Analytical Characterization and Production of an Isothermal Surface for Biological and Electronic Applications

Abstract

Characterization and regulation of isothermal surfaces are key issues in a number of thermal management devices. The surface temperature uniformity can be controlled utilizing a variable area channel heat exchanger filled with a porous medium. A comprehensive analytical investigation of forced convection through a generic variable area channel is carried out to design a compact heat exchanger in producing an isothermal surface subject to a constant heat flux, which may be required in the biological, electronics, optical, laser, manufacturing, and solidification applications. Exact solutions for the fluid and solid phases and the wall surface temperature distributions as well as the Nusselt number correlations are established while incorporating local thermal nonequilibrium and transverse conduction contributions. The channel temperature field is adjusted utilizing either an adiabatic or a constant temperature on the inclined surface. The effects of the pertinent physical parameters, such as channel inlet/outlet thickness, inclination angle, Biot number, ratio of fluid and matrix thermal conductivities, working fluid properties, and imposed heat flux, on the fluid and solid temperature fields and the isothermal surface are thoroughly investigated. The results indicate that utilizing proper pertinent parameters, an isothermal surface is achieved. The validity of the utilization of the local thermal equilibrium model is also investigated and error maps are presented.

First and second law analyses of nanofluid forced convection in a partially-filled porous channel – The effects of local thermal non-equilibrium and internal heat sources

“…of Yang and Vafai [46]) are extended to nanofluids. These models describe how heat is distributed between the 6 solid and fluid phases at the porous-fluid interface.…”

“…Model A assumes that total heat flux is the sum of the 7 conductive heat fluxes of either phase at the interface. That is heat division between the two phases according to 8 their effective thermal conductivities and temperature gradients [40,46].…”

Theoretical investigation of entropy generation and heat transfer by forced convection of copper–water nanofluid in a porous channel — Local thermal non-equilibrium and partial filling effects

“…interface model [38,39]. While a number of interface models have been developed, some of them are more 38 widely used [40].…”

Developing convective flow in a square channel partially filled with a high porosity metal foam and rotating in a parallel-mode

“…(12)(13)(14)(15)(16)(17) were discretised and transformed into linear algebraic forms by using the finite volume method. The pressure gradient at the axial direction is decoupled from its gradients at the cross-sectional directions by assuming that the flow is parabolic and employing the solution procedure of Patankar and Spalding [38].…”

“…Due to the significant difference existed between thermal conductivities of metal foams and fluid flowing across them, using the twoequations model for tracking heat transport is indispensable. Many fundamental works were conducted for investigating the influence of both the interfacial surface area and heat transfer coefficient on the heat exchange between the fluid and solid phases in addition to developing a more realistic implementation for thermal boundary conditions at the walls, where valuable and detailed discussions can be found in the analytical works presented by [13][14][15][16][17]. A theoretical model for the effective thermal conductivity of high porosity metal foams was derived by Calmidi and Mahajan [18], where it was matching well with the experimental data obtained for both air and water as a fluid-phase.…”