scholarly journals Design and Fabrication of a Microfluidic Viscometer Based on Electrofluidic Circuits

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 375 ◽  
Author(s):  
Bo-Bi Tzeng ◽  
Yung-Shin Sun
Keyword(s):  
Pressure Drop ◽  
Pure Water ◽  
Sample Pretreatment ◽  
Pdms Membrane ◽  
Hydraulic Pressure ◽  
Pdms Layer ◽  
Glycerol Water ◽  
Voltage Difference ◽  
Measured Voltage ◽  
Liquid Samples

This paper reports a microfluidic viscometer based on electrofluidic circuits for measuring viscosities of liquid samples. The developed micro-device consists of a polydimethylsiloxane (PDMS) layer for electrofluidic circuits, a thin PDMS membrane, another PDMS layer for sample pretreatment, and a glass substrate. As the sample flows inside the microfluidic channel, its viscosity causes flow resistance and a pressure drop along this channel. This pressure drop, in turn, generates a hydraulic pressure which deforms the PDMS membrane, causing changes in the cross-sectional area and the electrical resistance of the electrofluidic resistor. This small resistance change is then measured via the electrofluidic Wheatstone bridge to relate the measured voltage difference to the fluidic viscosity. The performance of this viscometer was first tested by flowing nitrogen gas with controllable pressures into the device. The relationship between measured voltage difference and input gas pressure was analyzed to be linear in the pressure range of 0–15 psi. Another test using pure water indicated good linearity between measured voltage difference and flow rate in the rate range of 20–100 μL/min. Viscosities of glycerol/water solutions with volume/volume (v/v) concentrations ranging from 0 to 30% were measured, and these values were close to those obtained using commercially available viscometers. In addition, the sample-pretreatment layer can be used to mix and/or dilute liquid samples to desired concentrations. Therefore, this microfluidic device has potential for measurements of fluidic viscosity in a fast, accurate, and high-throughput manner.

scholarly journals Simulation approach on turbulent thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ing Jiat Kendrick Wong ◽  
Ngieng Tze Angnes Tiong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Hybrid Nanofluid ◽  
Performance Factor ◽  
Thermal Performance Factor ◽  
The Heat Transfer Coefficient

AbstractThis paper presents the numerical study of thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts (square and rectangular). Turbulent regime is studied with the Reynolds number ranges from 10000 to 100000. The heat transfer performance and flow behaviour of hybrid nanofluid are investigated, considering the nanofluid volume concentration between 0.1 and 2%. The thermal performance factor of hybrid nanofluid is evaluated in terms of performance evaluation criteria (PEC). This present numerical results are successfully validated with the data from the literature. The results indicate that the heat transfer coefficient and Nusselt number of Al2O3-Cu/water hybrid nanofluid are higher than those of Al2O3/water nanofluid and pure water. However, this heat transfer enhancement is achieved at the expense of an increased pressure drop. The heat transfer coefficient of 2% hybrid nanofluid is approximately 58.6% larger than the value of pure water at the Reynolds number of 10000. For the same concentration and Reynolds number, the pressure drop of hybrid nanofluid is 4.79 times higher than the pressure drop of water. The heat transfer performance is the best in the circular pipe compared to the non-circular ducts, but its pressure drop increment is also the largest. The hybrid nanofluid helps to improve the problem of low heat transfer characteristic in the non-circular ducts. In overall, the hybrid nanofluid flow in circular and non-circular ducts are reported to possess better thermal performance factor than that of water. The maximum attainable PEC is obtained by 2% hybrid nanofluid in the square duct at the Reynolds Number of 60000. This study can help to determine which geometry is efficient for the heat transfer application of hybrid nanofluid.

scholarly journals Design and Simulation of Nozzle for Pure Water Jet Portable Cutting Tool

2019 ◽  
Vol 8 (12S2) ◽  
pp. 703-706
Keyword(s):  
Pressure Drop ◽  
Cross Sections ◽  
Pure Water ◽  
Water Jet ◽  
Element Analysis ◽  
Cutting Machine ◽  
Water Jet Cutting ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
The Impact

