Two-phase numerical simulation of nanofluid laminar convection heat transfer through Flat-plate solar collector

Abstract

Scarcity and continuous depletion of conventional energy sources gradually making renewable energy especially solar energy as an alternative energy source. One of the simplest and most direct applications of this energy is the conversion of solar radiation into heat, which can be used in water heating systems. A commonly used solar collector is the flat-plate collector. The objective of this thesis work is to investigate the heat transfer performance of nanofluid in solar collector and due to this purpose heat transfer coefficient of nanofluid, amount of heat transfer and average Nusselt number at various volume concentrations and Reynolds number were studied. Numerical simulation of Al2O3/water nanofluid was carried out using ANSYS-FLUENT 14.0 CFD package. This thesis deals with the convection of water and nanofluid in flat plate solar collector under steady laminar flow condition. Simulations were conducted in the range of 500 < Re < 2000 for both water and nanofluid. volume concentrations of nanoparticle considered in the simulation are 0 %, 0.5 % ,1 % and 2%. Particles are assumed spherical in shape with a constant diameter of 40 nm. Two phase mixture model is adopted to simulate the convection flow. Mixture model which is a simplification of the Eulerian multiphase model has been chosen prior to solving the governing equations of continuity, momentum, and energy and empirical equations are applied to calculate the thermophysical properties of nanofluid. The governing equations are solved numerically using the finite-volume approach Result shows that, increasing the volume concentration and Reynolds number increases the heat transfer coefficient of working fluid, Nusselt number and thermal performance.For instance, at Re = 2000, convective heat transfer coefficient of nanofluid containing 2 % Vol. of Al2O3 was observed 156% higher than water and enhancement in thermal performance is 142%.