RESPONSE SURFACE BASED OPTIMIZATION OF RIBBED ISOSCELES TRIANGULAR TWISTED TAPE HEAT EXCHANGER USING ENTROPY AUGMENTATION GENERATION NUMBER WITH AL2O3 NANO WORKING FLUID

Abstract

In this work, a combination of passive techniques like providing ribs on the duct surface, inserting twisted tapes were employed at different configurations and analysed using ANSYS Fluent 17.2. The enhancement is probed by placing ribs on the duct surfaces at various angles. Twisted tape inserts were used in conjunction with ribs on the duct and an output parameter, Entropy Augmentation Generation Number (EAGN) is analysed when having an Al₂O₃ nanofluid (ϕ=3%) as working medium. In furtherance, tapes of isosceles triangular projections with variable configuration, such as rib angles (30⁰<α< 90⁰), Internal angle (30⁰<β<90⁰) and projection distance (1mm< x< 5mm) were also inserted in place of plain twisted tape inserts to verify the enhancement promised by this alteration. As expected, rate of heat transfer due to the presence of isosceles triangle projections gave decent augmentation. Later Response Surface based optimization was employed with non-parametric regression and genetic algorithm to make an investigative search of all the modified parameters so as to suggest best blend of inputs for low Entropy Augmentation Generation Number. Optimum performance was obtained at rib angle of 30⁰, projection distance of 2.1mm and Internal angle of 44.4⁰ with entropy augmentation number value of 0.77. The performance of Genetic Algorithm was compared with Micro Genetic Algorithm; it shows that optimized result is obtained less than half the time using Micro Genetic Algorithm.

Keywords

• Ribs,Isosceles Triangular Projections,Entropy Augmentation Generation Number,Non Parametric Regression,Genetic Algorithm,Micro Genetic Algorithm

References

1. [1] Sarma, P. K., Kishore, P. S., Rao, V. D., Subrahmanyam, T. (2005). A combined approach to predict friction coefficients and convective heat transfer characteristics in A tube with twisted tape inserts for a wide range of Re and Pr. International Journal of Thermal Sciences, 44(4), 393-398.
2. [2] Eiamsa-ard, S., Thianpong, C., Promvonge, P. (2006). Experimental investigation of heat transfer and flow friction in a circular tube fitted with regularly spaced twisted tape elements. International Communications in Heat and Mass Transfer, 33(10), 1225-1233.
3. [3] Eiamsa-Ard, S. (2010). Study on thermal and fluid flow characteristics in turbulent channel flows with multiple twisted tape vortex generators. International Communications in Heat and Mass Transfer, 37(6), 644-651.
4. [4] Eiamsa-Ard, S., 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.
5. [5] Sundar, L. S., Sharma, K. V., & Ramanathan, S. (2007). Experimental investigation of heat transfer enhancements with Al2O3 nanofluid and twisted tape insert in a circular tube. International Journal of Nanotechnology and Applications, 1(2), 21-28.
6. [6] Sivashanmugam, P., Suresh, S. (2007). Experimental studies on heat transfer and friction factor characteristics of turbulent flow through a circular tube fitted with regularly spaced helical screw-tape inserts. Applied Thermal Engineering, 27(8-9), 1311-1319.
7. [7] Eiamsa-ard, S., Pethkool, S., Thianpong, C., & Promvonge, P. (2008). Turbulent flow heat transfer and pressure loss in a double pipe heat exchanger with louvered strip inserts. International Communications in Heat and Mass Transfer, 35(2), 120-129.
8. [8] Kumar, A., Prasad, B. N. (2009). Enhancement in solar water heater performance using twisted tape inserts. National Journal of the Institution of Engineers, 90, 6-9.

