Stability of Nanofluids for Heat Pipe

2014 ◽  
Vol 789 ◽  
pp. 6-11 ◽  
Author(s):  
Jian Liu ◽  
Sheng Lu ◽  
Qi Chen ◽  
Jun Hao Zhang ◽  
Shou Guang Yao
Keyword(s):  
Heat Pipe ◽  
Base Fluid ◽  
Deionized Water ◽  
Suspension Stability ◽  
Step Method ◽  
Sedimentation Method ◽  
Better Than ◽  
Mass Concentrations

Different mass concentrations of Al2O3, SiO2, CuO nanofluids were made by using two-step method with the three types of base fluids deionized water, ethanol and ethylene glyco. The suspension stability of nanofluids and its effect by adding anion and cation surfactants through sedimentation method were studied. The results show that ehylene glycol is as the base fluid, the suspension stability of nanofluids with DW as the base fluid is worst. The suspension stability of Al2O3, SiO2, CuO nanofluids is significantly improved by addition of appropriate dosage of adding anion and cation surfactants for different base fluids. The effect of HTAB is better than that of SDBS.

Investigation of the effects of base fluid type of the nanofluid on heat pipe performance

2020 ◽  
pp. 095765092091628 ◽  
Author(s):  
Duygu Yilmaz Aydin ◽  
Metin Gürü ◽  
Adnan Sözen ◽  
Erdem Çiftçi
Keyword(s):  
Ethylene Glycol ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Base Fluid ◽  
Sodium Dodecyl ◽  
Active Agent ◽  
Deionized Water ◽  
Working Fluid ◽  
Fluid Type ◽  
Surface Active

Most recently, an ascending tendency in nanoparticles containing working fluid utilization has been observed in such thermal systems as double pipe heat exchangers and thermosiphons in so far as its advantages upon the performance of such systems. In order to investigate how the type of the base fluid affects the nanofluid’s properties used for thermal applications, an experimental test rig was setup and two different nanofluid each of which involves different base fluid, but same nanoparticles and surface active agent were tested. During the nanofluid preparation process, bauxite nanoparticles as nanoparticle material and sodium dodecyl benzene sulfonate as surface active agents were used in volume fractions of 2% and 0.5%, respectively. As the base fluid type, ethylene glycol and deionized water were utilized. The tests were conducted under diverse working conditions and vacuum pressure. Distribution of temperature ahead the heat pipe wall, efficiency and heat pipe’s thermal resistance was experimentally investigated. It was observed from the experiments that each nanofluid improved the heat pipe performance significantly; however, deionized water/bauxite nanofluid gave the best results in terms of heat pipe’s thermal performance. For each nanofluid, the maximum increment in efficiency was observed under 200 W heating power and 10 g/s cooling water mass flow rate conditions, and improvement rates were 29.5% and 13.3% for ethylene glycol-based and deionized water-based nanofluids, respectively. At least 20% of decline in thermal resistance of the heat pipe was also recorded, when nanofluid was employed as working fluid.

scholarly journals Synthesis of hybrid nanofluid with two-step method

2018 ◽  
Vol 67 ◽  
pp. 03057 ◽  
Author(s):  
Wayan Nata Septiadi ◽  
Ida Ayu Nyoman Titin Trisnadewi ◽  
Nandy Putra ◽  
Iwan Setyawan
Keyword(s):  
Thermal Conductivity ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Fluid ◽  
Hybrid Nanofluid ◽  
Test Results ◽  
Step Method ◽  
Fluid Mixture ◽  
High Level ◽  
Better Than

Nanofluid is a liquid fluid mixture with a nanometer-sized solid particle potentially applied as a heat transfer fluid because it is capable of producing a thermal conductivity better than a base fluid. However, nanofluids have a weakness that is a high level of agglomeration as the resulting conductivity increases. Therefore, in this study, the synthesis of two nanoparticles into the base fluid called hybrid nanofluids. This study aims to determine the effect of nanoparticle composition on the highest thermal conductivity value with the lowest agglomeration value. This research was conducted by dispersing Al2O3-TiO2 nanoparticles in water with volume fraction of 0.1%, 0.3%, 0.5%, 0.7% in the composition of Al2O3-TiO2 ratio of 75%:25%, 50%:50%, 25%:75%. The synthesis was performed with a magnetic stirrer for 30 minutes. The tests were carried out in three types: thermal conductivity testing with KD2, visual agglomeration observation and absorbance measurements using UV-Vis, wettability testing with HSVC tools and Image applications. The test results showed that the ratio composition ratio of 75% Al2O3-25% TiO2 with a volume fraction of 0.7% resulted in an increase in optimum thermal conductivity with the best wettability and the longest agglomeration level.

