scholarly journals Evaporation Rate of Colloidal Droplets of Jet Fuel and Carbon-Based Nanoparticles: Effect of Thermal Conductivity

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1297 ◽  
Author(s):  
Ahmed Aboalhamayie ◽  
Luigi Festa ◽  
Mohsen Ghamari
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanoparticles ◽  
Evaporation Rate ◽  
Radiation Heat Transfer ◽  
Colloidal Suspensions ◽  
Force Convection ◽  
Jet Fuel ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Thermo Physical Properties

Adding nanoparticles to liquid fuel is known to promote its combustion characteristics through improving several thermo-physical properties. This study investigates the effects of adding carbon nanoparticles on thermal conductivity and evaporation rate of liquid jet fuel. Multi-walled carbon nanotubes, activated carbon nanoparticles, and graphene nanoplatelets were added to jet fuel at different concentrations to prepare colloidal suspensions. Thermal conductivity is determined by passing known amounts of heat through a very thin layer of fuel and measuring temperature difference across its thickness. A fiber-supported droplet technique is also used to evaluate evaporation rate due to force convection of a hot inert gas. It is observed that both thermal conductivity and evaporation rate increase as a result of nanoparticle addition. Since there is no radiation heat transfer mechanism, the increase in evaporation rate is concluded to be only due to enhanced thermal conductivity.

Thermal Conductivity of Colloidal Suspensions of Jet Fuel and Carbon-Based Nanoparticles and its Effect on Evaporation Rate

2018 ◽  
Author(s):  
Mohsen Ghamari ◽  
Ahmed Aboalhamayie
Keyword(s):  
Thermal Conductivity ◽  
Burning Rate ◽  
Evaporation Rate ◽  
Colloidal Suspensions ◽  
Jet Fuel ◽  
Liquid Fuels ◽  
Multi Walled Carbon Nanotubes ◽  
Carbon Based Nanomaterials ◽  
Walled Carbon Nanotubes ◽  
Carbon Based

Recent studies have shown that addition of nano-sized particles to liquid fuels could significantly enhance major combustion characteristics such as burning rate and ignition delay. Colloidal suspensions are known to have enhanced optical properties and thermal conductivity compared to neat liquids; however, in the case of colloidal fuels, the main mechanism responsible for such enhanced properties is not well understood. To better understand these phenomena, colloidal suspensions of jet fuel and different types of carbon-based nanomaterials (carbon nanoparticles, multi-walled carbon nanotubes, and graphene nanoplatelets) prepared at different particle loadings were experimentally tested for their thermal conductivities. Colloidal suspensions of nanotubes showed higher conductivity compared to that of graphene and nanoparticle. This could justify higher burning rate of these fuels. Furthermore, and to differentiate between the effects of thermal conduction and radiation, droplet evaporations tests were carried out on colloidal suspensions of carbon nanoparticle under forced convection and in the absence of any radiation source. It was found that the presence of nanoparticle in jet fuel initially increases evaporation rate. However, a reduction in evaporation rate was observed at higher concentration as a result of particles agglomeration.

scholarly journals Stability and Thermo-Physical Properties of Ethylene Glycol Based Nanofluids for Solar Thermal Applications

2021 ◽  
Vol 39 (1) ◽  
pp. 137-144
Author(s):  
Raviteja Surakasi ◽  
Jaikumar Sagari ◽  
Krishna Bharath Vinjamuri ◽  
Bhanuteja Sanduru ◽  
Srinivas Vadapalli
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Ethylene Glycol ◽  
Physical Properties ◽  
Dynamic Viscosity ◽  
Temperature Range ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Thermo Physical Properties ◽  
Surfactant Assisted

This article summarizes research involving the evaluation of the thermo-physical properties of ethylene- glycol-based solar thermic fluids oxidized multi-walled carbon nanotubes. Nanofluids were prepared with Ethylene glycol and water as base fluids in 100:0, 90:10 and 80:20 ratios. Base fluids of three categories were dispersed with surfactant-assisted multi-walled carbon nanotubes (MWCNTs) and oxidized MWCNTs in the weight fractions of 0.125, 0.25, and 0.5 percentages to check the influence of surface modification technique on the thermophysical properties. The variation in zeta potential is studied to examine the dispersion stability during 2 months. Thermal conductivity and dynamic viscosity were measured by hot disk method and Anton paar viscometer, respectively. Significant enhancement of thermal conductivity by 15 to 24 % was observed when the base fluids are dispersed with oxidized MWCNTs. In the case of nanofluids dispersed with surfactant-assisted MWCNTs, the improvement is significantly less compared to oxidized MWCNTs. Nanofluids' dynamic viscosity is found to be higher compared to base fluids in the temperature range of 50 to 70 oC. A comprehensive mathematical equation suitable for all weight fraction of MWCNTs and volume percentages of Ethylene glycol was developed, which can forecast the temperature range. The correlation could fit well with the experimental data in reasonable limits.

scholarly journals Carbon Nanofibers from Carbon Nanotubes by 1.2 keVAr+Sputtering at Room Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Shuang-Xi Xue ◽  
Qin-Tao Li ◽  
Xian-Rui Zhao ◽  
Qin-Yi Shi ◽  
Zhi-Gang Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Carbon Nanofibers ◽  
Carbon Nanoparticles ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Carbon Nanowires

Multi-walled carbon nanotubes (MWCNTs) were irradiated by 1.2 keV Ar ion beams for 15–60 min at room temperature with current density of 60 µA/cm2. The morphology and microstructure are investigated by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that carbon nanofibers are achieved after 60 min ion irradiation and the formation of carbon nanofibers proceeds through four periods, carbon nanotubes—amorphous carbon nanowires—carbon nanoparticles along the tube axis—conical protrusions on the nanoparticles surface—carbon nanofibers from the conical protrusions.

Thermal Conductivity Measurement for Carbon-Nanotube Suspensions with 3ω Method

2009 ◽  
Vol 60-61 ◽  
pp. 394-398 ◽  
Author(s):  
Gen Sheng Wu ◽  
Jue Kuan Yang ◽  
Shu Lin Ge ◽  
Yu Juan Wang ◽  
Min Hua Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Aqueous Suspension ◽  
Conductivity Measurement ◽  
3Ω Method ◽  
Conductivity Enhancement ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.

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