Salma Parvin

Transient Analysis on Forced Convection Phenomena in a Fluid Valve Using Nanofluid

A transient numerical study is conducted to investigate the transport mechanism of forced convection in a fluid valve filled with water-CuO nanofluid. The flow enters from one inlet at the left with uniform temperature and velocity T i and U i , respectively, but can leave the valve through two outlets at the right. The upper and lower boundaries of the valve are heated with constant temperature T h , while the remaining walls are perfectly insulated. The numerical approach is based on the finite element technique with Galerkins weighted residual simulation. Solutions are obtained for fixed Prandtl number (Pr = 1.47), Reynolds number (Re = 100), and solid volume fraction (φ = 5%). The streamlines, isotherm plots, flow rate and the local Nusselt number (Nu local ) at both heated phases, the average Nusselt number (Nu) for base fluid, and nanofluid with the variation of nondimensional time (τ) are presented and discussed. It is found that the rate of heat transfer in the fluid valve reduces for longer time periods.

Heat Transfer and Collector Efficiency through a Direct Absorption Solar Collector with Radiative Heat Flux Effect

This article presents a numerical visualization of heat transport for forced convective heat transfer by a two-dimensional heat function formulation through a direct absorption solar collector (DASC) filled with water-copper nanofluid. The penalty finite element method is used to solve nonlinear partial differential equations, and the numerical results are presented for variations in the radiative heat flux, Prandtl number, particle diameter, and solid volume fraction of the nanoparticle. The rate of heat transfer, thermal efficiency, mean entropy generation, and Bejan number are strongly dependent on certain parameters. It is observed that the radiative heat flux variation decreases the mean heat transfer, but increases the collector efficiency and entropy generation for nanofluids more than that for pure water. According to the results obtained from this study, under similar operating conditions, DASC is found to have higher efficiency than a flat-plate solar collector (FPSC). Generally, a DASC performs better than a flat-plate collector; however, much better designed flat-plate collectors might be able to match or outperform the efficiency of a nanofluid-based DASC under certain conditions.

Effect of Heat-Generating Solid Body on Mixed Convection Flow in a Ventilated Cavity

The mixed convection flow and heat transfer characteristics inside a square ventilated cavity with a heat-generating solid circular body located at the center have been investigated numerically. The inlet opening is at the bottom of the left wall, while the outlet one is at the top of the right wall, and all the walls of the cavity are considered to be adiabatic. A Galerkin weighted residual finite element method is used to solve the governing equations of mass, momentum, and energy. The behavior of the fluid in the ranges of dimensionless cylinder diameter from 0.1 to 0.6 of the heat generating body, thermal conductivity ratio range from 0.2 to 50 between solid and fluid, and heat generating parameter range from 1 to 5 is described in detail. The medium considered is air with a Prandtl number of 0.71. It is found that the flow and temperature field is strongly dependent on the already-mentioned parameters for the ranges considered. The variation of the mean Nusselt number, the dimensionless average drag force, and the average temperature of the fluid versus Richardson number are presented for these parameters.

Finite element analysis of double-diffusive natural convection in a porous triangular enclosure filled with Al2O3-water nanofluid in presence of heat generation

The problem of double-diffusive natural convection of Al2O3-water nanofluid in a porous triangular enclosure in presence of heat generation has been studied numerically in this paper. The bottom wall of the cavity is heated isothermally, the left inclined wall is non-isothermal and the right inclined wall is considered to be cold. The concentration is higher at bottom wall, lower at right inclined wall and non-isoconcentration at left inclined wall of the cavity. The governing equations are transformed to the dimensionless form and solved numerically using Galerkin weighted residual technique of finite element method. The results are obtained in terms of streamlines, isotherms, isoconcentrations, average Nueeslt number (Nu) and average Sherwood number (Sh) for the parameters thermal Rayleigh number (RaT), dimensionless heat generation parameter (λ), solid volume fraction (ϕ) and Lewis number (Le) while Prandtl number (Pr), Buoyancy ratio (N) and Darcy number (Da) are considered to be fixed. It is observed that flow pattern, temperature fields and concentration fields are affected by the variation of above considered parameters.

Effect of solar irradiation on forced convective heat transfer through a nanofluid based direct absorption solar collector

The present work investigates numerically the convective and radiative heat transfer performance and entropy generation of forced convection through a direct absorption solar collector (DASC). Four different fluids; Cu-water nanofluid, Al2O3-waternanofluid, TiO2-water nanofluid and pure water are used as the working fluid. Entropy production has been taken into account in addition to the collector efficiency and heat transfer enhancement. Penalty finite element method with Galerkin’s weighted residual technique is used to solve the governing non-linear partial differential equations. Numerical simulations are performed for the variation of solar irradiation (I). The outcomes are presented in the form of isotherms, average output temperature, the average Nusselt number, collector efficiency, average entropy generation and Bejan number. The results present that the rate of heat transfer and collector efficiency enhance significantly for raising the values of I upto a certain range.

Natural convective heat and mass transfer in a porous triangular enclosure filled with nanofluid in presence of heat generation

The problem of natural convective heat and mass transfer in a triangular enclosure filled with nanofluid saturated porous medium in presence of heat generation has been studied in this paper. The bottom wall of the cavity is heated uniformly, the left inclined wall is heated linearly and the right inclined wall is considered to be cold. The concentration is higher at bottom wall, lower at right inclined wall and linearly concentrated at left inclined wall of the cavity. The governing equations are transformed to the dimensionless form and solved numerically using Galerkin weighted residual technique of finite element method. The results are obtained in terms of streamline, isotherms, isoconcentrations, Nusselt number (Nu) and Sherwood number (Sh) for the parameters thermal Rayleigh number (RaT), Heat generation parameter (λ) and Lewis number (Le) while Prandtl number (Pr), Buoyancy ratio (N) and Darcy number (Da) are considered to be fixed. It is observed that flow pattern, temperature fields and concentr...