Heat transfer with liquid–vapor phase change in microchannels can support very high heat fluxes for use in applications such as the thermal management of high-performance electronics. However, the effects of channel cross-sectional dimensions on the two-phase heat transfer coefficient and pressure drop have not been investigated extensively. In the present work, experiments are conducted to inv...

Shoulder geometry of tool plays an important role in friction-stir welding because it controls thermal interactions and heat generation. This work is proposed and developed a coupled rigid-viscoplastic numerical modeling based on computational fluid dynamics and finite element calculations aiming to understand these interactions. Model solves mass conservation, momentum, and energy equations in...

Helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. In this kind of heat exchangers, flowand heat transfer are complicated. This paper reports a numerical investigation of theinfluence of different parameters such as coil...

in this research a flat plate solar air collector was investigated under direct solar radiation consisted of a slatted glass cover, perforated absorber aluminum sheets (porosity 0.0177, 0.0314 and absorber thickness of 2.5 mm). the effect of porosity on absorber efficiency of collector was evaluated. six levels of air mass flow rates (0.0056 to 0.0385 kg m-2 s-1) were adopted.average solar ener...

This study is concerned with the numerical analysis, formulation, programming and computation of steady, 3D conservation equations of reacting laminar flow heat and mass transfer in ducts of arbitrary cross-sections. The non-orthogonal boundary-fitted coordinate transformation method is applied to the Cartesian form of overall-continuity, momenta, energy and species-continuity equations, parabo...

Thermally-induced changes in heart rate and blood flow in reptiles are believed to be of selective advantage by allowing animal to exert some control over rates of heating and cooling. This notion has become one of the principal paradigms in reptilian thermal physiology. However, the functional significance of changes in heart rate is unclear, because the effect of heart rate and blood flow on ...

The effect of thermal and solutal buoyancy induced by a discrete source of heat and mass transfer in a square duct under the influence of magnetic field, especially at the turbulent regime for the first time is reported. Al2O3/water nanofluid is used with constant heat flux from three discrete heat sources. In the present study, the effects of Reynolds number (100 to 3000), particle volume frac...

An analytical model for a condenser with a wetted surface is developed by applying the governing conservations and rate equations and invoking the heat and mass transfer analogy. The heat exchanger is discretized in both the airflow and refrigerant-flow directions for a cross-flow configuration. Axial conduction along the tube walls is neglected and uniform distribution of water is assumed at t...

This paper reports the numerical determination of the entropy generation due to heat transfer, mass transfer and fluid friction in steady state for laminar double diffusive convection, in an inclined enclosure with heat and mass diffusive walls, by solving numerically the mass, momentum, species conservation and energy balance equations, using a Control Volume FiniteElement Method. The influenc...

the use of solar collectors in combination with heat pipes is rapidly growing in recent years.heat pipes, as heat transfer components, have undeniable advantages in comparison with other alternatives. the most important advantage is their high rate of heat transfer at minor temperature differences. although there have been numerous studies on the heat analysis or first thermodynamic analysis of...