Effect of pH and Chemical Surfactant on Thermal Conductivity Enhancement of Cu-H2O Nanofluids

2008 ◽  
Author(s):  
Xinfang Li ◽  
Dongsheng Zhu ◽  
Xianju Wang ◽  
Nan Wang ◽  
Zhengdong Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Ph Value ◽  
Combined Treatment ◽  
Weight Fraction ◽  
Effect Of Ph ◽  
Conductivity Enhancement ◽  
Practical Applications ◽  
Heat Transfer Fluids ◽  
Ph Values ◽  
Thermal Constants

Nanofluids have been attractive for the last few years with the enormous potential to improve the efficiency of heat transfer fluids. This work focuses on the effect of pH and sodium dodecylbenzenesulfonate (SDBS) surfactant on the thermal conductivity of nanofluids.The thermal conductivity was measured by a Hot Disk Thermal Constants Anlyser. The results showed that the thermal conductivity enhancements of Cu–H2O nanofluids are highly dependent on the weight fraction of nanoparticle, pH values and SDBS surfactant concentration of nano-suspensions. The Cu–H2O nanofluids with an ounce of Cu have noticeably higher thermal conductivity than the base fluid without nanoparticles, For Cu nanoparticles at a weight fraction of 0.001 (0.1 wt %), thermal conductivity was enhanced by up to 10.7%, with an optimal pH value and SDBS concentration for the highest thermal conductivity. Therefore, the combined treatment with both the pH and chemical surfactant is recommended to improve the thermal conductivity for practical applications of nanofluid.

Experimental Investigation on the Influence of Graphene Nanoplatelets Dispersion on the Thermal Conductivity of Sunflower Oil

2019 ◽  
Vol 19 (02) ◽  
pp. 1950011
Author(s):  
M. Muthuraj ◽  
J. Bensam Raj ◽  
J. Sunil
Keyword(s):  
Thermal Conductivity ◽  
Sunflower Oil ◽  
Weight Fraction ◽  
Graphene Nanoplatelets ◽  
Key Factors ◽  
Temperature Dependent ◽  
Conductivity Enhancement ◽  
Energy Demands ◽  
Minimum Margin ◽  
Artificial Neural Network Ann

In the past decades, considerable efforts have been made for the development of energy-efficient and eco-friendly convective heat transfer and lubricating agents because of growing energy demands, precision manufacturing, miniaturization and sustainability issues. In this study, different concentrations of graphene–sunflower oil nanofluid were prepared and their thermal conductivity was experimentally investigated and compared with the correlations of similar researches found in the literature. The morphology of graphene nanoplatelets was appraised by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results show that the thermal conductivity of nanofluid was enhanced with temperature and nanoparticles weight fraction. The nanoconvection at high temperatures, less meandering mobility of graphene nanoplatelets and high kinematic viscosity of graphene nanofluids at low temperatures were identified as the key factors for the thermal conductivity enhancement. Further, the concentration and temperature-dependent theoretical correlation were proposed for estimating the thermal conductivity of graphene nanofluids using backpropagation algorithm of artificial neural network (ANN) with the minimum margin of deviation.

Analysis of nanofluids as a means of thermal conductivity enhancement in heavy machineries

2014 ◽  
Vol 66 (2) ◽  
pp. 238-243 ◽  
Author(s):  
Ayush Jain ◽  
Imbesat Hassan Rizvi ◽  
Subrata Kumar Ghosh ◽  
P.S. Mukherjee
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Ethylene Glycol ◽  
Base Fluid ◽  
High Concentration ◽  
Content Type ◽  
Conductivity Enhancement ◽  
Heavy Machinery ◽  
Heat Transfer Fluids ◽  
Experimental Findings

Purpose – Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues. Design/methodology/approach – Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al2O3 in base fluid water, Al2O3 in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO2 in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al2O3 in base fluid SAE 30 particularly for heavy machinery applications. Findings – The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations. Research limitations/implications – It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values. Originality/value – Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

scholarly journals Effect of the Acidic and Alkaline Solutions on K2CrO4 and K2Cr2O7 by Ultraviolet and Visible Measurement

2019 ◽  
Vol 30 (1) ◽  
pp. 221
Author(s):  
Mohammad Radi Mohammad ◽  
Hasanain Saad Azeez
Keyword(s):  
Ph Value ◽  
Red Shift ◽  
Alkaline Solutions ◽  
Visible Spectroscopy ◽  
Solution Ph ◽  
Effect Of Ph ◽  
Ph Values ◽  
Uv Visible

In this work different amount of acidic (HCl) and alkaline (NaOH) solutions were added to stoke solutions of K2CrO4 and K2Cr2O7 to show the effect of pH values on their spectra. The results of UV-Visible spectroscopy shows that, the Changing of solution pH value when drops of HCl were added led to shift wavelength of K2CrO4 spectrum while no change has been occurred in K2Cr2O7 spectrum. However, Changing PH values solution by adding drops of NaOH led to change in wavelength red shift for K2Cr2O7 while no changes has been occurred in spectrum of K2CrO4.

