Ekin ÖZGİRGİN YAPICI, Mahmoud Awni A. Haj IBRAHİM, Haşmet TÜRKOĞLU

BORU YÜZEYİNDEKİ KAPSÜL TİPİ KABARTMANIN VE AL2O3 SU NANOAKIŞKANIN ISI TRANSFERİNE ETKİSİNİN SAYISAL ANALİZİ

Bu çalışmanın amacı, duvar yüzeyinden düzenli ısı akısı uygulanan boru içi akışlarda geometrik modifikasyon yapılarak elde edilecek ısı transferi iyileştirmesinin numerik olarak incelenmesidir. Geometrik modifikasyon olarak kapsül tipi kabartmalar kullanılmış, akışkan olarak ise su ve Al2O3-su nano-akışkan kullanılmıştır. Isı transferi iyileştirmesi için hem geometrik modifikasyon yapılmış olması hem de bununla birlikte farklı yüzdelerde nano-akışkan kullanılmış olması çalışmayı benzerlerinden farklı bir noktaya taşıyabilmektedir. Kapsül tipi kabartmalar borunun iç yüzeyine farklı derinliklerde uygulanmıştır. Al2O3-su nano-akışkan 1%, 2% ve 3% konsantrasyonlarında tek fazlı akış olarak modellenmiş ve uygulanmıştır. Kabartmaların derinliğinin ve nono-akışkanın farklı konsantrasyonlarda uygulamalarının Nusselt sayısı, Sürtünme katsayısı ve Performans Değerlendirme Kriteri (PEC) üzerindeki etkileri çalışılmıştır. Sayısal analizler ANSYS Fluent kullanılarak 2000-14000 Reynolds Sayısı aralığında gerçekleştirilmiştir. Sonuçlar incelendiğinde, tüm akışkanlar için, laminer akış, geçiş akışı ve tamamen gelişmiş türbülanslı akış durumunda kabartma derinliği arttıkça Nusselt Sayısı ve aynı zamanda da sürtünme katsayısının arttığı görülmüştür. Laminer rejimde PEC daki artış etkisi türbülans rejimine göre oldukça fazladır. Performans Değerlendirme Kriterinin değişimi akış rejimine ve kabartma derinliğine oldukça bağlıdır. Genel olarak, laminer akışta nano-akışkan konsantrasyonu ve kabartma derinliği arttıkça Performans Değerlendirme Kriterinin önemli ölçüde arttığı görülmüştür.

Anahtar Kelimeler:

Isı transferi iyileştirmesi, nano-akışkan, kapsül tipi kabartma, sayısal analiz

ANALYSIS OF HEAT TRANSFER ENHANCEMENT IN TUBES WITH CAPSULE DIMPLED SURFACES AND AL2O3-WATER NANOFLUID

This study aims to numerically investigate and evaluate the enhancement of heat transfer by new capsule dimples on tube surfaces for flow of water and Al2O3-water nanofluid with different concentrations, under uniform surface heat flux. The originality of this work lies in combining two passive heat transfer enhancement methods such as geometrical improvements and nanofluids together. Capsule dimples with different depths were considered. Al2O3-water nanofluid was modeled as a single-phase flow based on the mixture properties. The effects of dimple depth and nanoparticle concentrations on Nusselt number, friction factor and performance evaluation criteria (PEC) were studied. Numerical computations were performed using ANSYS Fluent commercial software for 2000 14000 Reynolds number range. It was found that when laminar, transient and fully developed turbulent flow cases are considered, increase in the dimple depth increases the Nusselt number and friction factor for both pure water and Al2O3-water nanofluids cases. Also, the friction factor increases as dimple depth increases. Results show that increase in PEC is more pronounced in the laminar region than in the transition region, it starts to decrease for turbulent flows. For nanofluid, PEC values are considerably higher than pure water cases. The variation of PEC for capsule dimpled tubes are dependent on flow regimes and dimple depths. Increasing the nano particle volume concentration and dimple depth in laminar flows increase the PEC significantly.

Keywords:

