Analysis of laminar fully developed mixed convection in a vertical channel with opposing buoyancy

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.2910593· OSTI ID:5274036

Hamadah, T T ^[1]; Wirtz, R A ^[2]

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1. Digital Equipment Corp., Littleton, MA (USA)
2. Univ. of Nevada, Reno (USA)

The problem of laminar fully developed mixed convection in a parallel plate channel is analyzed for the case where buoyancy opposes the flow. Complete, closed-form solutions for the velocity and wall heat transfer are obtained for the following cases: (1) both walls isothermal, with the right wall (Y = 1) at T{sub 2} and the left wall (Y = 0) at T{sub 1} where T{sub 2} > T{sub 1}; (2) both walls at constant heat flux to the fluid, with the right wall q{sub 2}{sup {double prime}} and the left wall at q{sub 1}{sup {double prime}} where q{sub 2}{sup {double prime}} > q{sub 1}{sup {double prime}}; and (3) right wall at constant heat flux, q{sub 2}{sup {double prime}}, while the left wall is maintained at T{sub 1} = T{sub 0}, the fluid inlet temperature. Lavine considered fully developed buoyancy-opposing flow between inclined, constant heat flux plates. Those results, for plates in the vertical orientation, are the same as the present study, Case 2. Kim considered fully developed buoyancy-aided and opposed laminar flow in vertical concentric tube annuli. Closed-form solutions, which can be superimposed to generate any combination of specified heat flux at the inner and outer tube, are presented. Unfortunately solutions for the case where the inner-to-outer tube radius ratio is one (the parallel plate channel) could not be obtained directly. Aung and Worku studied developing and fully developed buoyancy-aided flow between parallel plates with specified plate temperature and heat fluxes. They found that buoyancy enhances heat transfer near the heated wall, and may cause flow reversal near the cooler wall. In the following, solutions to the fully developed flow energy equation are used to obtain the dimensionless velocity profiles in terms of the Grashof-to-Reynolds number ratio. Criteria for the onset of flow reversal are then developed. Expressions for the mean fluid temperature are developed and used to write wall Nusselt number relations.

• OSTI ID: 5274036
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Journal Name: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States) Vol. 113:2; ISSN 0022-1481; ISSN JHTRA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
CALCULATION METHODS
CONVECTION
DUCTS
ENERGY TRANSFER
FLUID FLOW
GRASHOF NUMBER
HEAT TRANSFER
LAMINAR FLOW
MASS TRANSFER
NUSSELT NUMBER
REYNOLDS NUMBER
VELOCITY