Numerical Analysis of Nanofluids in Heat Pipe

2011 ◽  
Author(s):  
Pawan K. Singh ◽  
Nouman Zahoor Ahmed ◽  
Mohamed Ibrahim Ali ◽  
Youssef Shatilla
Keyword(s):  
Numerical Analysis ◽  
Heat Pipe ◽  
Mass Flow ◽  
Flow Rate ◽  
Volume Fraction ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
The Other ◽  
Software Modeling ◽  
Homogeneous Fluid

The numerical analysis of nanofluids in heat pipe is investigated using CFD, computational fluid dynamics, software modeling, FLUENT. The modeling was completed for base fluids and validated against earlier study. The alumina-water nanofluids are used for the investigation due to availability of huge literature. The thermal conductivity and viscosity are evaluated on the basis of literature and used in the study. For the other thermo-physical properties such as density and specific heat, mass based mixture model approach has been used. To see the concentration effect of nanofluids, mixtures with volume fraction of 1, 2, 3 and 5% are considered. The nanofluids mixture assumed to be homogeneous fluid flow in this simulation. The inlet velocity boundary condition, BC, is given by two approaches, mass flow arte and volume flow rate. The results showed that the nanofluids performance is similar to the base fluids while inlet BC is constant volume flow rate. On the other hand, nanofluids enhanced the performance over the base fluid while constant mass flow rate BC is used.

scholarly journals NATURAL GAS HEAT COMBUSTION DETERMINATION ON MEASURING SYSTEMS WITH DUPLICATE GAS UNITS

2020 ◽  
Author(s):  
Igor Petryshyn ◽  
◽  
Olexandr Bas ◽  
◽  
Keyword(s):  
Natural Gas ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Molar Fraction ◽  
Volume Flow ◽  
Combustion Heat ◽  
Measuring Systems ◽  
Gas Volume

The paper focuses on the need to determine the natural gas heat combustion in order to transition to gas metering in units of energy. The technical organization of gas transportation in the main and distribution pipelines on the territory of Ukraine is shown. A detailed analysis of regulatory and legal support, which regulates the definition and accounting of quantitative and qualitative characteristics of natural gas at gas metering units. The draft Rules for determining the natural gas volume are considered in detail. Specified variants of determining the weighted average value of combustion heat in the case of complex gas supply systems with the use of flow measuring means of gas combustion heat. The necessity and urgency of determining the natural gas heat combustion on measuring systems, which are equipped with duplicate metering units without the installation flow means measuring the heat combustion. Emphasis is placed on the fact that a large number of measuring systems are built on the method of variable pressure drop with the use of standard orifice devices. It is pointed out that this method, according to its physical principle, measures the mass gas flow rate. It is also stipulated that ultrasonic gas meters are often used to complete duplicate metering units. The advantages of ultrasonic meters are given. Attention is drawn to the availability of technical metrological support in Ukraine on the basis calibration prover, which includes two secondary standards gas volume and volume flow rate units. Methods and technical means for determining the natural gas heat combustion are analyzed. The calculation of the gas heat combustion and the Wobbe number based on the density values is shown. It is noted that the value of the gas mass flow rate is related to the value of the gas volume flow rate precisely the value of density. The nonlinear dependence of the gas mass heat combustion for the density, which is associated with a disproportionate change in the percentage of carbon atoms to hydrogen atoms, is shown. The structural scheme of the measuring system with the duplicating metering unit for gas density definition and gas heat combustion calculation is developed. The density calculation and natural gas heat combustion depending on the molar fraction of nitrogen and carbon dioxide in the gas from the minimum to the maximum value is carried out. The linear dependence of the change in the gas heat combustion for the molar fraction of nitrogen is established, on the basis of which the method of controlling the gas heat combustion for measuring systems with a duplicate metering unit is proposed. It is shown that the developed procedure for determining the natural gas heat combustion based on the value of density, which is obtained from the calculation of gas mass flow rate and gas volume flow rate consumption on measuring systems with duplicate metering units exactly satisfies class B and C according to DSTU OIML R 140.

A Comparison of Two Alternative Methods for Defining Fan Performance

1982 ◽  
Vol 104 (1) ◽  
pp. 177-183 ◽  
Author(s):  
P. M. Gerhart ◽  
R. Jorgensen ◽  
J. Kroll
Keyword(s):  
Flow Rate ◽  
Total Pressure ◽  
Performance Test ◽  
Static Pressure ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
The Other ◽  
Alternative Methods ◽  
Performance Variables ◽  
Fan Performance

PTC 11 Committee, the ASME Performance Test Code Committee charged with producing a new test code for large industrial fans, has decided to present code users with two options for expressing fan performance. While one of these options is representative of current U.S. practice, the other option appears to be quite different. The differences center around the definitions of fan flow rate and fan output. Historically, fan flow rate has been defined as the volume flow rate at the fan inlet, and fan output has been defined as either the rise in total pressure across the fan or as the rise from the total pressure at the inlet to the static pressure at the outlet. The alternative method uses the mass flow rate and the “fan specific energy” as the performance variables. If the fan process is incompressible, the two sets of variables produce easily reconciled values; however, if compressibility must be accounted for, subtle differences may arise. This paper examines the assumptions and developments of the two alternative methods of expressing fan performance.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

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