Application of Dispersibility Mechanism for the Dispersibility of ZrB2 Powder Materials in the Liquor

2013 ◽  
Vol 432 ◽  
pp. 51-55
Author(s):  
Jie Guang Song ◽  
Xiu Qin Wang ◽  
Ming Han Xu ◽  
Shi Bin Li ◽  
Gang Chang Ji
Keyword(s):  
High Performance ◽  
Deionized Water ◽  
Powder Materials ◽  
New Materials ◽  
Polymethacrylic Acid ◽  
Key Technology ◽  
Sedimentation Method ◽  
Fast Development ◽  
Better Than

With the fast development of preparing technology of new materials, the solving method of conglobation and decentralization problem of superfine powders already is key technology for preparing and developing new high-performance materials. Through investigating the dispersibility mechanism of particles in the liquor, the dispersibility mechanism is applied for the dispersibility of ZrB2 particles with the sedimentation method. When pH is 9, the dispersibility of ZrB2 particles is the best than that of other pH, the dispersibility of ZrB2 particles using dispersant in the ZrB2 suspension is better than that of using pure deionized water, the dispersibility of ZrB2 particles adding polymethacrylic acid ammonium in the ZrB2 suspension is the best than other conditions.

Experimental and theoretical investigation of heat transfer characteristics of cylindrical heat pipe using Al2O3–SiO2/W-EG hybrid nanofluids by RSM modeling approach

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
R. Vidhya ◽  
T. Balakrishnan ◽  
B. Suresh Kumar
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Diffraction Spectrum ◽  
Step Method ◽  
Ceramic Nanoparticles ◽  
Transfer Mechanisms

AbstractNanofluids are emerging two-phase thermal fluids that play a vital part in heat exchangers owing to its heat transfer features. Ceramic nanoparticles aluminium oxide (Al2O3) and silicon dioxide (SiO2) were produced by the sol-gel technique. Characterizations have been done through powder X-ray diffraction spectrum and scanning electron microscopy analysis. Subsequently, few volume concentrations (0.0125–0.1%) of hybrid Al2O3–SiO2 nanofluids were formulated via dispersing both ceramic nanoparticles considered at 50:50 ratio into base fluid combination of 60% distilled water (W) with 40% ethylene glycol (EG) using an ultrasonic-assisted two-step method. Thermal resistance besides heat transfer coefficient have been examined with cylindrical mesh heat pipe reveals that the rise of power input decreases the thermal resistance and inversely increases heat transfer coefficient about 5.54% and 43.16% respectively. Response surface methodology (RSM) has been employed for the investigation of heat pipe experimental data. The significant factors on the various convective heat transfer mechanisms have been identified using the analysis of variance (ANOVA) tool. Finally, the empirical models were developed to forecast the heat transfer mechanisms by regression analysis and validated with experimental data which exposed the models have the best agreement with experimental results.

Comparative Study of Cooling Performance of Automobile Radiator Using Al2O3-Water and Carbon Nanotube-Water Nanofluid

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Sandesh S. Chougule ◽  
S. K. Sahu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Base Fluid ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Transfer Performance ◽  
Nanoparticle Concentration ◽  
Cooling Performance ◽  
Forced Convective Heat Transfer ◽  
Better Than

In the present study, the forced convective heat transfer performance of two different nanofluids, namely, Al2O3-water and CNT-water has been studied experimentally in an automobile radiator. Four different concentrations of nanofluid in the range of 0.15–1 vol. % were prepared by the additions nanoparticles into the water as base fluid. The coolant flow rate is varied in the range of 2 l/min–5 l/min. Nanocoolants exhibit enormous change in the heat transfer compared with the pure water. The heat transfer performance of CNT-water nanofluid was found to be better than Al2O3-water nanocoolant. Furthermore, the Nusselt number is found to increase with the increase in the nanoparticle concentration and nanofluid velocity.

A NEW NUMEROV-TYPE METHOD FOR COMPUTING EIGENVALUES AND RESONANCES OF THE RADIAL SCHRÖDINGER EQUATION

1996 ◽  
Vol 07 (01) ◽  
pp. 33-41 ◽  
Author(s):  
T. E. SIMOS
Keyword(s):  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
Numerical Results ◽  
New Method ◽  
Resonance Problem ◽  
Step Method ◽  
Type Method ◽  
Radial Schrödinger Equation ◽  
Better Than

A two-step method is developed for computing eigenvalues and resonances of the radial Schrödinger equation. Numerical results obtained for the integration of the eigenvalue and the resonance problem for several potentials show that this new method is better than other similar methods.

Three-Step Method with Fifth-Order Convergence for Nonlinear Equation

2013 ◽  
Vol 846-847 ◽  
pp. 1274-1277
Author(s):  
Ying Peng Zhang ◽  
Li Sun
Keyword(s):  
Nonlinear Equation ◽  
Iterative Method ◽  
Efficiency Index ◽  
Newton Methods ◽  
Order Convergence ◽  
Step Method ◽  
Second Derivatives ◽  
Fifth Order ◽  
Modified Newton Methods ◽  
Better Than

We present a fifth-order iterative method for the solution of nonlinear equation. The new method is based on two ordinary methods, which are modified Newton methods without second derivatives. Its efficiency index is 1.37973 which is better than that of Newton's method. Numerical results show the efficiency of the proposed method.

