Performance Investigation of TiO2 Nanofluid Coolant for Automobile Cooling Applications

2015 ◽  
Vol 645-646 ◽  
pp. 444-448 ◽  
Author(s):  
Jin Mao Chen ◽  
Xiao Ying Sun ◽  
Guan Jun Leng ◽  
Jing Heng Feng
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Transfer Enhancement ◽  
Automobile Engine ◽  
Conductivity Enhancement ◽  
Engine Cooling ◽  
Engine Coolant

This study focused on the evaluation of TiO2 nanofluid coolant for automobile engine cooling applications. It was observed that, about 3% of thermal conductivity enhancement and above 10% convective heat transfer enhancement could be achieved with the usage of 1.0 wt.% TiO2 nanofluid coolant compared to base coolant without nanoparticles. More importantly, corrosion-inhibiting properties of TiO2 nanofluid coolant were investigated, which indicated that the nanofluid coolant possess the characteristics of a qualified engine coolant should have. The evaluation results showed that the nanofluid coolant could be a promising engine coolant for automobiles.

Indirect Involvement of Amorphous Carbon Layer on Convective Heat Transfer Enhancement Using Carbon Nanofibers

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
T. J. Taha ◽  
L. Lefferts ◽  
T. H. van der Meer
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Surface Area ◽  
Carbon Nanofibers ◽  
Convective Heat ◽  
Amorphous Carbon ◽  
Nickel Wire ◽  
Transfer Enhancement

In this work, an experimental heat transfer investigation was carried out to investigate the combined influence of both amorphous carbon (a-C) layer thickness and carbon nanofibers (CNFs) on the convective heat transfer behavior. Synthesis of these carbon nanostructures was achieved using catalytic chemical vapor deposition process on a 50 μm nickel wire at 650 °C. Due to their extremely high thermal conductivity, CNFs are used to augment/modify heat transfer surface. However, the inevitable layer of a-C that occurs during the synthesis of the CNFs layer exhibits low thermal conductivity which may result in insulating the surface. In contrast, the amorphous layer helps in supporting and mechanically stabilizing the CNFs layer attachment to the polycrystalline nickel (Ni270) substrate material. To better understand the influences of these two layers on heat transfer, the growth mechanism of the CNFs layer and the layer of carbon is investigated and growth model is proposed. The combined impact of both a-C and CNFs layers on heat transfer performance is studied on three different samples which were synthesized by varying the deposition period (16 min, 23 min, and 30 min). The microwire samples covered with CNF layers were subjected to a uniform flow from a nozzle. Heat transfer measurement was achieved by a controlled heat dissipation through the microwire to attain a constant temperature during the flow. This measurement technique is adopted from hot wire anemometry calibration method. Maximum heat transfer enhancement of 18% was achieved. This enhancement is mainly attributed to the surface roughness and surface area increase of the samples with moderate CNFs surface area coverage on the sample.

Characterization and Convective Heat Transfer With Nanofluids

2011 ◽  
Author(s):  
Yijun Yang ◽  
Alparslan Oztekin ◽  
Sudhakar Neti ◽  
Satish Mohapatra
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Al2o3 Nanoparticles ◽  
Pumping Power ◽  
Transfer Enhancement ◽  
Low Concentrations

Heat transfer and flow dynamics of nanofluids are investigated in developing laminar pipe flows. Characterization of nanofluids is examined by measuring resultant effective particle size, thermal conductivity and viscosity for various values of particle concentrations and temperatures. Nanofluids considered in this study are diamond-graphene (ND-50) nanoparticle in silicone oil (Syltherm 800), and Al2O3 nanoparticles in DI water with and without dispersers/stabilizers. The particle size of various nanofluids is determined quantitatively from measurements using Dynamic Light Scattering device (DLS) and also determined qualitatively from SEM images. Thermal conductivity measurements are conducted by using nano-flash LFA447 device for particle volume fractions ranging from 0.8% to 5.1%. Measured values of thermal conductivity of all fluids at low concentrations agree well with the results predicted by Maxwell model. Viscosity measurements are conducted using parallel plate geometry Rheometrics viscometer at different concentration and temperature as a function of shear rate. At low shear rates the fluid behaves as a Newtonian fluid while it becomes a shear thinning fluid at higher particle concentration of the same nanofluid. There is a significant increase in the viscosity at even low concentrations. Viscosity of nanofluids is also a strong function of temperature at all values of concentration considered in this study. The significant increase in viscosity may diminish nanofluids’ application as an advanced heat transfer fluid. The effects of nanofluid on the drag reduction and heat transfer enhancement are determined and compared with the pressure drop and heat transfer coefficient measurements with the base fluids at the same flow conditions. Our experimental measurements indicate that the pumping power to flow nanofluids is nearly the same as the pumping power required to flow the same amount of base fluid although the viscosity of nanofluids are significantly higher. Convective heat transfer enhancement with the nanofluids is limited to 5% or slightly higher as has also been reported by other workers. Hence addition of nanoparticles into heat transfer fluids could have the potential for heat transfer enhancement in pipe flow without paying the penalty of increasing pumping power.

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