A pure water jet at subsonic speed provides an opportunity for application in cutting soft material with the advantage of not contaminating the workpiece. Inside the nozzle, water is flowing through various cross sections, which lead to pressure drop and loss of energy. This requires a nozzle with a design that causes minimum pressure drop. In this work, Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) were used to analyse the flow through five different nozzles. For each nozzle, the pressures of 10 MPa, 20 MPa and 30 MPa were applies at the inlet. For the inlet pressure of 10 MPa, the highest outlet velocity us 136.12 m/s at the pressure of 9.261 MPa. The impact pressure at stand distance of 0.5 mm and 1.0 mm were 8.26 MPa and 8.02 MPa, respectively. For this nozzle, the Factor of Safety for 10 MPa, 20 MPa and 30 MPa were 6.4, 3.2 and 2.961, respectively. The findings are relevant to the development of pure water jet cutting machine

Solvothermal Preparation of Nano-Sized CaWO4 Particles

2007 ◽  
Vol 124-126 ◽  
pp. 1265-1268 ◽  
Author(s):  
Sulawan Kaowphong ◽  
Titipun Thongtem ◽  
Somchai Thongtem
Keyword(s):  
Pure Water ◽  
Solvothermal Reaction ◽  
Hrtem Image ◽  
Scheelite Structure ◽  
Glycerol Water ◽  
Calcium Salts ◽  
Solvothermal Preparation

CaWO4 was prepared by solvothermal reaction of Na2WO4.2H2O and calcium salts (CaCl2.2H2O, Ca(NO3)2.4H2O and Ca(CH3COO)2) in solvent containing a variety of glycerol/water ratios at 160 oC for 6 h. By using XRD, SEM, TEM and ED, the products compose of nano-sized CaWO4 particles with scheelite structure but different morphologies. Interplanar spaces between (101) planes were determined from HRTEM image, ED patterns and XRD spectra are 0.424, 0.474 and 0.476 nm, respectively. Luminescent intensities of the products prepared in pure water are the highest and their central peaks are the same at 444 nm. In addition, Ca, W and O were detected using EDX.

Convective Heat Transfer Characteristics of Silver-Water Nanofluid Under Laminar and Turbulent Flow Conditions

2012 ◽  
Vol 4 (3) ◽  
Author(s):  
Lazarus Godson ◽  
B. Raja ◽  
D. Mohan Lal ◽  
S. Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Pure Water ◽  
Convective Heat Transfer Coefficient ◽  
Experimental Results

The convective heat transfer coefficient and pressure drop of silver-water nanofluids is measured in a counter flow heat exchanger from laminar to turbulent flow regime. The experimental results show that the convective heat transfer coefficient of the nanofluids increases by up to 69% at a concentration of 0.9 vol. % compared with that of pure water. Furthermore, the experimental results show that the convective heat transfer coefficient enhancement exceeds the thermal conductivity enhancement. It is observed that the measured heat transfer coefficient is higher than that of the predicted ones using Gnielinski equation by at least 40%. The use of the silver nanofluid has a little penalty in pressure drop up to 55% increase 0.9% volume concentration of silver nanoparticles.

Fouling propensity of forward osmosis: investigation of the slower flux decline phenomenon

2010 ◽  
Vol 61 (4) ◽  
pp. 927-936 ◽  
Author(s):  
Winson C. L. Lay ◽  
Tzyy Haur Chong ◽  
Chuyang Y. Tang ◽  
Anthony G. Fane ◽  
Jinsong Zhang ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Ambient Pressure ◽  
Pure Water ◽  
Forward Osmosis ◽  
Hydraulic Pressure ◽  
Contributing Factors ◽  
Draw Solution ◽  
Flux Decline ◽  
Internal Concentration ◽  
Quality Water

