scholarly journals ESTIMATIVA DO COEFICIENTE DE EXPANSÃO TÉRMICA DE MISTURAS DE ÓLEO DIESEL E ÓLEO DE SOJA RESIDUAL

e-xacta ◽  
2013 ◽  
Vol 6 (1) ◽  
pp. 67
Author(s):  
César Augusto Canciam
Keyword(s):  
Thermal Expansion ◽  
Regression Analysis ◽  
Linear Regression ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Alternative Energy ◽  
Linear Regression Analysis ◽  
Diesel Oil ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

<p align="justify">A utilização de óleos vegetais residuais como fonte de energia alternativa vem ganhando espaço investigativo no Brasil, principalmente na produção de biocombustíveis e de misturas combustíveis com óleo diesel. O presente trabalho teve por objetivo estimar o coeficiente de expansão térmica de misturas de óleo diesel (OD) e óleo de soja residual (OSR) a partir da modelagem matemática de dados da massa específica em função da temperatura. As misturas estudadas foram: mistura 1 (25% OSR + 75% OD), mistura 2 (50% OSR + 50% OD) e mistura 3 (75% OSR + 25% OD). O intervalo de temperatura considerado foi de 25 a 90ºC. Para a estimativa do coeficiente de expansão térmica foi realizada uma análise de regressão linear. Os valores do coeficiente de expansão térmica encontrados foram 7,7508 x 10-4ºC-1 (para a mistura 1), 8,3355 x 10-4ºC-1 (para a mistura 2) e 8,2249 x 10-4ºC-1(para a mistura 3). Nas análises de regressão linear, os coeficientes de correlação foram próximos da unidade, indicando que para cada mistura a correlação é classificada como muito forte. A ausência na literatura de valores do coeficiente de expansão térmica para misturas OD + OSR dificultou a comparação com os valores encontrados.</p><p align="justify">Abstract</p><p align="justify">The use of residual vegetable oils as an alternative energy source is gaining momentum investigative in Brazil, mainly in the production of biofuels and blends with Diesel oil. This study aimed to estimative the thermal expansion coefficient of mixtures of Diesel oil (DO) and residual soybean oil (RSO) from the mathematical modeling of data of specific weight as a function of temperature. The mixture 1 (25% RSO + 75% DO), mixture 2 (50% RSO + 50% DO) and mixture 3 (75% RSO + 25% DO) were studied. The temperature range considered was 25 to 90ºC. A linear regression analysis was performed to estimative the values of the thermal expansion coefficient. The thermal expansion coefficients were 7.7508 x 10-4 ºC-1 (for the mixture 1), 8.3355 x 10-4 ºC-1 (for the mixture 2) and 8.2249 x 10-4 ºC-1 (for the mixture 3). In linear regression analysis, the correlation coefficients were close to unity, indicating that the correlation for each mixture is classified as very strong. The absence in the literature of the thermal expansion coefficients of the mixtures DO + RSO made it difficult the comparing with the values found.</p>

Measurement of thermal expansion coefficient of substrate GGG and its epitaxial layer YIG

1999 ◽  
Vol 14 (1) ◽  
pp. 2-4 ◽  
Author(s):  
Rui-sheng Liang ◽  
Feng-chao Liu
Keyword(s):  
Thin Film ◽  
Thermal Expansion ◽  
Single Crystal ◽  
Thermal Expansion Coefficient ◽  
Epitaxial Layer ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
New Method ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

A new method is used in measuring the linear thermal expansion coefficients in composite consisting of a substrate Gd3Ga2Ga3O12 (GGG) and its epitaxial layer Y3Fe2Fe3O12 (YIG) within the temperature range 13.88 °C–32.50 °C. The results show that the thermal expansion coefficient of GGG in composite is larger than that of the GGG in single crystal; the thermal expansion coefficient of thick film YIG is also larger than that of thin film. The results also show that the thermal expansion coefficient of a composite consisting of film and its substrate can be measured by using a new method.

scholarly journals Twisted Fibers Can Have an Adjustable Thermal Expansion

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 456
Author(s):  
Donghua Yue ◽  
Liming Wei
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Carbon Fibers ◽  
Expansion Coefficient ◽  
Twist Angle ◽  
Capacitive Sensor ◽  
Model Calculations ◽  
Thermal Expansion Coefficients ◽  
Geometrical Features ◽  
Expansion Coefficients

