2 results listed
This study investigates the heat transfer
enhancements of CuO nanofluid according to nanoparticle size.
For maximum heat transfer enhancement, optimum nanoparticle
diameter is going to be found. In this numerical study, forced
convection nanofluid flow in a 0.01-m x 0.01-m cross-sectioned
and 3-m long square duct under turbulent flow regime was
investigated. Constant heat flux of 20 kW/m2 was applied to the
surfaces of the duct. CuO/water nanofluid was used in analyses
to enhance the convective heat transfer of the base fluid.
Thermo-physical properties of nanofluid are constant. Analyses
were performed for Reynolds numbers between 104 and 105, also
for volume concentrations between 0% and 4%. The finite
volume discretization method was used to solve the governing
equations. Single phase model was considered. Thermophysical
properties of the nanofluid were found thanks to the single phase
correlations which depended on nanoparticle diameter. The
effects of nanoparticle diameter on velocity distribution, average
Nusselt number, and average Darcy friction factor were
investigated in detail. The results indicate that higher volume
concentrations of CuO/water nanofluid offers more average
convective heat transfer enhancement. Higher nanoparticle size
nanofluids offer lower enhancement
1.st International Conference Energy Systems Engineering
ıcese'17
Mutlu TEKİR
Recep EKİCİLER
Kamil ARSLAN
In this study the effect of nanofluids on collector
performance was numerically investigated when using as
working fluids in solar collectors which are commonly used in
solar energy applications. Nanofluids are produced by adding
nanoparticles to a base fluid as known. Thermophysical
properties of base fluids change. The most important property of
nanofluids is thermal conductivity enhancement. In this study
ethylene glycol – water mixture was used as a base fluid which is
especially used as cold climates for reducing freezing point. The
reasons for this are expanding the range of working temperature
and preventing the flow from higher density and viscosity of
ethylene glycol at the same time. TiO2/EG-Pure Water
nanofluids were used as working fluids in an evacuated U-tube
solar collector at 1.0 – 4.0% volumetric concentrations with 30-
70% EG-PW base fluid for determining the effect of nanofluids
on collector thermal efficiency. An evacuated tube solar collector
with copper U-tube was modeled in FLUENT 17.0 and thermal
efficiency of it was calculated by solving of flow field of the
collector. 18.1% enhancement was obtained as maximum in
thermal efficiency when using nanofluid as a working fluid. It
was determined that the flow rate of the fluid was a significant
parameter on thermal efficiency of the solar collector. The
highest collector efficiency was obtained at 4.0% nanoparticle
volume concentration and ṁ=0.045 kg/s.
1.st International Conference Energy Systems Engineering
ıcese'17
Hüseyin Kaya
Kamil ARSLAN