Investigation of air jet impingement drying with forced convection of moist things

Öz

In this work, the effect of drying with jet of air of two dissimilar moist thing geometries with whole and straight semi-circular on the enhancement of heat transfer and decrement of moisture amount was numerically examined. The drying jet had a laminar flow characteristic and two-dimensional jet situated at a fixed jet space from the moist thing. The moist thing diameter, jet space from the moist thing and height of jet initial were taken as stable in whole situations. Streamlines and isotherms were visualized around the things for dissimilar velocities of jet. A method of finite volume was used to figure out the conservation equations by employing software program of ANSYS Fluent 17.0. Computations were conducted for dissimilar Re, so, Re = 100, 200 and 300. It was obtained well accord with scalar and empirical output found in the reference. The results illustrated that the whole circular moist thing had greater good heat and moisture transfer performance than that of the straight semi-circular moist thing. Furthermore, it was seen that an increase of Re number had an affirmative effect on heat and moisture transfer. As locality, drying of jet was appeared to be most powerful close to the stillness point on the front face of the things.

Anahtar Kelimeler

• Forced convection,Moist transfer,Numerical analysis

Nemli nesnelerin zorlanmış taşınım ile hava jeti çarpmalı kurutulmasının incelenmesi

Öz

Bu çalışmada, tam ve düz yarı dairesel olmak üzere iki farklı nemli nesne geometrisinin hava jeti ile kurutulmasının ısı transferi artışı ve nem miktarındaki azalışı üzerindeki etkisi sayısal olarak incelenmiştir. Jet kurutması, nemli nesneden sabit bir jet uzaklığında konumlandırılmış, laminer ve iki boyutludur. Tüm durumlarda, nemli nesnenin çapı, nemli nesneden olan jet uzaklığı ve jet giriş yüksekliği sabit alınmıştır. Farklı jet hızları için nesnelerin etrafındaki akım çizgileri ve eş sıcaklık eğrileri görselleştirilmiştir. Korunum denklemlerini çözmek için sonlu hacim yöntemi olan ANSYS Fluent 17.0 bilgisayar programı kullanılmıştır. Hesaplamalar, Re=100, 200 ve 300 olarak farklı Reynolds sayıları için gerçekleştirilmiştir. Çalışmanın, literatürde var olan sayısal ve deneysel çalışmayla iyi bir uyum içinde olduğu bulunmuştur. Sonuçlar, tam dairesel nemli nesnenin düz yarı dairesel nemli nesneden daha iyi ısı ve nem transferi performansına sahip olduğunu göstermiştir. Ayrıca, Reynolds sayısının artışının ısı ve nem transferi üzerinde olumlu bir etkiye sahip olduğu görülmüştür. Yerel olarak, jet kurutmanın nesnelerin ön taraflarındaki durma noktasına yakın daha etkili oldukları bulunmuştur.

Anahtar Kelimeler

• Zorlanmış taşınım,Nem transferi,Sayısal analiz

Kaynakça

1. Martin H. Heat and Mass Transfer Between Impinging Gas Jets and Solid Surfaces, Advances in Heat Transfer, New York, USA, Academic Press, 1977.
2. Lee HG, Yoon HS, Ha MY. “A numerical investigation on the fluid flow and heat transfer in the confined impinging slot jet in the low reynolds number region for different channel heights”. International Journal of Heat and Mass Transfer, 51(15-16), 4055-4068, 2008.
3. Tawfek AA. “Heat transfer studies of the oblique ımpingement of round jets upon a curved surface”. Heat and Mass Transfer, 38, 467-475, 2002.
4. Olsson EEM, Ahrne LM, Tragardh AC. “Flow and heat transfer from multiple slot air jets impinging on circular cylinders”. Journal of Food Engineering, 67(3), 273-280, 2005.
5. Olsson EEM, Ahrne LM, Tragardh AC. “Heat transfer from a slot air jet impinging on a circular cylinder”. Journal of Food Engineering, 63, 393-401, 2004.
6. Rahman MM, Hernandez CF, Lallave JC. “Free liquid jet impingement from a slot nozzle to a curved plate”. Numerical Heat Transfer Part A, 57(11), 799-821, 2010.
7. Teamah MA, Khairat MM. “Heat transfer due to impinging double free circular jets”. Alexandria Engineering Journal, 54(3), 281-293, 2015.
8. Hosain Md L, Fdhila RB, Daneryd A. “Heat transfer by liquid jets impinging on a hot flat surface”. Applied Energy, 164, 934-943, 2016.

