The electrical and thermal performances of photovoltaic thermal (PVT) water collectors were determined under 500–800 W/m solar radiation levels. At each solar radiation level, mass flow rates ranging from 0.011 kg/s to 0.041 kg/s were introduced. The PVT collectors were tested with respect to PV efficiency, thermal efficiency, and a combination of both (PVT efficiency). The results show that th...

In this paper the linear theory of nonequilibrium thermodynamics, developed by Onsager and others, is applied to random networks with arbitrary degree distribution. Using the well-known methods of nonequilibrium thermodynamics we identify thermodynamic forces and their conjugated flows induced in networks as a result of single node degree perturbation. The forces and the flows can be understood...

Thermal accommodation coefficient, one of the fundamental parameters in rarefied gas dynamics, is usually introduced to account for the fraction of incident molecules interacting with solid surface in a diffusive manner. In the present study, the effects of thermal accommodation on the unsteady one-dimensional micro-flow are examined, when the oscillating flow input is applied, by employing the...

Heat and mass transfer, in this paper, is considered in one-row heat exchanger, that fins are hotter than air flow and water is added to fins. Related governing equations are derived by analyzing a two-dimension model in a unique cell of a heat exchange. These equations are numerically solved by finite difference method. Heat transfer and efficiency under partially wet surface are calculated by...

This study numerically investigated heat transfer and fluid flow characteristics in a novel cylindrical heat sink with helical minichannels for the laminar flow of fluid with temperature-dependent properties. A finite volume method was employed to obtain the solution of governing equations. The effects of helical angle, channel aspect ratio, and Reynolds number, which were regarded as main para...

The present paper focuses on problem of mixed convection fluid flow and heat transfer of Al2O3-water nanofluid with temperature and nanoparticles concentration dependent thermal conductivity and effective viscosity inside Lid-driven cavity having a hot rectangular obstacle. The governing equations are discretized using the finite volume method while the SIMPLER algorithm is employed to couple v...

In this paper, the magnetohydrodynamic (MHD) axisymmetric stagnation-point flow of an unsteady and electrically conducting incompressible viscous fluid in with temperature dependent thermal conductivity, thermal radiation and Navier slip is investigated. The flow is due to a shrinking surface that is shrunk axisymmetrically in its own plane with a linear velocity. The magnetic field is imposed ...

This article is proposed to address the melting heat transfer of a Jeffrey fluid in Blasius and Sakiadis flow caused due to a moving surface. Thermal radiation and a constant free stream are considered in this mathematical model. The non-linear coupled dimensionless equations from the governing equations are attained by employing appropriate similarity transformations. The resulting dimensionle...

Present study explores the effect of Hall current, non-linear radiation, irregular heat source/sink on magnetohydrodynamic flow of Casson nanofluid past a nonlinear stretching sheet. Viscous and Joule dissipation are incorporated in the energy equation. An accurate numerical solution of highly nonlinear partial differential equations, describing the flow, heat and mass transfer...

The combined effects of mass transfer and rotation on unsteady magnetohydrodynamic (MHD) free convection flow in a porous medium past an infinite inclined plate with ramped wall temperature has been investigated. The effects of thermal diffusion and heat absorption are also observed. Exact solution using Laplace transforms technique has been obtained for the velocity, temperature and concentrat...