Compound Heat Transfer Enhancement in Dimpled and Sinusoidal Metal Solar Wall Ducts Fitted with Wired Inserts
Main Article Content
Abstract
An improved Metal Solar Wall (MSW) with integrated thermal energy storage is presented in this research. The proposed MSW makes use of two, combined, enhanced heat transfer methods. One of the methods is characterized by filling the tested ducts with a commercially available copper Wired Inserts (WI), while the other one uses dimpled or sinusoidal shaped duct walls instead of plane walls. Ducts having square or semi-circular cross sectional areas are tested in this work.
A developed numerical model for simulating the transported thermal energy in MSW is solved by finite difference method. The model is described by system of three governing energy equations. An experimental test rig has been built and six new duct configurations have been fabricated and tested. Air is passed through the six ducts with Reynolds numbers from 1825 to 7300.
Six, new, correlations for Nusselt number and friction factor are developed to assess the benefits that are gained from using the WI and the dimpled and sine-wave duct walls. It is found that higher heat transfer rates are achieved using the Dimpled, semi–circular duct with Wired Inserts (DCWI). Also, it is found that Nusselt number and the pressure drop in the DCWI are respectively
(44.2% -100%) and (101.27% - 172.8%) greater than those of the flat duct with WI. The improvement in Nusselt number for flat duct with WI is found to be (1.4 – 2) times the values for flat duct with no WI. The results demonstrated that DCWI provides enhancements efficiency value that is higher than those obtained from other types of ducts. The developed MSW ducts have added to local knowledge a better understanding of the compound heat transfer enhancement.
Article Details
Section
How to Cite
References
* Aldabbagh a, L.B.Y. Egelioglu a,F. and Ilkan b,M., “Single and Double Pass Solar Air Heaters with Wire Mesh as Packing Bed” ,
Energy ,Vol.36, May 2011.
* Annual Book of ASTM Standards, Vol.04 02 , section E-11, 2004.
* Bhatti, M.S., R.K. Shah, “Turbulent and Transitional Flow Convective Heat Transfer”, Hand book of Single-phase Convection Heat Transfer, John Wiley, NY,1987.
* Bilgen ,E., “Conjugate Heat Transfer by Conduction and Natural Convection on a heated Vertical Walls” ,Applied Thermal Engineering ,Vol.29, 2009.
* Chang,S.W., K.F. Chiang, T.C. Chou, “Heat Transfer and Pressure Drop in Hexagonal Ducts with Surface Dimples”, Exp. Thermal and Fluid Science, Vol. 34, 2010.
* Coutier, J.P. and E.A. Farber, “Designing Rock Beds as Storage Units for Solar Air Systems Using an Optimized Method Based on Numerical Model”, Proceeding of I.S.E.S. Congress, Brighton, England, Aug.1981.
* Dukhan, N. and Kuan-Chih Chen, " Heat Transfer Measurements in Metal Foam Subjected to Constant Heat Flux", Exp. Thermal and Fluid Science, Vol. 32, 2007.
* Durmus ,A., H.Benli , I.Kurtbas and H.Gul ,“Investigation of Heat Transfer and Pressure Drop in plate Heat Exchangers Having Different Surface Profiles ” , Int. J.of Heat and Mass Transfer ,Vol.52, 2009.
* Gnielinski,V., “New Equation for Heat and Mass Transfer in Turbulent Heat Channel Flow”, Int. J. Chem. Eng., Vol.16(2), 1976.
* Jeng, T.M., M.P. Wang, G.J. Hwang and Y.H.Hung, “A New Semi-empirical Model for Predicting Heat Transfer Characteristics in Porous Channels”, Experimental Thermal and Fluid Science, Vol.29, 2004.
* Kline, S. J. and F.A. McClintock, "Describing uncertainties in single sample experiments", Mech. Eng., Vol. 75, 1953.
* Mengna, H., D. Xianhe, H. Kuo and L. Zhiwu, "Compound Heat Transfer Enhancement of a Converging–diverging Tube with Evenly Spaced Twisted-tapes", Chinese Journal of Chemical Eng., Vol.15, 2007.
* Piao,Y, E.G .Hauptmann, and M.Iqbal, “Forced Convection Heat Transfer in cross-corrugated Solar Air Heaters”, J. of Solar Energy Eng., Tr. of ASME , Vol. 116, 1994.
* Pramanik, D. and S. K. Saha, "Thermohydraulics of Laminar Flow Through Rectangular and Square Ducts with Transverse Ribs and Twisted Tapes", J. of Heat Transfer, Tr. of ASME, Vol. 128, 2006.
* Prasad, S.B., J.S. Saini, Krishna M. Singh, “Characteristics of Packed Bed Solar Air Heater Using Wire Mesh Investigation of Heat Transfer and Friction as Packing Material”, Solar Energy, Vol. 83, 2009.
* Promvonge, P., and S. Eiamsa, "Heat Transfer Behaviors in a Tube with Combined Conical-ring and Twisted-tape Insert", Int.Com. in Heat and Mass Tr.,Vol.34, 2007.
* Saini, R.P. and J. Verma, “Heat Transfer and Friction Factor Correlations for a Duct Having Dimple-Shape Artificial Roughness for Solar Air Heaters”, Energy,Vol. 33, 2008.
* Sang Dong Hwang, Hyun Goo Kwon and Hyung Hee Cho, “Heat Transfer with Dimple/Protrusion Arrays in a Rectangular Duct with a Low Reynolds number range”, Int. J. of Heat and Fluid Flow, Vol. 29, 2008
* Stasiek,J.,M.collins, M.Ciofalo,and P.Chew ,“Investigation of Flow and Heat Transfer in Corrugated Passages” , Int. J. Heat Mass
Transfer, Vol.39, 1996.
* Thianpong, C., P. Eiamsa, K. Wongcharee and S. Eiamsa, "Compound Heat Transfer Enhancement of a Dimpled Tube with a
Twisted Tape Swirl Generator", Int. Com.in Heat and Mass Transfer, Vol. 36, 2009.