Characterization of Temperature Dependence of Interfacial Tension and Viscosity of Nanofluid

2008 ◽  
Author(s):  
S. M. Sohel Murshed ◽  
Nam-Trung Nguyen
Keyword(s):  
Surface Tension ◽  
Interfacial Tension ◽  
Temperature Dependence ◽  
Base Fluid ◽  
Deionized Water ◽  
Fluid Temperature ◽  
Interfacial Tensions ◽  
Increasing Temperature ◽  
Reduced Surface

Investigations on temperature dependence of surface tension, interfacial tension and viscosity a nanofluid are reported in this paper. Experimental results show that nanofluid having TiO2 nanoparticles (15 nm) in deionized water exhibit substantially smaller surface tension and oil-based interfacial tension than those of the base fluid (i.e. deionized water). These surface and interfacial tensions of this nanofluid were found to decrease almost linearly with increasing temperature. The Brownian motion of nanoparticles in base fluid was identified as a possible mechanism for reduced surface and interfacial tensions of nanofluid. The measured effective viscosity of nanofluid was found to be insignificantly higher than that of base fluid and it also decreases with increasing fluid temperature.

Influence of Toothbrushing on the Antierosive Effect of Film-Forming Agents

2016 ◽  
Vol 50 (2) ◽  
pp. 104-110 ◽  
Author(s):  
Taís Scaramucci ◽  
Samira Helena João-Souza ◽  
Frank Lippert ◽  
George J. Eckert ◽  
Idalina V. Aoki ◽  
...  
Keyword(s):  
Protective Effect ◽  
Sodium Fluoride ◽  
Stannous Chloride ◽  
Negative Control ◽  
Deionized Water ◽  
The Other ◽  
Surface Loss ◽  
Film Forming ◽  
Better Than

This study evaluated the influence of toothbrushing on the antierosive effect of solutions containing sodium fluoride (225 ppm/F), stannous chloride (800 ppm/Sn), sodium linear polyphosphate (2%/LPP), and their combinations, and deionized water as negative control (C). Solutions were tested in a 5-day erosion-remineralization-abrasion cycling model, using enamel and dentin specimens (n = 8). Erosion was performed 6 times/day for 5 min, exposure to the test solutions 3 times/day for 2min, and toothbrushing (or not) with toothpaste slurry 2 times/day for 2 min (45 strokes). Surface loss (SL) was determined by noncontact profilometry. Data were analyzed using three-way ANOVA (α = 0.05). Brushing caused more SL than no brushing for enamel (mean ± SD, in micrometers: 52.7 ± 6.6 and 33.0 ± 4.5, respectively), but not for dentin (28.2 ± 1.9 and 26.6 ± 1.8, respectively). For enamel without brushing, F+LPP+Sn showed the lowest SL (23.8 ± 3.4), followed by F+Sn (30.6 ± 4.9) and F+LPP (31.7 ± 1.7), which did not differ from each other. No differences were found between the other groups and C (37.8 ± 2.1). When brushing, F+LPP+Sn exhibited the lowest SL (36.7 ± 2.4), not differing from F+LPP (39.1 ± 1.8). F, F+Sn and LPP+Sn were similar (46.7 ± 2.9, 42.1 ± 2.8 and 45.3 ± 4.6, respectively) and better than C (52.7 ± 4.3). Sn (55.0 ± 2.4) and LPP (51.0 ± 4.3) did not differ from C. For dentin, neither groups differed from C, regardless of brushing. In conclusion, toothbrushing did not affect the antierosive effect of F+Sn, F+LPP and F+LPP+Sn on enamel, although overall it led to more erosion than nonbrushing. F and LPP+Sn showed a protective effect only under brushing conditions, whereas Sn and LPP did not exhibit any protection. For dentin, neither toothbrushing nor the test solutions influenced the development of erosion.

scholarly journals The Influence of the Preparation and Stability of Nanofluids for Heat Transfer

2019 ◽  
Vol 25 (4) ◽  
pp. 45-54 ◽  
Author(s):  
Noor Sabih Majeed ◽  
Basma A. Abdulmajeed ◽  
Anwar Khudhur Yaseen
Keyword(s):  
Heat Transfer ◽  
Electron Microscopy ◽  
Base Fluid ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Stability ◽  
Scanning Electron

Recently the use of nanofluids represents very important materials. They are used in different branches like medicine, engineering, power, heat transfer, etc. The stability of nanofluids is an important factor to improve the performance of nanofluids with good results. In this research two types of nanoparticles, TiO2 (titanium oxide) and γ-Al2O3 (gamma aluminum oxide) were used with base fluid water. Two-step method were used to prepare the nanofluids. One concentration 0.003 vol. %, the nanoparticles were examined. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD) were used to accomplish these tests. The stability of the two types of nanofluids is measured by zeta potential and UV-vis spectrophotometer. The results showed that γ-Al2O3/water has more stable than TiO2/ water for the same period of time.  

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