Convection In Parallel-plate Channel Research Articles

Forced Convection Heat Transfer Simulation Using Dissipative Particle Dynamics

Dissipative particle dynamics (DPD) with energy conservation was applied to simulate forced convection in parallel-plate channels with boundary conditions of constant wall temperature (CWT) and constant wall heat flux (CHF). DPD is a coarse-grained version of molecular dynamics. An additional equation for energy conservation was solved along with conventional DPD equations, where inter-particle heat flux accounts for changes in mechanical and internal energies when particles interact with surrounding particles. The solution domain was considered to be two–dimensional with periodic boundary condition in the flow direction and additional layers of particles on the top and bottom of the channel to apply no-slip and wall temperature boundary conditions. The governing equation for energy conservation was modified based on periodic fully developed velocity and temperature conditions. The results were shown via velocity and temperature profiles across the channel cross-section. The Nusselt numbers for CWT and CHF were calculated from the temperature gradient at the wall using a second order accurate forward difference approximation. The results agreed well with the exact solutions to within 2.3%.

Forced convection in a channel partly occupied by a bidisperse porous medium: Asymmetric case

This paper presents an analytic investigation of forced convection in parallel-plate channel partly occupied by a bidisperse porous medium and partly by a fluid clear of solid material, the distribution being asymmetrical. The walls of the channel are subject to an uniform heat flux; the flow is assumed to be hydrodynamically and thermally fully developed. The layer of a bidisperse porous medium is attached to one of the channel walls; it is modeled utilizing a two-velocity two-temperature formulation using Darcy’s law. The Beavers–Joseph boundary condition is employed at the bidisperse porous medium/clear fluid interface. The dependences of the Nusselt number on a conductivity ratio, a velocity ratio, a volume fraction, internal heat exchange parameter, and the position of the porous-fluid interface are investigated. Both cases of symmetric and asymmetric heating are investigated, which is specified by the asymmetry heating parameter introduced here. For the case of asymmetric heating, a singular behavior of the Nusselt number is found and explained.

Inverse problem of unsteady conjugated forced convection in parallel plate channels

The heat transfer phenomena of the unsteady laminar forced convection in parallel plate channels with wall conduction effects are still not very well understood. An inverse algorithm based on the conjugate gradient method is proposed to estimate the boundary conditions of these problems, and the minimization of object function is used to reduce the estimated error. The estimation of applied heat flux is found to be highly dependent of temperature sensor location and uncertainty, plate thickness, and heating way. The results show that the predicted boundary conditions by the present inverse method are consistent with the initially specified ones.

Influence of thermal dispersion on forced convection in a composite parallel-plate channel

This paper concentrates on the analytical study of the effect of thermal dispersion on fully developed forced convection in a parallel-plate channel partly filled with a fluid saturated porous medium. The walls of the channel are subject to a constant heat flux. The central part of the channel is occupied by a homogeneous fluid, while peripheral parts of the channel are occupied by a fluid saturated porous medium of uniform porosity. It is assumed that the momentum flow in the porous region is described by the Brinkman-Forchheimer-extended Darcy equation. Since thermal dispersion becomes appreciable in high speed flows, that is, for the same situation when accounting for the Forchheimer term in the momentum equation is essential, the effect of thermal dispersion should be taken into account simultaneously with accounting for the Forchheimer term in the momentum equation. The objective of the present research is to determine in which situations accounting for thermal dispersion can significantly influence the solution.

Hybrid-analytical investigation of unsteady forced convection in parallel-plate channels for thermally developing flow

A theoretical study of unsteady laminar forced convection for a thermally developing flow between parallel plates is presented. A general boundary condition of the fifth kind is used and the flow is subjected to a periodic variation of inlet temperature. To provide hybrid analytical-numerical solution, the generalized integral transform technique is used. The periodic analysis is performed by using two coupled similar problems.

Numerical prediction for laminar forced convection in parallel-plate channels with transverse fin arrays

A numerical study is performed on the laminar forced convection in parallel-plate channels with two series of transverse fins. Velocity and temperature distributions of the periodically fully-developed flow are carried out through a stream function-vorticity transformation with a finite difference scheme. Based on the obtained solutions of flow field, the effect of Reynolds number and other geometric parameters on the heat transfer coefficient and the friction factor can be further evaluated. Results show that the relative position of the fin arrays is an influential factor on the flow field, especially for the higher-fin cases. In general, the in-line arrangement behaves ineffectively due to the remarkable flow recirculation covering the wall surfaces.

Forced convection in parallel-plate channels with a series of fins mounted on the wall

Fluid flow and heat transfer characteristics are analyzed for the laminar forced-convection flows in a parallel-plate channel with an array of fins mounted on the wall. The two plates are maintained at uniform but unequal temperatures and the mounted fins are assumed to be perfectly conductive. Numerical solutions for the Reynolds number within the range 10 ≤ Re ≤ 300, fin height within 0 ≤ e H ≤ 0·5 , and fin pitch within 0 ≤ d H ≤ 4 are presented. Analytical solutions for the infinite and zero pitch cases, representing the lower-bound and upper-bound values, respectively, are developed and compared with the numerical predictions. Results show that both the heat transfer and friction factor (i) increase with the Reynolds number and (ii) are highly sensitive to the geometric arrangements.