFD) simulation for convective heat transfer in a narrow rectangular minichannel heated on one large side, with and without the presence of passive flow control cylinder, are reported. The diameter of the cylinder (d) is approximately one tenth of the height of the channel (t). The objective of this study is to understand the effect of the passive control cylinder on thermal performance of the system by studying three different distances (s) between the heated channel wall and the center of the cylinder. It was found that the thermal performance of the system enhanced in the presence of the passive control cylinder regardless of non-dimensional distances (s/t) tested. This was attributed to the strong interactions between free shear layers from the cylinder that alternately shed largescale vortices and hydrodynamic boundary layer on the surface that is subjected to a uniform heat flux. 

Anahtar Kelimeler

• Heat transfer enhancement,Passive flow control,Minichannel,CFD

Kaynakça

1. 1. Forrest, E.C., Hu, L.W., Buongiorno, J., McKrell, T.J., 2016. Convective Heat Transfer in a High Aspect Ratio Minichannel Heated on one Side, Journal of Heat Transfer, 138, 021704-1.
2. 2. Bilen, K., Cetin, M., Gul, H., Balta, T., 2009. The Investigation of Groove Geometry Effect on Heat Transfer for Internally Grooved Tubes, Appl. Therm. Eng., 29, 753-761.
3. 3. Webb, R.L., 1981. Performance Evaluation Criteria for Use of Enhanced Heat Transfer Surfaces in Heat Exchanger Design, Int. J. Heat Mass Transf., 24(4), 715-726.
4. 4. Samadifar, M., Toghraie, D., 2018. Numerical Simulation of Heat Transfer Enhancement in a Plate-fin Heat Exchanger Using a New Type of Vortex Generators, Appl. Therm. Eng., 133, 671-681.
5. 5. Promvonge, P., Suwannapan, S., Pimsarn, M., Thianpong, C., 2014. Experimental Study on Heat Transfer in Square Duct with Combined Twisted-tape and Winglet Vortex Generators, Int. Commun. Heat Mass, 59, 158-165.
6. 6. Fluent Inc., 2006. Fluent 6.3 User’s Guide.
7. 7. Dean, R.B., 1978. Reynolds Number Dependence of Skin Friction and Other Bulk Flow Variables in Two-dimensional Rectangular Duct Flow. J. Fluids Engineering, 100, 215-233.
8. 8. Kandlikar, S.G., Grande, W.J., 2003. Evolution of Microchannel Flow Passages- Thermohydraulic Performance and Fabrication Technology. Heat Transfer Eng., 24(1), 3-17.

9. 9. Williamson, C.H.K. 1996. Vortex Dynamics in the Cylinder Wake, 28, 477-539.
10. 10. Liley, P.E., 1984. Steam Tables in SI Units, Private Communication, School of Mechanical Eng., Purdue University, West Lafayette, IN, March 1984.
11. 11. Blasius, H., 1912. Das Aehnlichkeitsgesetz bei Reibungsvorgängen, Z. Ver. Dtsch. Ing., 56(16), 639-643.
12. 12. Colebrook, C.F., 1939. Turbulent Flow in Pipes, with Particular Reference to the Transition Between the Smooth and Rough Pipe Laws, Journal of the Institute of Civil Engineers London, 11, 133–156.
13. 13. Gnielinski, V., 1976. New Equations for Heat and Mass Transfer in Turbulent Pipe and Channel Flow, Int. Chem. Eng., 16(2), 359-368.
14. 14. Petukhov, B.S., 1970. Heat Transfer in Turbulent Pipe Flow with Variable Physical Properties, Adv. Heat Traansfer, 6, 503-564.