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Research Papers: Forced Convection

Croce Giulio, Rovenskaya Olga, D'Agaro Paola. Computational Analysis of Conjugate Heat Transfer in Gaseous Microchannels J. Heat Transfer 137(4), 041701 (2015) (7 pages);   Paper No: HT-13-1506;   doi:10.1115/1.4029259

A fully conjugate heat transfer analysis of gaseous flow in short microchannels is presented. Navier–Stokes equations, coupled with Maxwell and Smoluchowski slip and temperature jump boundary conditions, are used for numerical analysis. Results are presented in terms of Nusselt number, heat sink thermal resistance, and resulting wall temperature as well as Mach number profiles for different flow conditions. The comparative importance of wall conduction, rarefaction, and compressibility are discussed. It was found that compressibility plays a major role. Although a significant penalization in the Nusselt number, due to conjugate heat transfer effect, is observed even for a small value of solid conductivity, the performances in terms of heat sink efficiency are essentially a function only of the Mach number.

Technical Brief

Wang Xiaowu, Li Yaochao, Wan Zhenpin. Thermal Conduction Performance of Fiber-Enhanced Polyalcohol Binary Systems J. Heat Transfer 137(4), 044501 (2015) (4 pages);   Paper No: HT-14-1128;   doi:10.1115/1.4029269

Polyalcohol has poor heat conduction performance. A fiber-enhanced polyalcohol binary system combines polyalcohol with a copper fiber net to improve its heat conduction performance. In a binary system without fibers, more heat input increases the wall temperature near the container than when the fiber is present. Compared to a polyalcohol binary system, pentaerythritol/Tris hydroxymethyl aminomethane (PE/TRIS) without fibers, fiber-enhanced polyalcohol system PE/TRIS shows quicker response to energy input from the exterior region. The phase change temperature in a fiber-enhanced polyalcohol binary system is much lower than that in a polyalcohol system without fibers. This is because of the metastate plastic state that presents a nonfaceted phase interface with a larger radius of curvature in a polyalcohol system without fibers. The porous structure of the fiber is smaller than the size of the phase interface in a polyalcohol system without fibers and can increase the equilibrium pressure and make the phase change easier.

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