9. [9] Al-Fahed, S., Chakroun, W. (1996). Effect of tube-tape clearance on heat transfer for fully developed turbulent flow in a horizontal isothermal tube. International journal of heat and fluid flow, 17(2), 173-178.
10. [10] Eiamsa-ard, S., Thianpong, C., Promvonge, P. (2006). Experimental investigation of heat transfer and flow friction in a circular tube fitted with regularly spaced twisted tape elements. International Communications in Heat and Mass Transfer, 33(10), 1225-1233.
11. [11] Jaisankar, S., Radhakrishnan, T. K., Sheeba, K. N. (2009). Experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of twisted tapes. Applied Thermal Engineering, 29(5-6), 1224-1231.
12. [12] Pramanik D., Saha SK (2006).Thermohydraulics of laminar flowthrough rectangular and square ducts with transverse ribs andtwisted tapes. Trans ASME J Heat Transfer, 128, 1070–1080.
13. [13] Saha, S. K., Dutta, A., Dhal, S. K. (2001). Friction and heat transfer characteristics of laminar swirl flow through a circular tube fitted with regularly spaced twisted-tape elements. International Journal of Heat and Mass Transfer, 44(22), 4211-4223.
14. [14] Saha, S. K., Mallick, D. N. (2005). Heat transfer and pressure drop characteristics of laminar flow in rectangular and square plain ducts and ducts with twisted-tape inserts. Journal of heat transfer, 127(9), 966-977.
15. [15] Pathipakka, G., Sivashanmugam, P. (2010). Heat transfer behaviour of nanofluids in a uniformly heated circular tube fitted with helical inserts in laminar flow. Superlattices and Microstructures, 47(2), 349-360.
16. [16] Nonino, C., Comini, G. (2002). Convective heat transfer in ribbed square channels. International Journal of Numerical Methods for Heat & Fluid Flow, 12(5), 610-628.
17. [17] Konchada, P., Pv, V. Bhemuni, V. (2016). Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach. Archives of Thermodynamics, 37(2), 3-22).
18. [18] Zimparov, V. (2001). Enhancement of heat transfer by a combination of three-start spirally corrugated tubes with a twisted tape. International Journal of Heat and Mass Transfer, 44(3), 551-574.
19. [19] Zimparov, V. (2002). Enhancement of heat transfer by a combination of a single-start spirally corrugated tubes with a twisted tape. Experimental Thermal and Fluid Science, 25(7), 535-546.
20. [20] Bejan A., Pfister P.A. J r (1980). Evaluation of heat transfer augmentation techniques based on their impact on entropy generation.Lett. Heat Mass Transfer, 7, 97–106.
21. [21] Bejan A. (1982).Entropy Generation through Heat and Fluid Flow, Wiley, New York.
22. [22] Hesselgreaves J.E. (2000).Rationalisation of second law analysis of heat exchangers.Internat. J. Heat Mass Transfer, 43, 4189–4204.
23. [23] Zimparov V. (2001). Extended performance evaluation criteria for enhanced heat transfer surfaces: heat transfer through ducts with constant heat flux. International J. Heat Mass Transfer, 44, 169–180.
24. [24] Golberg, D. E. (1989). Genetic algorithms in search, optimization, and machine learning. Addion wesley, 1989(102), 36.
25. [25] D. Whitley (1993). A genetic algorithm tutorial.Colorado State University Technical Report CS-93-103.
26. [26] Razeghi, A., Mirzaee, I., Abbasalizadeh, M. et al. J Braz. Soc. Mech. Sci. Eng. (2017) 39: 2307
27. [27] Al-Rashed , A. , Kolsi , L. , Hussein , A. K. , Hassen , W. , Aichouni , M. and Borjini. (2017). M. Numerical study of three-dimensional natural convection and entropy generation in a cubical cavity with partially active vertical walls , Case Studies in Thermal Engineering , 10,100-110.
28. [28] Kolsi , L. , Hussein, A.K. , Borjini, M. , Mohammed , H. and Ben Aïssia ,H.(2014). Computational analysis of three-dimensional unsteady natural convection and entropy generation in a cubical enclosure filled with water-Al2O3 nanofluid , Arabian Journal for Science and Engineering , 39 ,7483-7493.