scholarly journals Thermal conductivity difference between nanofluids and micro-fluids: Experimental data and theoretical analysis using mass difference scattering

2019 ◽  
Vol 23 (6 Part B) ◽  
pp. 3797-3807
Author(s):  
Fabrizio Iacobazzi ◽  
Gianpiero Colangelo ◽  
Marco Milanese ◽  
Risi de
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Theoretical Analysis ◽  
Metal Oxides ◽  
Mass Difference ◽  
Deionized Water ◽  
Experimental Results ◽  
Experimental Campaign ◽  
Nanometric Particles ◽  
Phonon Theory

In this work, an experimental campaign on different nanofluids and micro-fluids, obtained by the dispersion of three different metal oxides (CuO, ZnO, and TiO2) with diathermic oil or deionized water has been carried out, in order to extend phonon theory to liquids, as already done in a previous work on Al2O3. Thermal conductivity of stable samples was evaluated by time. The experimental results on thermal conductivity of stable micrometric and nanometric particles suspensions in oil and water showed a further proof of mass difference scattering phenomenon.

Correlation of Theoretical Analysis With Experimental Data on The Performance of Charring Ablators

1976 ◽  
Vol 98 (1) ◽  
pp. 139-143 ◽  
Author(s):  
K. Mastanaiah
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Theoretical Analysis ◽  
Experimental System ◽  
Wall Heat Flux ◽  
System Response ◽  
Exponential Dependence ◽  
Cold Wall ◽  
Static Test

Experimental data are obtained for surface recession, char depth, and temperatures in silica phenolic and carbon phenolic ablators from static test conducted on rocket nozzles. In an attempt to correlate the theoretical analysis with the experimental observations, it is found that the effective thermal conductivity of char is strongly dependent on the wall heat flux. An hypothesis is postulated that the char conductivity can best be correlated by cold wall heat flux treated as a generalized variable that includes the effects of other factors like temperature and chemical composition of the char. Exponential dependence of char conductivity on the cold wall heat flux is observed for both the ablators, and has offered excellent comparison between the theoretical and the experimental system response.

scholarly journals Thermal Conductivity of Al2O3 and CeO2 Nanoparticles and Their Hybrid Based Water Nanofluids: An Experimental Study

2020 ◽  
Vol 65 (1) ◽  
pp. 50-60
Author(s):  
Mohammed Saad Kamel ◽  
Otabeh Al-Oran ◽  
Ferenc Lezsovits
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Volume Concentration ◽  
Experimental Models ◽  
Deionized Water ◽  
Thermal Conductivity Enhancement ◽  
Hybrid Nanofluid ◽  
Step Method ◽  
Conductivity Enhancement ◽  
Good Agreement

In many heat exchange systems, there is a demand to improve the thermal conductivity of the working fluids to make those fluids more efficient, and this can be done by dispersing solid nanomaterials into conventional liquids. In the present work, the thermal conductivity of alumina, ceria, and their hybrid with ratio (50:50) by volume-based deionized water nanofluids was experimentally measured. The nanofluids were prepared by two-step method with a range of dilute volume concentration (0.01-0.5 % Vol.), and measured at various temperatures (35, 40, 45, and 50 ºC). The experimental data for basefluid and nanofluids were verified with theoretical and experimental models, and the results have shown good agreement within the accuracy of the thermal conductivity tester. The results demonstrated that the higher thermal conductivity enhancement percentages for Al2O3, CeO2, and their hybrid nanofluids were (5.3 %, 3.3 %, and 8.8 %) at volume concentration (0.5 % Vol.) and temperature (50 ºC) compared to deionized water, respectively. Moreover, a correlation was proposed for the thermal conductivity enhancement ratio of the hybrid nanofluid and showed good accuracy with measured experimental data.

scholarly journals Numerical Simulations with RELAP5-3D and RELAP5/mod3.3 of the Second Experimental Campaign on In-Box LOCA Transients for HCLL TBS

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4544
Author(s):  
Alessandro Venturini ◽  
Marco Utili ◽  
and Nicola Forgione
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Literature Review ◽  
Numerical Simulations ◽  
Thermophysical Properties ◽  
Pressure Wave ◽  
Experimental Results ◽  
Experimental Campaign ◽  
Maximum Value ◽  
Lead Bismuth Eutectic

In-box LOCA was identified as one of the worst accidental scenarios for the HCLL TBS (Helium Cooled Lithium-Lead Test Blanket System). Aiming to experimentally analyze the consequences of this transient, ENEA designed and built THALLIUM (Test HAmmer in Lead LIthiUM), a facility that reproduces the LiPb loop of the HCLL TBS. Two experimental campaigns were carried out by simulating the rupture of a stiffening plate and the related helium injection in the LiPb loop. The obtained experimental data were used to check the capabilities of RELAP5 system code to reproduce the pressure wave propagation that follows this accident. The first simulations were made with RELAP5-3D using LBE (Lead–Bismuth Eutectic) as a system fluid, as the thermophysical properties of LiPb are tabulated only up to a maximum value of 40 bar in this version of the code. Then, LiPb properties were implemented in RELAP5/mod3.3, after selecting the proper correlations from a literature review. This work summarizes the numerical simulations of the second experimental campaign, which was simulated with both versions of the code. The simulations highlight that the code is able to accurately reproduce the experimental results and that RELAP5-3D is slightly more precise than RELAP5/mod3.3 in predicting the pressure trends.

