Numerical study on the influence of various nanofluids on the efficiency of flat-plate solar collectors (FPSC)

Abstract

Numerical investigations are conducted using finite volume method to study the laminar heat transfer in a three-dimensional flat-plate solar collector. The continuity, momentum and energy equations are discretized and the SIMPLE algorithm scheme is applied to link the pressure and velocity fields inside the domain. Three nanofluid with different types of nanoparticles, Ag (silver), MWCNT (Multiwall Carbon Nanotubes) and Al2O3 with 0.5-2 wt% volume fraction and nanoparticle diameter of 20-50 nm in base fluid (water) were selected. A constant heat flux, equivalent to solar radiation absorbed by the collector, is applied at the top surface of the absorber plate. In this research, several parameters including boundary condition (different volume flow rate, fluid inlet temperature and solar irradiance on Skudai, Malaysia), types of fluids (base fluid with different type of nanoparticles), different volume fraction, different naoparticle diameter and different solar collector tilt angle are investigated to identify their effects on the heat transfer performance of FPSC. The numerical results indicate that the three types of nanofluid enhance the thermal performance of solar collector compared to pure water and FPSC with Ag nanofluid has the best thermal performance enhancement. Heat transfer performance of FPSC improves with the increase of nanoparticle volume fraction and decrease of nanoparticle diameter. For all the cases the collector efficiency increased with the increase of volume flow rate while fluid outlet temperature decreased. The results revealed that FPSC with tilt angle of 10° and fluid inlet temperature of 28°C showed the best thermal performance.