0
Research Papers

Combined Energy and Exergy Analysis of a Nonisothermal Fin Array With Non-Boussinésq Variable Property Fluid

[+] Author and Article Information
Biplab Das

Department of Mechanical Engineering,
National Institute of Technology, Silchar,
Silchar, Assam 788010, India
e-mail: biplab.2kmech@gmail.com

Asis Giri

Department of Mechanical Engineering,
North Eastern Regional Institute of Science
and Technology,
Nirjuli, Arunachal Pradesh 791109, India

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received November 5, 2015; final manuscript received February 19, 2016; published online April 26, 2016. Assoc. Editor: Hongbin Ma.

J. Thermal Sci. Eng. Appl 8(3), 031010 (Apr 26, 2016) (12 pages) Paper No: TSEA-15-1316; doi: 10.1115/1.4033012 History: Received November 05, 2015; Revised February 19, 2016

To transport the energy efficiently without much dissipation, first and second law analyses of mixed convection heat transport from an array of nonisothermal rectangular vertical plate-finned heat sink are made using purely computational fluid dynamics (CFD) analysis on the governing equations. Report provides the dependence of Nusselt number, entropy production, pumping power ratio (PPR), and flow bypass factor (BF) on the inlet velocity, fin conductance parameter, thermal Grashof number (Gr), dimensionless clearance (C*), and dimensionless fin spacing (S*). Total nondimensional entropy production is found to decrease continuously with clearances for all fin spacings, except at the lowest fin spacing involving lowest Gr (= 1.8 × 105). On the other hand, at higher inlet velocities, Nusselt number indicates an optimum value with clearances. Optimum Nusselt number is found to observe in a range of S*= 0.2–0.3 for all Gr. For smaller fin spacing, PPR is noticeably higher, but at the optimum value of fin spacing, PPR reduces roughly by an order of magnitude. Interestingly, flow bypass is remarkably lower at the optimum clearance. Finally, correlation of friction factor, PPR, and entropy generation is presented.

