Knowledge concerning the complicated changes of mass and heat transfer is desired to improve the performance and durability of unitized regenerative fuel cells (URFCs). In this study, a transient, non-isothermal, single-phase, and multi-physics mathematical model for a URFC based on the proton exchange membrane is generated to investigate transient responses in the process of operation mode swi...

in order to examine the laminar convective heat transfer of nanofluid, experiments carried out using silver-oil nanofluid in a concentric annulus with outer constant heat flux as boundary condition. silver-oil nanofluid prepared by electrical explosion of wire technique and observed no nanoparticles agglomeration during nanofluid preparation process and carried out experiments. the average size...

A new compact analytical model is developed to predict transient heat convection from isoflux vertical plates into a constant property surrounding region. The proposed model is based on a blending of the two asymptotes corresponding to transient diffusion into a half-space and the steady-state convection heat transfer from an isoflux vertical plate. A compact relation for transient and steady-s...

One of the primary ways to enhance heat transfer rate is to use extended surfaces or fins. The heat transfer mechanism of fin is to conduct heat from the heat source to fin surface by its thermal conduction, and then dissipates it to surrounding medium by convection. Most common application areas of fins are in combustion engines, heat exchangers and cooling of electronic equipments. Early stud...

In this paper, the melting of a semi-infinite body as a result of a moving laser beam has been studied. Because the Fourier heat transfer equation at short times and large dimensions does not have sufficient accuracy; a non-Fourier form of heat transfer equation has been used. Due to the fact that the beam is moving in x direction, the temperature distribution and the melting pool shape are not...

A numerical model combining the ultrafast radiative heat transfer and ablation rate equation for free electron density is proposed to investigate the transient process of plasma formation in distilled water. The focused beam propagation governed by the transient equation of radiative heat transfer is solved by the transient discrete ordinates method. The temporal evolution of free electron dens...

Theoretical and experimental study of transient heat transfer parameters related to downward flowing water in a circular concentric annular channel is conducted. The cooling channel is exposed internally to sinusoidal heat flux and has an adiabatic outer surface. The present theoretical study investigated the heat transfer and thermodynamic parameters during of 25%, 50%, and 75% flow reduction ...

In this paper the heat transfer characteristics of a two-phase closed thermosyphon over a wide range of heat transfer rates, system pressure, aspect ratios and filling ratios were studied. The experiments focused on the boiling and condensation heat transfer characteristics of a thermosyphon with a copper tube having 25 and 32 mm inside and outside diameters. Distilled water was used as the wor...