Prediction of the Unsteady Turbulent Flow in a Solar Air Heater Test Bench

In this work, the unsteady turbulent flow in a new solar air heater test bench, developed in our LASEM laboratory, was predicted. The considered system consists of two passages solar air heater separated by an absorber and powered by a fan working in a delivery mode, placed in the hole inlet side the insulation. On this system, a glass is hanging on the front side and an absorber is inserted inside. On the glass side, it is connected to the box prototype through a pipe. The hot air flow is routed towards the box prototype. Two circular holes, are located in the same face of the box prototype. The inlet hole allows the hot air supply. However, the outlet hole allows its escape into the ambient environment. By using the ANSYS Fluent 17.0 software, the Navier-Stokes equations coupled with the standard k-ω turbulence model were resolved. The numerical results were compared with our experimental data, established in the second passage of the solar air heater test bench. The good agreement confirms the validity of the numerical method. The range of temperatures is very useful in many applications such as industrial and domestic applications.

Hydromagnetic Heat and Mass Transfer on a Permeable Flat Surface Embedded in a Porous Medium

The steady boundary layer viscous incompressible fluid flow on a permeable flat plate embedded in a porous medium has been considered in the present study. The momentum transport phenomena are subjected to external magnetic field, permeability of the porous medium and cross flow due to presence of suction and injection. Moreover, the heat transfer phenomena consider the loss of thermal energy due to radiation and mass transfer phenomena accounts for the generative/destructive chemical reaction of the reactive species as well. Most importantly, the temperature dependent viscosity and thermal conductivity of the fluid makes the present study more realistic. The numerical solution presented through graphs brings out the interesting outcomes: The higher rate of suction enhances the fluid temperature. This observation is akin to the fact that the higher suction brings the molecules closure hence the heat transfer increases. The porous medium, embedding the plate, acts as a coolant by reducing the fluid temperature.

Diagnosis and Protection of Alternators Against Mass Faults

Generator protection system is one of the complicated industrial systems incorporating many group elements; measurement transformer, relays, circuit breakers and wiring connectors. Generally, protection systems are described using four characteristics; dependability, Sensitivity, rapidity and selectivity. The stator earth fault is a relatively common type of fault. The generators normally have grounded high impedance, that is to say, a ground via a neutral point resistor. This resistance is normally dimensioned to give a ground fault current of the order of 5 to 15 A in the event of permanent earth fault in high voltage terminals of the alternator. Relatively low ground fault currents cause. The new protection technique, it is called an intermittent defect, this type of defect usually has the following characteristics, A very short earth current pulse of high intensity (up to several hundred amps), lasting less than 1 ms. It occurs / disappears automatically over half a period, possibly over several periods, depending on the state of the power grid and the characteristics of the fault. Over longer periods (from several seconds to several minutes), it can evolve into a permanent fault.

Three Dimensional Magnetohydrodynamic Stretched Flow of Cross Nanofluids

The purpose of the present study is to analyze the flow, heat and mass transfer characteristics in the three dimensional magnetohydrodynamic stretched flow of Cross nanofluids. In the present study, Brownian movement, thermophoresis, thermal and solute convective boundary conditions are considered. With boundary layer approximation and self-similarity transformations, the non dimensional nonlinear governing equations are solved via shooting iteration technique together with 4th order Runge-Kutta integration scheme. The impact of developed physical parameters on velocity, temperature, concentration, surface viscous drag, heat and mass transfer rates has been examined via appropriate graphs and discussions. The numerical results indicate that uplift in the magnetic field strength and Weissenberg number diminishes the axial and transverse velocity fields. Further, the temperature ratio parameter brings about substantial improvement to the temperature and the related layer. The outcomes of the present study provide significant contribution to the controlled fluid motion and regulating the rate of heat transportation from the solid boundary into the boundary layer.

Two-Dimensional Flow Through the Uniformly Porous Horizontal Pipe with Thermal Radiation and Cross-Diffusion Effects

This paper is dedicated to the mathematical analysis of an axisymmetric, steady Newtonian fluid flow through a horizontal pipe within the occurrence of radiation, Dufour, and Soret effects. The flow is exposed to associate outwardly functional constant suction above the pipe along Z-direction. The homotopy analysis methodology (HAM) is utilized to get semi-analytical solutions for the coupled differential equations. The results of diverse rising constraints on velocities, thermal and solutal are discussed and pictured. The flow is studied through streamlines, isotherms and pressure contours area unit likewise shown as pictured. It is identified that the temperature can increase with an increase in Dufour parameter but decelerates with an improvement in the radiation parameter. For the given increase within the Soret number, the concentration decelerates.