FIGURES IN THIS ARTICLE
<>
Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Prigogine, I. , 1967, Introduction to Thermodynamics of Irreversible Processes, 3rd ed., Wiley, New York.
Bejan, A. , 1982, Entropy Generation Through Heat and Fluid Flow, Wiley, New York.
Bejan, A. , 1996, Entropy Generation Minimization, CRC, Boca Raton, FL.
Bahrehmand, D. , and Ameri, M. , 2015, “ Energy and Exergy Analysis of Different Solar Air Collector Systems With Natural Convection,” Renewable Energy, 74, pp. 357–368. [CrossRef]
Farahat, S. , Sarhaddi, F. , and Ajam, H. , 2009, “ Exergetic Optimization of Flat Plate Solar Collectors,” Renewable Energy, 34(4), pp. 1169–1174. [CrossRef]
Sasikumar, M. , and Balaji, C. , 2002, “ A Holistic Optimization of Convecting-Radiating Fin Systems,” ASME J. Heat Transfer, 124(6), pp. 1110–1116. [CrossRef]
Rakshit, D. , and Balaji, C. , 2005, “ Thermodynamic Optimization of Conjugate Convection From a Finned Channel Using Genetic Algorithms,” Heat Mass Transfer, 41(6), pp. 535–544. [CrossRef]
Shih, C. J. , and Liu, G. C. , 2004, “ Optimal Design Methodology of Plate-Fin Heat Sinks for Electronic Cooling Using Entropy Generation Strategy,” IEEE Trans. Compon. Packag. Technol., 27(3), pp. 551–559. [CrossRef]
Jian-hui, Z. , Chun-xin, Y. , and Li-na, Z. , 2009, “ Minimizing the Entropy Generation Rate of the Plate-Finned Heat Sinks Using Computational Fluid Dynamics and Combined Optimization,” Appl. Therm. Eng., 29(8–9), pp. 1872–1879. [CrossRef]
Iyengar, M. , and Cohen, A. B. , 2002, “ Least-Energy Optimization of Forced Convection Plate-Fin Heat Sinks,” IEEE Trans. Compon. Packag. Techol., 26(1), pp. 62–70.
Culham, J. R. , and Muzychka, Y. S. , 2001, “ Optimization of Plate Fin Heat Sinks Using Entropy Generation Minimization,” IEEE Trans. Compon. Packag. Technol., 24(2), pp. 159–165. [CrossRef]
Andreozzi, A. , Auletta, A. , and Manca, O. , 2006, “ Entropy Generation in Natural Convection in a Symmetrically and Uniformly Heated Vertical Channel,” Int. J. Heat Mass Transfer, 49(17–18), pp. 3221–3228. [CrossRef]
Das, B. , and Giri, A. , 2014, “ Second Law Analysis of an Array of Vertical Plate-Finned Heat Sink Undergoing Mixed Convection,” Int. Commun. Heat Mass Transfer, 56, pp. 42–49. [CrossRef]
Das, B. , and Giri, A. , 2014, “ Non-Boussinésq Laminar Mixed Convection in a Non-Isothermal Fin Array,” Appl. Therm. Eng., 63(1), pp. 447–458. [CrossRef]
Giri, A. , and Das, B. , 2012, “ A Numerical Study of Entry Region Laminar Mixed Convection Over Shrouded Vertical Fin Arrays,” Int. J. Therm. Sci., 60, pp. 212–224. [CrossRef]
Zhang, Z. , and Patankar, S. V. , 1984, “ Influence of Buoyancy on the Vertical Flow and Heat Transfer in a Shrouded Fin Array,” Int. J. Heat Mass Transfer, 27(1), pp. 137–140. [CrossRef]
Al-Sarkhi, A. , Abu-Nada, E. , Akash, B. A. , and Jaber, J. O. , 2003, “ Numerical Investigation of Shrouded Fin Array Under Combined Free and Forced Convection,” Int. Commun. Heat Mass Transfer, 30(3), pp. 435–444. [CrossRef]
Mukhopadhyay, A. , 2010, “ Analysis of Entropy Generation Due to Natural Convection in Square Enclosures With Multiple Discrete Heat Sources,” Int. Commun. Heat Mass Transfer, 37(7), pp. 867–872. [CrossRef]
Patankar, S. V. , 1980, Numerical Heat Transfer and Fluid Flow, Hemisphere, Washington, DC.
Giri, A. , Narasimham, G. S. V. L. , and Murthy, M. V. K. , 2003, “ Combined Natural Convection Heat and Mass Transfer From Vertical Fin Arrays,” Int. J. Heat Fluid Flow, 24(1), pp. 100–113. [CrossRef]
Das, B. , and Giri, A. , 2015, “ Mixed Convection Heat Transfer From a Vertical Fin Array in the Presence of Vortex Generator,” Int. J. Heat Mass Transfer, 82, pp. 26–41. [CrossRef]
Famouri, M. , and Hooman, K. , 2008, “ Entropy Generation for Natural Convection by Heated Partitions in a Cavity,” Int. Commun. Heat Mass Transfer, 35(4), pp. 492–502. [CrossRef]
Daǧtekin, I. , Oztop, H. F. , and Sahin, A. Z. , 2005, “ An Analysis of Entropy Generation Through a Circular Duct With Different Shaped Longitudinal Fins for Laminar Flow,” Int. J. Heat Mass Transfer, 48(1), pp. 171–181. [CrossRef]
Writz, R. A. , Chen, W. , and Zhou, R. , 1994, “ Effect of Flow Bypass on the Performance of Longitudinal Fin Heat Sinks,” ASME J. Electron. Packag., 116(3), pp. 206–211. [CrossRef]
Elshafei, E. A. M. , 2007, “ Effect of Flow Bypass on the Performance of a Shrouded Longitudinal Fin Array,” Appl. Therm. Eng., 27(13), pp. 2233–2242. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

(a) Schematic of mixed convection heat transfer from the vertical plate-finned heat sink and (b) computational domain