Heat transfer enhancement, Nanofluid, capsule dimples, Computational analysis,

PDF

___

Alshehri, F., Goraniya, J., and Combrinck, M. L., 2020, Numerical investigation of heat transfer enhancement of a water/ethylene glycol mixture with Al2O3–TiO2 nanoparticles. Applied Mathematics and Computation, 369, 124836.
Batchelor, G. K., 1977, The effect of Brownian motion on the bulk stress in a suspension of spherical particles. Journal of fluid mechanics, 83(1), 97-117.
Briclot, A., Henry, J. F., Popa, C., Nguyen, C. T. and Fohanno, S., 2020, Experimental investigation of the heat and fluid flow of an Al2O3-water nanofluid in the laminar-turbulent transition region. International Journal of Thermal Sciences, 158, 106546.
Cengel, Y., 2014, Heat and mass transfer: fundamentals and applications. McGraw-Hill Higher Education.
Chandrasekar, M., Suresh, S. and Bose, A. C., 2010, Experimental studies on heat transfer and friction factor characteristics of Al2O3/water nanofluid in a circular pipe under laminar flow with wire coil inserts. Experimental Thermal and Fluid Science, 34 (2), 122-130.
Cheraghi, M. H., Ameri, M. and Shahabadi, M., 2020, Numerical study on the heat transfer enhancement and pressure drop inside deep dimpled tubes. International Journal of Heat and Mass Transfer, 147, 118845.
Chen, J., Müller-Steinhagen, H. and Duffy, G. G., 2001, Heat transfer enhancement in dimpled tubes. Applied thermal engineering, 21 (5), 535-547.
Corcione, M., 2011, Empirical correlating equations for predicting the effective thermal conductivity and dynamic viscosity of nanofluids. Energy Conversion and Management, 52 (1), 789-793.
Eiamsa-Ard, S. and Promvonge, P., 2007, Heat transfer characteristics in a tube fitted with helical screw-tape with/without core-rod inserts. International Communications in Heat and Mass Transfer, 34 (2), 176-185.
Firoozi, A., Majidi, S. and Ameri, M., 2020, A numerical assessment on heat transfer and flow characteristics of nanofluid in tubes enhanced with a variety of dimple configurations. Thermal Science and Engineering Progress, 19, 100578.
Gee, D. L. and Webb, R. L., 1980, Forced convection heat transfer in helically rib-roughened tubes. International Journal of Heat and Mass Transfer, 23 (8), 1127-1136.
Ho, C. J., Chang, C. Y., Yan, W. M. and Amani, P., 2018, A combined numerical and experimental study on the forced convection of Al2O3-water nanofluid in a circular tube. International Journal of Heat and Mass Transfer, 120, 66-75.
Khedkar, R. S., Sonawane, S. S. and Wasewar, K. L., 2014, Heat transfer study on concentric tube heat exchanger using TiO2–water based nanofluid. International communications in Heat and Mass transfer, 57, 163-169.
Kukulka, D. J. and Smith, R., 2013, Thermal-hydraulic performance of Vipertex 1EHT enhanced heat transfer tubes. Applied Thermal Engineering, 61 (1), 60-66.
Kumar, A., Maithani, R. and Suri, A. R. S., 2017, Numerical and experimental investigation of enhancement of heat transfer in dimpled rib heat exchanger tube. Heat and Mass Transfer, 53 (12), 3501-3516.
Liu, B. Y. and Agarwal, J. K., 1974, Experimental observation of aerosol deposition in turbulent flow. Journal of Aerosol Science, 5 (2), 145-155.
Minea, A. A., 2017, Hybrid nanofluids based on Al2O3, TiO2 and SiO2: numerical evaluation of different approaches. International Journal of Heat and Mass Transfer, 104, 852-860.
Ming Li,Tariq S., Khana Ebrahim, Al-HajriaZahid and H.Ayubb, 2016, Single phase heat transfer and pressure drop analysis of a dimpled enhanced tube, Applied Thermal Engineering, 101, 2016, 38-46.
Maxwell, J. C., 1954, Electricity and magnetism (Vol. 2). New York: Dover.
Pak, B. C. and Cho, Y. I., 1998, Hydrodynamic and heat transfer study of dispersed fluids with submicron metallic oxide particles. Experimental Heat Transfer an International Journal, 11 (2), 151-170.
Pathipakka, G. and Sivashanmugam, P., 2010, Heat transfer behavior of nanofluids in a uniformly heated circular tube fitted with helical inserts in laminar flow. Superlattices and Microstructures, 47 (2), 349-360.
Sabir, R., Khan, M. M., Sheikh, N. A., Ahad, I. U. and Brabazon, D., 2020, Assessment of thermo-hydraulic performance of inward dimpled tubes with variation in angular orientations. Applied Thermal Engineering, 170, 115040.
Suresh, S., Chandrasekar, M. and Sekhar, S. C., 2011, Experimental studies on heat transfer and friction factor characteristics of CuO/water nanofluid under turbulent flow in a helically dimpled tube. Experimental Thermal and Fluid Science, 35(3), 542-549.
Tabatabaeikia, S., Mohammed, H. A., Nik-Ghazali, N. and Shahizare, B., 2014, Heat transfer enhancement by using different types of inserts. Advances in Mechanical Engineering, 6, 250354.
Vicente, P. G., Garcı́a, A. and Viedma, A., 2002, Heat transfer and pressure drop for low Reynolds turbulent flow in helically dimpled tubes. International journal of heat and mass transfer, 45 (3), 543-553.
Wang, Y., He, Y. L., Lei, Y. G. and Zhang, J., 2010, Heat transfer and hydrodynamics analysis of a novel dimpled tube. Experimental thermal and fluid science, 34 (8), 1273-1281.
Xuan, Y. and Roetzel, W., 2000, Conceptions for heat transfer correlation of nanofluids. International Journal of heat and Mass transfer, 43 (19), 3701-3707.
Yimin X. and Qiang L., 2000, Heat transfer enhancement of nanofuids, International Journal of Heat and Fluid Flow, 21, 58-64.