Transient natural convection from a finned surface for thermal storage in an enclosure

Journal Article · Mon Jan 01 04:00:00 EST 1996 · Numerical Heat Transfer. Part A, Applications

DOI:https://doi.org/10.1080/10407789608913781· OSTI ID:207732

Benmadda, M; Lacroix, M ^[1]

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1. Univ. de Sherbrooke, Quebec (Canada). Dept. de Genie Mecanique

A numerical study of transient natural convection heat transfer from a finned surface has been conducted for thermal storage in an enclosure. The motivation of this work is found in solar thermal storage tanks. The finned heat exchanging surface provides a means to charge and discharge the thermal energy in the tank. The governing time-dependent conservation equations are solved by a finite difference method. Solutions are obtained for 10{sup 6} {le} Ra {le} 10{sup 8}, for 0--3 fins, for fins of length L/H = 0.3 and 0.75, and for fins parallel and perpendicular to the gravity vector. Results indicate that the storage process is characterized by three distinct heat transfer regimes and that most of the energy is stored during the last regime, referred to as the decay period. The time-changing Nusselt number at the heat exchanging surface is strongly dependent on the Rayleigh number and the number of fins. It is, however, much less sensitive to the size of the fins and their orientation. The storage times are shortened as Ra increases and/or the number of fins and/or their size increases.

• Sponsoring Organization: USDOE
• OSTI ID: 207732
• Journal Information: Numerical Heat Transfer. Part A, Applications, Journal Name: Numerical Heat Transfer. Part A, Applications Journal Issue: 1 Vol. 29; ISSN NHAAES; ISSN 1040-7782
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
25 ENERGY STORAGE
CAVITIES
HEAT STORAGE
NATURAL CONVECTION
NUMERICAL ANALYSIS
SENSIBLE HEAT STORAGE
THERMAL ENERGY STORAGE EQUIPMENT