Grahic Jump Location
Fig. 2

Local Nusselt number (Nuyz) variation over the fin surface, kfin = 75 W/m K, Gr = 4.3 × 105, Win.mix = 1707, and C*= 0.1: (a) S*= 0.1, (b) S*= 0.2, and (c) S*= 0.3

Grahic Jump Location
Fig. 3

Local Nusselt number (Nuyz) variation over the fin surface, kfin = 150 W/m K, Gr = 4.3 × 105, Win.mix = 1707, and C*= 0.1: (a) S*= 0.1, (b) S*= 0.2, and (c) S*= 0.3

Grahic Jump Location
Fig. 4

Local Nusselt number (Nuyz) variation over the fin surface kfin = 75 W/m K, Gr = 8.4 × 105, Win.mix = 2133, and C*= 0.1: (a) S*= 0.1, (b) S*= 0.2, and (c) S*= 0.3

Grahic Jump Location
Fig. 5

Local Nusselt number (Nuyz) variation along the fin height: (a) S*= 0.1, Z = 1.225 and (b) S*= 0.2 and S*= 0.3, Z = 0.98

Grahic Jump Location
Fig. 6

Development of volumetric rate of local dimensionless entropy generation at different axial locations for kfin = 75 W/m K, Gr = 8.4 × 105, Win,mix = 2400, and T0*  = 3.66. (a) S*= 0.1, Z = 0.029, and C*= 0.05; (b) S*= 0.1, Z = 0.91, and C*= 0.05; (c) S*= 0.1, Z = 4.08, and C*= 0.05; (d) S*= 0.1, Z = 11.36, and C*= 0.05; (e) S*= 0.3, C*= 0.075, and Z = 0.029; (f) S*= 0.3, C*= 0.075, and Z = 0.91; (g) S*= 0.3, C*= 0.075, and Z = 4.08; and (h) S*= 0.3, C*= 0.075, and Z = 11.36.

Grahic Jump Location
Fig. 7

Variation of total dimensionless entropy generation and overall Nusselt number at different inlet mixed convection velocities for T0*  = 3.66 with kfin = 75 W/m K. (a) S*= 0.1, Gr = 1.8 × 105; (b) S*= 0.1, Gr = 8.4 × 105; (c) S*= 0.3, Gr = 1.8 × 105; (d) S*= 0.3, Gr = 8.4 × 105; (e) S*= 0.5, Gr = 1.8 × 105; and (f) S*= 0.5, Gr = 8.4 × 105.

Grahic Jump Location
Fig. 8

Variation of total dimensionless entropy generation and overall Nusselt number at different inlet mixed convection velocities for T0*  = 3.66: (a) kfin = 75 W/m K, Gr = 1.8 × 105, and C*= 0.075 and (b) kfin = 75 W/m K, Gr = 8.4 × 105, and C*= 0.15

Grahic Jump Location
Fig. 9

Correlation of total dimensionless entropy generation with the governing parameters

Grahic Jump Location
Fig. 10

Variation of PPR with clearances for nonisothermal fin, kfin = 75 W/m K, T0*  = 3.66: (a) S*= 0.1, (b) S*= 0.2, (c) S*= 0.3, and (d) S*= 0.5

Grahic Jump Location
Fig. 11

(a) Correlation of PPR with the governing parameters and (b) correlation of friction factor with the governing parameters

Grahic Jump Location
Fig. 12

Axial variation of flow BF, T0*  = 3.66, kfin = 75 W/m K. (a) S*= 0.1, Gr = 8.4 × 105; (b) S*= 0.2, Gr = 8.4 × 105; (c) S*= 0.3, Gr = 8.4 × 105; (d) S*= 0.5, Gr = 8.4 × 105, (e) S*= 0.1, Gr = 4.3 × 105; (f) S*= 0.2, Gr = 4.3 × 105; (g) S*= 0.3, Gr = 4.3 × 105; and (h) S*= 0.5, Gr = 4.3 × 105.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In