Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : nanofluid


Theoretical Temperature Distribution Investigation in Electrical Transformer by Using Nano-Technology

Ibtisam A. Ha san; Sahar R. Fafraj; Azhar K. Azeez

Engineering and Technology Journal, 2016, Volume 34, Issue 12, Pages 2282-2295

A proposed thermal model is examined for a distribution transformer. A 2d simulation by a transient analysis in light of the Finite Element Method (FEM) was done to obtain the temperature distribution in the three phase transformer (250 KVA 11/.416 KV core type, mineral oil) using "ANSYS PROGRAM". Meanwhile, the effects of type of oil on HOST are investigated using the proposed model. To test the effect of nanoparticles on heat transfer process, the insulation oil was changed with Nanofluid; it has been used two types of Nano particles (CuO and Al2O3) with 0.5% as a volume concentration, where themaximum temperature reduced about (5%).The core material also has been changed from silicon steel to amorphous steel and caused a reduction in maximum temperature about (9.9%) in HV winding and change the interior angles from 90o to 135o, where the temperature distribution transformer is improved. The present model successfully accomplished for expecting the temperature distribution at any locations in the transformer when compared with practical measurement.

Experimental Comparison Between Conventional Coolants and (TiO2/Water) Nano fluid to select the best Coolant for Automobiles in Iraq's Summer Season

Abdulmunem R. Abdulmunem

Engineering and Technology Journal, 2016, Volume 34, Issue 5, Pages 912-926

This work, presentsnanofluids as a new coolant technology in automobile engines compared with other conventional coolants (Ethylene glycol/water(antifreeze), distilled water) experimentally.The increase in thermal conductivity of the base fluid (water) by adding nanoparticles in certain ratios led to more absorption of heat from engine block. The experimental results indicated that the drooping in exit engine coolant temperatures was about(18.5%) by using (0.3%TiO2/water)nanofluid, and about (9%) by using distilled water comparative with Ethylene glycol/water(50/50) at the test end. The increasing in radiator(heat exchanger) effectiveness was about (51%) with using nanofluid, and about (29%) with using distilled water comparative with Ethylene glycol/water(50/50) at the test end. The results indicated also that the increasing in Nusselt’s number at entrance of radiator hose was about (42.8%) with usingnanofluid and about (30.5%) with using distilled water compared with Ethylene glycol/water(50/50).This led to increase convection heat transfer coefficient at entrance of radiator hoseby about (65%) with using nanofluidand about (49.5%) with using distilled water compared with Ethylene glycol/water (50/50).

Enhanced thermal conductivity of cooling liquid using nano material's

Kheria M.Essa; Hashim Zydan Mohammed

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1179-1192

In present work alumina with grain size (50nm )and titanium dioxide with grain size (20nm ) are used tothermal conductivity is tested separately when mixed with water at different percent concentrations (0.05%, 0.1 %, 0.3%, and 0.5 W %),in order to investigate their effects on enhancement of heat transfer of pool boiling water and enhancement thermal conductivity of nanofluid.
The experimental results of thermal conductivity of water before and after adding of nanoparticles have been presented in this work. The results of a theoretical study of thermal conductivity of nanofluids with Al2O3 and TiO2 nanoparticles are also presented and compared with the experimental results. Both results showed an increment of 1.5% -1.8% enhancementshave been obtained when a small amount of nanoparticles is added to the pure water. The theoretical calculation is based on the mechanism of Brownian motion which is the reason for improvement of thermal conductivity.

Experimental Stability and Thermal Characteristics Enhancement Analysis of Water Based Boehmite Nano fluid

Atia; Mohammed Hussein J. Al; Sarah A. Abed

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1193-1210

In this work attempt was made to formulate water based boehmite (AlOOH) nanofluid in one and two steps methods. Boehmite is the first born alumina phase as prepared by sol gel route using aluminum isopropoxide precursor, exhibit a combination of excellent consistency and dispersibility in water. Plain nanofluids containing boehmite at different concentrations were investigated for colloidal, suspensions and/or dispersions stability and thermal conductivity enhancement. X-ray diffraction analysis, laser diffraction particle size analysis, viscosity, thermal conductivity measurements, TG/DSC thermal analysis and sedimentation balance were used as characterization tools. The results show promising long-term fluid stability and thermal conductivity enhancement relative to starting based fluid following non-linear dependence on particles concentration. The maximum 2.7 times enhancement in thermal conductivity occurred at narrow boehmite concentration range as a result of achieving optimum nanoparticles aggregation level where neither the case of nanoparticles homogenous dispersion nor the case of fully aggregated clusters could retain these enhancements values. This far beyond behavior from Maxwell's model was explained on the basis of the known mechanisms of thermal conductivity enhancement of nanofluids.

A Comparison Between Sinusoidal Oscilation and Constant Temperature Boundary Conditions In Annulus Filled With Porous Media Saturated With Nanofluid

Manal H. AL; Hafidh

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 831-848

A numerical study has been carried out to investigate the heat transfer by natural convection of nanofluid taking copper as nano particles and the water as based fluid in a three dimensional annulus enclosure filled with porous media between two horizontal concentric cylinders with 12 annular fins of 3mm length and 2.4 mm thickness attached to the inner cylinder under steady state condition and different wall temperature boundary conditions. The governing equations which used are continuity, momentum and energy equations under an assumptions used Darcy law and Boussinesq’s approximation which are transformed to dimensionless equations. The finite difference approach is used to obtain all the computational results using the MATLAB- 7. The parameters affected on the system are modified Rayleigh number (10 ≤Ra*≤ 500), radius ratio Rr (0.293, 0.365 and 0.435) and the volume fraction . The results show that, increasing of fin length decreases the heat transfer rate and for Ra*<100, decreasing Rr cause to decrease Nu and adding Cu nanoparticles with φ= 0.35 cause 27.9% enhancement in heat transfer. A correlation for Nu in terms of Ra, Hf and φ, has been developed for inner hot cylinder.