Analysis and Experimental Verification on Bias Drift of Silicon Microgyroscope

2014 ◽  
Vol 670-671 ◽  
pp. 1305-1309
Author(s):  
Wei Feng Tang ◽  
An Ping Qiu ◽  
Guo Ming Xia ◽  
Yan Su
Keyword(s):  
Experimental Data ◽  
Theoretical Analysis ◽  
Relative Error ◽  
Experimental Verification ◽  
Output Voltage ◽  
Structure Design ◽  
Experimental Results ◽  
Theoretical Formula ◽  
Bias Drift ◽  
Experimental Bias

There is a bias drift of silicon microgyroscope when power on which limits its application in higher precision field. This paper analyzes and validates the main cause of bias drift, combined with theoretical analysis of demodulation and experimental results, which has a great significance for improving the performance of silicon microgyroscope. First of all, operating principle of silicon microgyroscope is introduced and theoretical analysis on bias drift is made on the basis of DC output voltage of microgyroscope. Secondly, demodulated signals’ amplitude and phase are analyzed in Matlab with the experimental data. By contrasting theoretical and experimental bias drift, the accuracy of theoretical formula is verified. It turns out that, the relative error of bias drift from 2-hours value to stable value is 5.5%, it’s 6.6% for 1-hour value to stable value and for beginning it’s just 1.7%. Experimental results agrees well with the theoretical analysis, which verifies that the main cause of bias drift of silicon microgyroscope is the phase difference between Vds and Vsense. This conclusion can provide some guidance for structure design optimization and circuits improving.

Oblique weir equation using incomplete self-similarity

2006 ◽  
Vol 33 (10) ◽  
pp. 1241-1250 ◽  
Author(s):  
S M Borghei ◽  
A R Kabiri-Samani ◽  
N Nekoee
Keyword(s):  
Experimental Data ◽  
Data Analysis ◽  
Theoretical Analysis ◽  
Computer Program ◽  
Key Words ◽  
Dimensional Analysis ◽  
Flow Characteristics ◽  
Experimental Results ◽  
Trial And Error ◽  
Self Similarity

Incomplete self-similarity (ISS) concept is employed to develop the equations from existing experimental results of flow over an oblique rectangular sharp-crested weir for both free and submerged flow. The stage-discharge relationship is obtained by theoretical analysis, based on the application of the dimensional analysis and the ISS theory. For analysis, the relations were found by trial and error procedure using the SPSS mathematical computer program that estimates the relation among multi-variable functions. Thus, equations to estimate the flow characteristics for both free and submerged flow are proposed. The results show a better compatibility with the experimental data than the previous equations given by the main author. Hence, the capabilities of ISS method for similar analysis and the powerful program of SPSS for multi-variable data analysis is shown. Finally, design guides together with examples are presented to show the simple use of the graphs obtained . Key words: dimensional analysis, incomplete self-similarity (ISS), oblique weir, experimental data.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals A Novel Gate Drive Circuit for Suppressing Turn-on Oscillation of Non-Kelvin Packaged SiC MOSFET

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2449
Author(s):  
Hongyan Zhao ◽  
Jiangui Chen ◽  
Yan Li ◽  
Fei Lin
Keyword(s):  
Thermal Conductivity ◽  
Breakdown Voltage ◽  
Basic Principle ◽  
Double Pulse ◽  
Experimental Results ◽  
Switching Frequency ◽  
Turn On ◽  
Proof Testing ◽  
Gate Driver ◽  
Drive Circuit

Compared with a silicon MOSFET device, the SiC MOSFET has many benefits, such as higher breakdown voltage, faster action speed and better thermal conductivity. These advantages enable the SiC MOSFET to operate at higher switching frequencies, while, as the switching frequency increases, the turn-on loss accounts for most of the loss. This characteristic severely limits the applications of the SiC MOSFET at higher switching frequencies. Accordingly, an SRD-type drive circuit for a SiC MOSFET is proposed in this paper. The proposed SRD-type drive circuit can suppress the turn-on oscillation of a non-Kelvin packaged SiC MOSFET to ensure that the SiC MOSFET can work at a faster turn-on speed with a lower turn-on loss. In this paper, the basic principle of the proposed SRD-type drive circuit is analyzed, and a double pulse platform is established. For the purpose of proof-testing the performance of the presented SRD-type drive circuit, comparisons and experimental verifications between the traditional gate driver and the proposed SRD-type drive circuit were conducted. Our experimental results finally demonstrate the feasibility and effectiveness of the proposed SRD-type drive circuit.

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