Effect of pH Values on Conversion of Calcite Crystals into Calcium Phosphate Phases in Buffer Solutions

2007 ◽  
Vol 353-358 ◽  
pp. 2183-2186 ◽  
Author(s):  
Ya Ping Guo ◽  
Bao Qiang Li ◽  
Yu Zhou ◽  
De Chang Jia
Keyword(s):  
Calcium Phosphate ◽  
Ph Value ◽  
Octacalcium Phosphate ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Buffer Solution ◽  
Effect Of Ph ◽  
X Ray ◽  
Buffer Solutions ◽  
Ph Values

Calcium phosphate phases with laminar-plate structure were converted from calcite powders after soaking in phosphate buffer solutions of pH’s 6.0-8.0 at 37 °C for 9 days. The effect of pH values on the conversion of calcite crystals was investigated by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. If the pH value of a buffer solution is kept at 6.0, calcite powders are converted mainly to dicalcium phosphate dehydrate (DCPD) or octacalcium phosphate (OCP). If the pH value is kept at 6.4 or 7.0, calcite powders are converted mainly to OCP. Hydroxyapatite (HAP) with poorly crystalline can be obtained from calcite powders both by treatment of a basic buffer solution, and by treatment of an acid buffer solution without regulating its pH value during the reaction. The conversion mechanism of calcite crystals is a dissolution-precipitation reaction.

scholarly journals A Novel Experimental Study on the Rheological Properties and Thermal Conductivity of Halloysite Nanofluids

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1834
Author(s):  
Thong Le Ba ◽  
Ahmed Qani Alkurdi ◽  
István Endre Lukács ◽  
János Molnár ◽  
Somchai Wongwises ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Halloysite Nanotubes ◽  
Visual Observation ◽  
X Ray ◽  
Conductivity Enhancement ◽  
Practical Applications ◽  
Zeta Potentials ◽  
Ft Ir ◽  
The Stability ◽  
Ft Ir Spectroscopy

Nanofluids obtained from halloysite and de-ionized water (DI) were prepared by using surfactants and changing pH for heat-transfer applications. The halloysite nanotubes (HNTs) nanofluids were studied for several volume fractions (0.5, 1.0, and 1.5 vol%) and temperatures (20, 30, 40, 50, and 60 °C). The properties of HNTs were studied with a scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), Fourier-transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), Raman spectroscopy and thermogravimetry/differential thermal analysis (TG/DTA). The stability of the nanofluids was proven by zeta potentials measurements and visual observation. With surfactants, the HNT nanofluids had the highest thermal conductivity increment of 18.30% for 1.5 vol% concentration in comparison with the base fluid. The thermal conductivity enhancement of nanofluids containing surfactant was slightly higher than nanofluids with pH = 12. The prepared nanofluids were Newtonian. The viscosity enhancements of the nanofluid were 11% and 12.8% at 30 °C for 0.5% volume concentration with surfactants and at pH = 12, respectively. Empirical correlations of viscosity and thermal conductivity for these nanofluids were proposed for practical applications.

Electrokinetic Properties and Their Effect on Thermal Conductivity of Nanofluids

2008 ◽  
Author(s):  
S. M. Sohel Murshed ◽  
Kai Choong Leong ◽  
Chun Yang
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Effective Thermal Conductivity ◽  
Electrolyte Concentration ◽  
Ph Value ◽  
Deionized Water ◽  
Ph Values ◽  
Nacl Concentration ◽  
Effects Of Ph ◽  
Similar Decrease

This paper presents the effects of pH value, surfactant, and electrolyte concentration on zeta potential and effective thermal conductivity of nanofluids. The zeta potential of TiO2 (15 nm) nanoparticles in deionized water of different pH values was measured and the iso-electrical point was found to be between 4.9 and 5.2. The results show that the higher the electrolyte concentration, the smaller the particle zeta potential, which results in increased agglomeration of particles. The enhanced thermal conductivity of TiO2/deionized water-based nanofluids was found to decrease with increasing pH value or electrolyte concentration. For example, for 0.2 volume %, the thermal conductivity of this nanofluid was found to decrease from 5.5% to 2.5% when the pH value was increased from 3.4 to 9. A similar decrease (≈ 2%) in thermal conductivity was observed when NaCl concentration was increased from 0.01 mM to 10 mM. The presence of a surfactant showed considerably larger enhancement of the effective thermal conductivity compared to that of nanofluids without surfactant.

