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Abstract

ABSTRACT
In this investigation the thermal properties of nanofluids and three types of nanoparticles which are ((Cu 25 nm)+ E G), (Al(30nm)) + E G) and (Zr2O3 (50nm) + EG) was studied using two types of base fluids (ethylene glycol and distilled water). Ethylene Glycol was proven to be better than distilled water – based fluid in the nanofluids for having two properties which are thermal conductivity and specific heat, while distilled water was better than ethylene glycol for having two properties which are density and viscosity. The rates of increase in thermal conductivity in this research are 45%, 22 % and 7.25 % to each of the Cu/ DW, Al / DW and Zr2O3 / DW respectively, while these percentages are 30 %, 17 %, 4.5 % and to all of the Cu / EG, Al/EG and Zr2O3 / EG respectively at 2.5% vol a concentration and that the cause of this increase for Cu / EG is that the small size of the particles Cu (25nm), while the viscosity of Zr2O3 / EG is larger than Cu / EG and Al/ EG due to the large size of the particles Zr2O3 (50nm). The specific heat capacity of nanofluid made by ethylene glycol and Cu (25nm), Al (30nm) and Zr2O3 (50nm) nanoparticle inclusions measured at room temperature were compared with two kinds of models for determination of the specific heat capacity of nanofluid. The result indicates that the specific heat capacity of Cu (25nm), Al (30nm), Zr2O3 (50nm) nanofluid decreases gradually with increasing volume concentration of nanoparticles. It can be found that there is almost linear relation between shear stress and shear rate for all concentrations of nanofluids which confirm a Newtonian behavior for Cu / EG, Al/EG and Zr2O3/ EG in volume fraction 0.25 and 2.5 % vol as well as Cu / DW, Al/ DW and Zr2O3/ DW.

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