Forward Osmosis (FO) is a membrane process that uses the natural osmotic pressure of a concentrated draw solution to extract pure water from a feed stream. The attraction of the FO process is that it uses dense membranes, while operating at ambient pressure. This means that the FO process could potentially produce high quality water with lower energy consumption, as compared to the other desalination or reclamation processes. As FO does not entail the use of hydraulic pressure, FO has been hypothesized to have lower fouling propensity than pressure driven membrane processes. Membrane fouling has significant impact on the operational sustainability and economics of the process. This study examines the possible contributing factors to the slower flux decline observed in FO experiments based on a combined experimental and modelling approach. It was found that these factors could include low water fluxes, use of hydrophilic and smooth membranes, and the effect of internal concentration polarisation that is inherent of FO. It was also found that the transmission of draw solutes from the draw solution into the feed can have significant effect on FO performance.

scholarly journals A Study on Distribution Measurement and Mechanism of Deformation due to Water Loss of Overburden Layer in Vertical Shaft

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chunde Piao ◽  
Jun Yuan ◽  
Dangliang Wang ◽  
Pengtao Li
Keyword(s):  
Pressure Drop ◽  
Optical Fiber ◽  
Water Loss ◽  
Test Method ◽  
Hydraulic Pressure ◽  
Vertical Shaft ◽  
Fiber Sensing ◽  
Sensing Technology ◽  
Water Head ◽  
Optical Fiber Sensing

Based on FBG fiber Bragg grating technology and BOTDA distributed optical fiber sensing technology, this study uses fine sand to simulate overburden layer in vertical shaft model equipment. It studies the placing technique and test method for optical fiber sensors in the overburden layer, combined with MODFLOW software to simulate the change of the water head value when the overburden layer is losing water, and obtains the deformation features of overburden layer. The results show, at the beginning of water loss, the vertical deformation increases due to larger hydraulic pressure drop, while the deformation decreases gradually and tends to be stable with the hydraulic pressure drop reducing. The circumferential deformation is closely related to such factors as the distance between each drainage outlet, the variations of water head value, and the method of drainage. The monitoring result based on optical fiber sensing technology is consistent with the characteristics of water loss in overburden layer simulated by MODFLOW software, which shows that the optical fiber sensing technology applied to monitor shaft overburden layer is feasible.

scholarly journals Investigation of Counterflow Microchannel Heat Exchanger with Hybrid Nanoparticles and PCM Suspension as a Coolant

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Mushtaq I. Hasan ◽  
Mohammad J. Khafeef ◽  
Omid Mohammadi ◽  
Suvanjan Bhattacharyya ◽  
Alibek Issakhov
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Pure Water ◽  
Thermal Characteristics ◽  
Hybrid Nanoparticles ◽  
Working Fluid ◽  
Microchannel Heat Exchanger ◽  
Noticeable Increase ◽  
Nanoparticles Concentration

The effect of the hybrid suspension on the intrinsic characteristics of microencapsulated phase change material (MEPCM) slurry used as a coolant in counterflow microchannel heat exchanger (CFMCHE) with different velocities is investigated numerically. The working fluid used in this paper is a hybrid suspension consisting of nanoparticles and MEPCM particles, in which the particles are suspended in pure water as a base fluid. Two types of hybrid suspension are used (Al2O3 + MEPCM and Cu + MEPCM), and the hydrodynamic and thermal characteristics of these suspensions flowing in a CFMCHE are numerically investigated. The results indicated that using hybrid suspension with high flow velocities improves the performance of the microchannel heat exchanger while resulting in a noticeable increase in pressure drop. Thereupon, it causes a decrease in the performance index. Moreover, it was found that the increment of the nanoparticles’ concentration can rise the low thermal conductivity of the MEPCM slurry, but it also leads to a noticeable increase in pressure drop. Furthermore, it was found that as the thermal conductivity of Cu is higher than that for Al2O3, the enhancement in heat transfer is higher in case of adding Cu particles compared with Al2O3 particles. Therefore, the effectiveness of these materials depends strongly on the application at which CFMCHE is employed.

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