Heat transfer of Cu–water nanofluid in an enclosure with a heat sink and discrete heat source

Abstract

Heat transfer inside horizontal and vertical enclosure filled with Cu–water nanofluid is studied. A heat sink with rectangular fins represents the base plate of the enclosure where it is heated by a discrete heat source at the bottom of the heat sink. The front face of the heat sink is kept at constant low temperature while the side walls are assumed adiabatic. The results are presented for the enclosure without and with a heat sink of one to seven fins. The ratio of enclosure height to enclosure width is 0.25 and the study is carried out at a fin length to enclosure height ratio of 0.25 and 0.5. The effect of the volume fraction and nanoparticle diameter of Cu nanoparticles is carried out for different spacings between the fins of the heat sink and different Rayleigh numbers. The numerical model is solved by a finite volume method. The results show that the average Nusselt number on the heat source increases with increase Rayleigh number and volume fraction of Cu nanoparticles and with decreasing diameter of Cu nanoparticles. At low Ra number (Ra=103), the average Nusselt number increases with increasing number of fins and increasing L/H. At high Raleigh number (Ra=106), an increase in the value of L/H has no great effect on the average Nusselt number. At high Rayleigh number (Ra=106) and low nanoparticle diameter and high volume fraction, the enclosure with a heat sink of one fin and L/H of 0.5 has the maximum average Nusselt number for horizontal and vertical enclosure.