The Effect of Quaternary Treatment Under Varied Ratios of Weight-Volume-Concentration on the Bacteriostatic Property of Fabrics

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat are rather limited. In the study of the heat transfer performance of nanofluids, it is necessary to increase the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA method, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Method: The two-step method was used in the preparation of nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

Download Full-text

Improved separation of C12-C22 fatty acid phenacyl esters by reversed phase column liquid chromatography

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862722 ◽

1986 ◽

Vol 51 (12) ◽

pp. 2722-2726 ◽

Cited By ~ 3

Author(s):

Tomáš Haniš ◽

Miroslav Smrž ◽

Pavel Klír ◽

Karel Macek ◽

Zdeněk Deyl

Keyword(s):

Volume Concentration ◽

Gradient Elution ◽

Reversed Phase ◽

Isocratic Elution ◽

Water Gradient ◽

Phenacyl Esters ◽

Acetonitrile Concentration ◽

Phase Column ◽

Reversed Phase Column ◽

Critical Pairs

Phenacyl esters of C12-C22 fatty acids were separated on Separon SGX C18 column, using a gradient elution with methanol-acetonitrile-water. The proposed gradient showed better resolution of the critical pairs C18:3-C14:0, C16:1-C20:4, and C16:0-C18:1 than the gradient elution with methanol-water or acetonitrile-water, or than the isocratic elution with methanol-acetonitrile-water. The optimum volume concentration (83%) of the sum of both methanol and acetonitrile was maintained constant for 35 min; in this period the acetonitrile concentration decreased linearly from the initial 42-60% to 0% while the methanol concentration increased from the initial 41-23% to 83% at the same rate. After 35 min the elution was completed with a methanol-water gradient. The whole analysis can be performed within 63 min at a flow rate 1 ml/min.

Download Full-text

Direct Measurement of Stress at the Base of a Glacier

Journal of Glaciology ◽

10.1017/s0022143000014027 ◽

1979 ◽

Vol 22 (86) ◽

pp. 3-24 ◽

Cited By ~ 39

Author(s):

G. S. Boulton ◽

E. M. Morris ◽

A. A. Armstrong ◽

A. Thomas

Keyword(s):

Shear Stress ◽

Volume Concentration ◽

Normal Pressure ◽

Spatial Average ◽

Short Term ◽

Overburden Pressure ◽

Basal Ice ◽

Debris Particles ◽

Or Groups ◽

Pressure Changes

AbstractContact stress transducers were placed in subglacial bedrock and used to monitor continuously shear stress and normal pressure changes at the contact with the overriding glacier sole 100 m beneath the surface of the Glacier d’Argentière during periods in summer 1973 and spring 1975. The measured fluctuations in normal pressure and shear stress do not appear to be related to changes in sliding velocity. Analysis of the data reveals short-term fluctuations in normal pressure and shear stress which appear to be related to the passage of individual large debris particles or groups of particles over the transducer. The shear stress appears to be a function of the volume concentration of debris in the ice. The volume concentration at any point appears to be partially dependent on a “streaming” process by which basal debris-rich ice tends to flow around the lateral flanks of hummocks on the glacier bed. Where sub-glacial cavities occur, this streaming effect appears to be dependent on the extent of cavitation and thus on ice overburden pressure and velocity. It is suggested that this process can account for an apparent lag between changes in normal pressure and shear stress.The maximum ratio between shear and normal stress averaged over a period of 10 min was 0.44. This is equivalent to a spatial average over 0.3 cm. Debris concentrations in basal ice of up to 43% by volume occurred. It is suggested that concentrations of this order are common at the base of temperate glaciers and thus that a significant part of the drag at the base of a glacier may be contributed by frictional interactions between the basal-debris load and the bed.

Download Full-text

Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.922 ◽

2014 ◽

Vol 592-594 ◽

pp. 922-926 ◽

Cited By ~ 5

Author(s):

Devasenan Madhesh ◽

S. Kalaiselvam

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Volume Concentration ◽

Thermal Characteristics ◽

Hybrid Nanofluid ◽

Tubular Heat Exchanger ◽

Overall Heat Transfer Coefficient ◽

Flow Through ◽

Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

Download Full-text

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.832.160 ◽

2013 ◽

Vol 832 ◽

pp. 160-165 ◽

Cited By ~ 16

Author(s):

Mohammad Alam Khairul ◽

Rahman Saidur ◽

Altab Hossain ◽

Mohammad Abdul Alim ◽

Islam Mohammed Mahbubul

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Heat Exchanger ◽

Pressure Drop ◽

Transfer Coefficient ◽

Friction Factor ◽

Heat Exchangers ◽

Heat Transfer Performance ◽

Volume Concentration ◽

Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Download Full-text

Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Nanomaterials ◽

10.3390/nano11010136 ◽

2021 ◽

Vol 11 (1) ◽

pp. 136

Author(s):

Solomon O. Giwa ◽

Mohsen Sharifpur ◽

Mohammad H. Ahmadi ◽

S. M. Sohel Murshed ◽

Josua P. Meyer

Keyword(s):

Electrical Conductivity ◽

Visual Inspection ◽

Volume Concentration ◽

Working Fluid ◽

Hybrid Nanofluid ◽

Multiwalled Carbon ◽

Transmission Electron ◽

Hybrid Nanofluids ◽

Uv Visible ◽

The Stability

The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

Download Full-text

Settling Behavior of Particles in Bubble Containing Newtonian Fluids: Experimental Study and Model Development

10.1115/omae2021-62756 ◽

2021 ◽

Author(s):

Silin Jing ◽

Xianzhi Song ◽

Zhaopeng Zhu ◽

Buwen Yu ◽

Shiming Duan

Keyword(s):

Reynolds Number ◽

Drag Coefficient ◽

Volume Concentration ◽

Settling Velocity ◽

Particle Density ◽

Particle Diameter ◽

Newtonian Fluids ◽

Spherical Particles ◽

Bubble Volume ◽

Particle Reynolds Number

Abstract Accurate description of cuttings slippage in the gas-liquid phase is of great significance for wellbore cleaning and the control accuracy of bottom hole pressure during MPD. In this study, the wellbore bubble flow environment was simulated by a constant pressure air pump and the transparent wellbore, and the settling characteristics of spherical particles under different gas volume concentrations were recorded and analyzed by highspeed photography. A total of 225 tests were conducted to analyze the influence of particle diameter (1–12mm), particle density (2700–7860kg/m^3), liquid viscosity and bubble volume concentration on particle settling velocity. Gas drag force is defined to quantitatively evaluate the bubble’s resistance to particle slippage. The relationship between bubble drag coefficient and particle Reynolds number is obtained by fitting the experimental results. An explicit settling velocity equation is established by introducing Archimedes number. This explicit equation with an average relative error of only 8.09% can directly predict the terminal settling velocity of the sphere in bubble containing Newtonian fluids. The models for predicting bubble drag coefficient and the terminal settling velocity are valid with particle Reynolds number ranging from 0.05 to 167 and bubble volume concentration ranging from 3.0% to 20.0%. Besides, a trial-and-error procedure and an illustrative example are presented to show how to calculate bubble drag coefficient and settling velocity in bubble containing fluids. The results of this study will provide the theoretical basis for wellbore cleaning and accurate downhole pressure to further improve the performance of MPD in treating gas influx.

Download Full-text