Effect of pH in Systems on Crystallinity and Morphology of Synthesized Xonotlite Whiskers

2011 ◽  
Vol 382 ◽  
pp. 384-387 ◽  
Author(s):  
Fei Liu ◽  
Xiao Dan Wang ◽  
Jian Xin Cao
Keyword(s):  
Ph Value ◽  
Effect Of Ph ◽  
Synthesis Conditions ◽  
Ph Values

The different pH values in CaO-SiO2-H2O systems were taken into account to prepare xonotlite whiskers without any surfactant, special instruments and synthesis conditions. Effect of pH values in system on the crystallinity and morphology of synthesized xonotlite whiskers was studied by using XRD and SEM techniques. The results indicated that the different pH values in system had little effect on the crystallinity of synthesized xonotlite, but posed significant impact on the morphology of xonotlite whiskers. The higher pH value is, the lager scale xonotlite whiskers appear. Little whiskers were synthesized in the system of pH 11.5, but in the system of pH 13.0, the formation of xonotlite whiskers was promoted and xonotlite whiskers with 20-40 μm in length and 400 nm in diameter were prepared at 225 °C for 15 h.

Influencing Factors for Thermal Conductivity Enhancement of Nanofluids

2009 ◽  
Author(s):  
Huaqing Xie ◽  
Wei Yu ◽  
Yang Li ◽  
Lifei Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Influencing Factors ◽  
Silicone Oil ◽  
Thermal Conductivity Enhancement ◽  
Zno Nps ◽  
Conductivity Enhancement ◽  
Heat Transfer Fluids ◽  
Different Shapes ◽  
Al2o3 Nps

Nanofluids have attracted increasing interest for more than a decade. A number of studies have demonstrated that nanofluids presented intriguing heat transfer enhancement performances. We produced a series of nanofluids and measured their thermal conductivities. The most used heat transfer fluids including deionized water (DW), ethylene glycol (EG), glycerol, silicone oil, and the binary mixture of DW and EG were used as the base fluids. Various nanoparticles (NPs) including Al2O3 NPs with different sizes, SiC NPs with different shapes, MgO NPs, ZnO NPs, SiO2 NPs, Fe3O4 NPs, TiO2 NPs, diamond NPs (DNPs), and carbon nanotubes (CNTs) with different pretreatments have been used as additives. In the present paper, we summarized our experimental results to elucidate the influencing factors for thermal conductivity enhancement of nanofluids. The thermal transport mechanisms in nanofluids were further discussed and the promising approaches for optimizing the thermal conductivity of nanofluids were proposed.

Effect of pH Value on the Electrodeposition Potential of Cu-In Alloy Film

2008 ◽  
Vol 373-374 ◽  
pp. 216-219
Author(s):  
H.X. Yang ◽  
Zhen Lun Song ◽  
Yong Wei Song ◽  
Hui Zhang
Keyword(s):  
Ph Value ◽  
Alloy Film ◽  
Deposition Potential ◽  
Electrochemical Measurements ◽  
Precursor Film ◽  
Effect Of Ph ◽  
Electro Deposition ◽  
Ph Values ◽  
The Relationship

Electro-deposition Cu-In alloy can act as the precursor film to prepare CuInSe2 compound by selenating treatment. The effect of pH value on the electrodeposition potential of Cu-In alloy was investigated by electrochemical measurements in this paper. The relationship between the pH values and deposition potential was analyzed. Then uniform Cu-In alloy film was successfully prepared based on the special potential and pH.

Enhancing the Stability of Asphalt Emulsion Using Environmentally Friendly Cationically Modified Hydroxyethyl Cellulose (CMHEC) at Different Concentrations and pH Values

2021 ◽  
Vol 58 (4) ◽  
pp. 303-310
Author(s):  
Xiaoxi Wang ◽  
Runhan Hou ◽  
Qian Zhang ◽  
Osama M. Darwesh ◽  
Mengyao Gao ◽  
...  
Keyword(s):  
Phase Separation ◽  
Apparent Viscosity ◽  
Ph Value ◽  
Ph Effect ◽  
Environmentally Friendly ◽  
Hydroxyethyl Cellulose ◽  
Asphalt Emulsion ◽  
Effect Of Ph ◽  
Ph Values ◽  
The Stability

Abstract The cationically modified hydroxyethyl cellulose (CMHEC) was synthesized successfully and applied for preparing the cationic asphalt emulsion. The apparent viscosity and phase separation of the emulsion were studied at different CMHEC concentrations and pH values. The results indicated that the apparent viscosity of the emulsion was increased with increasing CMHEC concentration, and the phase separation was significantly reduced correspondingly. In addition, the effect of pH value on the emulsion quality was involved. The apparent viscosity of the emulsion showed the tendency to decrease firstly and then increase to the minimum value at pH 2. All results indicated that CMHEC has excellent potential in the manufacture of asphalt emulsion and the research of the pH effect on the formulation of asphalt emulsion has essential significance.

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