The stability, viscosity and thermal conductivity of carbon nanotubes nanofluids with high particle concentration: A surface modification approach

2020 ◽  
Vol 361 ◽  
pp. 957-967 ◽  
Author(s):  
Xiaoke Li ◽  
Wenjing Chen ◽  
Changjun Zou
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Surface Modification ◽  
Particle Concentration ◽  
High Particle Concentration ◽  
High Particle ◽  
The Stability

Surface Modification Approach to TiO2 Nanofluids with High Particle Concentration, Low Viscosity, and Electrochemical Activity

2015 ◽  
Vol 7 (37) ◽  
pp. 20538-20547 ◽  
Author(s):  
Sujat Sen ◽  
Vijay Govindarajan ◽  
Christopher J. Pelliccione ◽  
Jie Wang ◽  
Dean J. Miller ◽  
...  
Keyword(s):  
Surface Modification ◽  
Particle Concentration ◽  
Electrochemical Activity ◽  
High Particle Concentration ◽  
Low Viscosity ◽  
High Particle ◽  
Tio2 Nanofluids

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.

Friction and Lubrication Behavior of a Selective Laser Melted Hydraulic Spool Valve Under Contaminated Conditions

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Hongqin Ding ◽  
Peng Lu ◽  
Chao Zhang ◽  
Yi Zhu ◽  
Huayong Yang
Keyword(s):  
Particle Concentration ◽  
Sample Surface ◽  
Valve Body ◽  
Small Surface ◽  
Lubrication Regimes ◽  
High Particle Concentration ◽  
High Particle ◽  
Spool Valve ◽  
Surface Pores ◽  
Friction And Lubrication

Abstract Selective laser melting (SLM) technology has a great potential to reduce size and weight of hydraulic valves. However, the tribological performance of an SLMed valve has not been studied which is crucial for the performance and reliability of the valve, especially under contaminated conditions. In this study, the friction and lubrication behavior between an SLMed valve body and a traditional spool were studied using a scaled reciprocating test rig under various contaminated conditions (frequency at 5 Hz and 25 Hz; particle concentration at 0.4 mg/ml and 4 mg/ml; particle size at 1.6 µm and 15 µm). Three types of SLMed samples were fabricated using different exposure times: one has many large surface pores (pores area > 1000 µm2 accounts for 7.167% of the sample surface); one has a few small surface pores (pores area between 100 µm2 and 1000 µm2 accounts for 0.574% of the sample surface); and one only has micropores (pores area < 300 µm2 accounts for 0.168% of the sample surface). The density, hardness, microstructures, and pore characterization of the SLMed samples were investigated. The results indicated that the frequency greatly influenced friction and lubrication behaviors by determining lubrication regimes. The influence of surface pores on the lubrication and friction depends on contact conditions: pores which served as particle containers to reduce friction are prominent under 5 Hz frequency and high particle concentration; extra lubrication by the surface pores is observed under 25 Hz frequency and low particle concentration.

scholarly journals Thermophysical Properties of Nanofluids Composed of Ethylene Glycol and Long Multi-Walled Carbon Nanotubes

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 241
Author(s):  
Karolina Brzóska ◽  
Bertrand Jóźwiak ◽  
Adrian Golba ◽  
Marzena Dzida ◽  
Sławomir Boncel
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Ethylene Glycol ◽  
Chemical Vapor ◽  
Step Method ◽  
Mwcnt Content ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
Rotary Viscometer

In this work, thermal conductivity, viscosity, isobaric heat capacity, and density of stable carbon-based nanofluids are presented. The nanofluids under study are composed of 1,2-ethanediol (ethylene glycol, EG) and long multi-walled carbon nanotubes (MWCNTs), so-called ‘in-house 16h’ (synthesized in our laboratory via catalytic chemical vapor deposition during 16 h with a diameter of 60–80 nm and length of 770 μm). Poly(N-vinylpyrrolidone) (PVP) was used to increase the stability of nanofluids. The nanofluids were prepared via an ultrasonication-assisted, three-step method while their key thermophysical characteristics were obtained using the hot-wire technique and rotary viscometer. As a result, the addition of MWCNTs significantly improved the thermal conductivity of nanofluids by 31.5% for the highest 1.0 wt% (0.498 vol%) long MWCNT content, leaving the Newtonian character of the nanofluids practically intact.

scholarly journals Discordance between Circulating Atherogenic Cholesterol Mass and Lipoprotein Particle Concentration in Relation to Future Coronary Events in Women

2017 ◽  
Vol 63 (4) ◽  
pp. 870-879 ◽  
Author(s):  
Patrick R Lawler ◽  
Akintunde O Akinkuolie ◽  
Paul M Ridker ◽  
Allan D Sniderman ◽  
Julie E Buring ◽  
...  
Keyword(s):  
Particle Concentration ◽  
Cox Proportional Hazards ◽  
Health Study ◽  
Linear Regression Models ◽  
Apo B ◽  
Healthy Women ◽  
Lipoprotein Particle ◽  
High Particle Concentration ◽  
High Particle ◽  
Chd Risk

Abstract BACKGROUND It is uncertain whether measurement of circulating total atherogenic lipoprotein particle cholesterol mass [non–HDL cholesterol (nonHDLc)] or particle concentration [apolipoprotein B (apo B) and LDL particle concentration (LDLp)] more accurately reflects risk of incident coronary heart disease (CHD). We evaluated CHD risk among women in whom these markers where discordant. METHODS Among 27533 initially healthy women in the Women's Health Study (NCT00000479), using residuals from linear regression models, we compared risk among women with higher or lower observed particle concentration relative to nonHDLc (highest and lowest residual quartiles, respectively) to individuals with agreement between markers (middle quartiles) using Cox proportional hazards models. RESULTS Although all 3 biomarkers were correlated (r ≥ 0.77), discordance occurred in up to 20.2% of women. Women with discordant high particle concentration were more likely to have metabolic syndrome (MetS) and diabetes (both P < 0.001). Over a median follow-up of 20.4 years, 1246 CHD events occurred (514725 person-years). Women with high particle concentration relative to nonHDLc had increased CHD risk: age-adjusted hazard ratio (95% CI) = 1.77 (1.56–2.00) for apo B and 1.70 (1.50–1.92) for LDLp. After adjustment for clinical risk factors including MetS, these risks attenuated to 1.22 (1.07–1.39) for apo B and 1.13 (0.99–1.29) for LDLp. Discordant low apo B or LDLp relative to nonHDLc was not associated with lower risk. CONCLUSIONS Discordance between atherogenic particle cholesterol mass and particle concentration occurs in a sizeable proportion of apparently healthy women and should be suspected clinically among women with cardiometabolic traits. In such women, direct measurement of lipoprotein particle concentration might better inform CHD risk assessment.

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