9. McDaniel CS, Webb BW. “Slot jet impingement heat transfer from circular cylinders”. International Journal of Heat and Mass Transfer, 43(11), 1975-1985, 2000.
10. Eren H, Yeşilata B, Celik N. “Nonlinear flow and heat transfer dynamics of impinging jets onto slightly-curved surfaces”. Applied Thermal Engineering, 27(14-15), 2600-2608, 2007.
11. Frost SA, Jambunathan K, Whitney CF, Ball SJ. “Heat transfer from a flat plate to a turbulent axisymmetric impinging jet”. Proceeding of the Institution of Mechanical Engineers, Part C, 211(2), 167-172, 1997.
12. Chan TL, Leung CW, Jambunathan K, Frost SA, Zhou Y, Liu MH. “Heat transfer characteristics of a slot jet impinging on a semi-circular convex surface”. International Journal of Heat and Mass Transfer, 45(5), 993-1006, 2002.
13. Varol Y, Alnak DE, Oztop HF, Al-Salem K. “Numerical analysis of heat transfer due to slot jets impingement onto two cylinders with different diameters”. International Communications in Heat and Mass Transfer, 39(5), 726-735, 2012.
14. Gori F, Petracci I, Tedesco V. “Cooling of two smooth cylinders in row by a slot jet of air with low turbulence”. Applied Thermal Engineering, 27(14-15), 2415-2425, 2007.
15. Chan TL, Zhou Y, Liu M, Leung C. “Mean flow and turbulence measurements of the impingement wall jet on a semi-circular convex surface”. Experiments in Fluids, 34(1), 140-149, 2003.
16. Robinson A, Schnitzler E. “An experimental investigation of free and submerged miniature liquid jet array impingement heat transfer”. Experimental Thermal Fluid Science, 32(1), 1-13, 2007.
17. Tarek JJ, Ray MB. “Application of computational fluid dynamics for simulation of drying processes: a review”. Drying Technology, 28(2), 120-154, 2010.
18. Kaya A, Aydın O, Dincer I. “Numerical modeling of heat and mass transfer during forced convection drying of rectangular moist objects”. International Journal of Heat and Mass Transfer, 49(17-18), 3094-3103, 2006.
19. Alnak DE, Karabulut K. “Analysis of heat and mass transfer of the different moist objects geometries with air slot jet impinging for forced convection drying”. Thermal Science, 22(6B), 2943-2953, 2018.
20. Alnak DE, Varol Y, Oztop HF, Al-Salem K. “Simulation of jet drying of a moist cylinder at low reynolds number”. Drying Technology, 30, 631-640, 2012.
21. Kaya A, Aydın O, Dincer I. “Experimental and numerical ınvestigation of heat and mass transfer during drying of hayward kiwi fruits (actinidia deliciosa planch)”. Journal of Food Engineering, 88(3), 323-330, 2008.
22. Hussain MM, Dincer I. “Two-dimensional heat and moisture transfer analysis of a cylindrical moist object subjected to drying: a finite-difference approach”. International Journal of Heat and Mass Transfer, 46(21), 4033-4039, 2003.
23. Oztop HF, Akpinar EK. “Numerical and experimental analysis of moisture transfer for convective drying of some products”. International Communications in Heat and Mass Transfer, 35(2), 169-177, 2008.
24. Kadem S, Younsi R, Lachemet A. “Computational analysis of heat and mass transfer during microwave drying of timber”. Thermal Science, 20(5), 1447-1455, 2016.
25. Younsi R, Souhila K, Azziz L, Duygu K. “Transient analysis of heat and mass transfer during heat treatment of wood ıncluding pressure equation”. Thermal Science, 19(2), 693-702, 2015.
26. Di Marco P, Frigo S, Gabbrielli R, Pecchia S. “Mathematical modelling and energy performance assessment of air impingement drying system for the production of tissue paper”. Energy, 114, 201-213, 2016.
27. Huang D, Li WF, Shao HJ, Gao AN, Yang XB. “Colour, texture, microstructure and nutrient retention of kiwifruit slices subjected to combined air-impingement jet drying and freeze drying”. International Journal of Food Engineering, 13(7), 2129-2143, 2017.
28. Cemeroğlu B. Meyve Sebze İşleme Teknolojisi 2. 2. Baskı, Ankara, Türkiye, Bizim Grup Basımevi, 2004.
29. Seçkin UG, Taşeri L. “Yarı kurutulmuş meyve sebzeler”. Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi (Pamukkale Gıda Sempozyumu III Özel Sayısı), 21(9), 414-420, 2015.
30. ANSYS Inc., ANSYS FLUENT User's Guide, Fluent, Netherland, Lebanon, ANSYS Press, 2003.