Conjugate heat transfer in an inclined slab with an array of horizontal circular channels

Journal Article · Fri May 28 04:00:00 EDT 1999 · Numerical Heat Transfer. Part A, Applications

OSTI ID:355625

Cheng, C H; Yu, J H ^[1]

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1. Tatung Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

Effects of buoyancy on thermal characteristics of conjugate heat transfer across an inclined slab with an array of horizontal, circular channels inside are investigated numerically. Results are presented for Prandtl numbers of 0.7 and 4 over wide ranges of values of Grashof number Gr and thermal conductivity ratio, with the angle of inclination {phi} ranging from 0{degree} to 180{degree} from the horizontal. It is found that higher heat transfer rates can be obtained when the slab is inclined with {phi} = 60--90. For some particular cases, a 30% increase in heat transfer, but only 8% increase in friction factor, may be obtained by changing the inclination angle. In general, the secondary fluid flow exhibits a single-cell pattern in the channel within the inclined slab with the exception of the cases at {phi} = 180{degree} and 0{degree}. For {phi} = 180{degree} (hot top) and {phi} = 0{degree} (hot bottom), a symmetric four-cell secondary flow pattern may be observed at lower Gr. However, for the hot-bottom cases, when Gr exceeds a threshold value, the secondary flow resumes the single-cell patterns and a significant increase in the Nusselt number is clearly observed. For the parameter ranges considered in this study, the threshold value is located within Gr = 10{sup 4}--10{sup 5}, dependent on the physical and geometric parameters. During the past several decades, heat transfer behavior of inclined thermal devices has been an interesting topic to researchers involved with heat exchangers, solar collectors, electronic cooling systems, cooling systems of die casting molds, etc.

• Sponsoring Organization: National Science Council, Taipei (Taiwan, Province of China)
• OSTI ID: 355625
• Journal Information: Numerical Heat Transfer. Part A, Applications, Journal Name: Numerical Heat Transfer. Part A, Applications Journal Issue: 7 Vol. 35; ISSN 1040-7782; ISSN NHAAES
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
FRICTION FACTOR
HEAT TRANSFER
INCLINATION
NUMERICAL ANALYSIS
SLABS
USES