In this paper, a device with high accuracy capacitive sensor (with the error of 0.1 micrometer) is constructed to measure the axial thermal expansion coefficent of the twisted carbon fibers and yarns of Kevlar. A theoretical model based on the thermal elasticity and the geometrical features of the twisted structure is also presented to predict the axial expansion coefficient. It is found that the twist angle, diameter and pitch have remarkable influences on the axial thermal expansion coefficients of the twisted carbon fibers and Kevlar strands, and the calculated results are in good agreement with experimental data. We found that, with the increase of the twist angle, the absolute value of the axial thermal expansion coefficient increases. For the Kevlar samples, the expansion coefficient will grow by about 46% when the twist angle increases from 0 to 25 degrees, while the carbon fiber samples will grow by about 72% when the twist angle increases from 0 to 35 degrees. The experimental measurements and the model calculations reveal important properties of the thermal expansion in the twisted structures. Most notably, the expansion of the strand during heating or cooling can be zero when the twist angle is around β = arcsin(αL/αT)^1/2, where β denotes twist angle of the strand and αL, αT are the longitute and the transverse thermal expansion coefficient of the strand, respectively. According to the present experiments and analyses, a method to control the axial thermal expansion coefficient of this new kind of twisted structure is proposed. Moreover, the mechanism of this tunable thermal expansion is discussed. Based on the model, a method that can be used to rectify the thermal expansion properties of the twist structures is established. This may be a new way of fabricating zero expansion composite materials in the future.

Thermal expansion coefficients of a binary alloy Ni80Zr20 at elevated temperatures

1984 ◽  
Vol 17 (5) ◽  
pp. 359-360
Author(s):  
S. K. Shadangi ◽  
U. K. Shadangi ◽  
S. C. Panda
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Elevated Temperatures ◽  
Intermetallic Phase ◽  
Lattice Parameter ◽  
Solid Solution Phase ◽  
Linear Variation ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The Debye–Scherrer pattern of the alloy Ni80Zr20 clearly shows the presence of a nickel solid-solution phase along with a new intermetallic phase Ni23Zr6, which seems to be isostructural with the Co23Zr6 phase. The thermal expansion coefficient of the Ni23Zr6 phase has been investigated in the temperature range 1003–1493 K. Linear variation of lattice parameter with temperature has been observed. The thermal expansion coefficient remains almost constant throughout this temperature interval.

scholarly journals Thermal expansion coefficient of few-layer MoS2 studied by temperature-dependent Raman spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhongtao Lin ◽  
Wuguo Liu ◽  
Shibing Tian ◽  
Ke Zhu ◽  
Yuan Huang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Negative Thermal Expansion ◽  
Thermal Parameter ◽  
Temperature Dependent ◽  
Bending Vibrations ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

AbstractThe thermal expansion coefficient is an important thermal parameter that influences the performance of nanodevices based on two-dimensional materials. To obtain the thermal expansion coefficient of few-layer MoS2, suspended MoS2 and supported MoS2 were systematically investigated using Raman spectroscopy in the temperature range from 77 to 557 K. The temperature-dependent evolution of the Raman frequency shift for suspended MoS2 exhibited prominent differences from that for supported MoS2, obviously demonstrating the effect due to the thermal expansion coefficient mismatch between MoS2 and the substrate. The intrinsic thermal expansion coefficients of MoS2 with different numbers of layers were calculated. Interestingly, negative thermal expansion coefficients were obtained below 175 K, which was attributed to the bending vibrations in the MoS2 layer during cooling. Our results demonstrate that Raman spectroscopy is a feasible tool for investigating the thermal properties of few-layer MoS2 and will provide useful information for its further application in photoelectronic devices.

scholarly journals Testing Contraction and Thermal Expansion Coefficient of Construction and Moulding Polymer Composites

2018 ◽  
Vol 25 (s1) ◽  
pp. 151-158 ◽  
Author(s):  
Łukasz Pyrzowski
Keyword(s):  
Thermal Expansion ◽  
Polymer Composites ◽  
Thermal Expansion Coefficient ◽  
Technological Process ◽  
Expansion Coefficient ◽  
Material Properties ◽  
Design Stage ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Materials Used

Abstract The paper presents results of systematic tests of contraction and thermal expansion coefficients of materials based on polymer composites. The information on the above material properties is essential both at the design stage and during the use of finished products. Components for the samples were selected in such a way as to represent typical materials used for production of construction and moulding elements. The performed tests made it possible to monitor the analysed parameters at different stages of the technological process.

scholarly journals Is there a layer deep in the Earth that uncouples heat from mechanical work?

2014 ◽  
Vol 6 (1) ◽  
pp. 487-509 ◽  
Author(s):  
S. J. Burns ◽  
S. P. Burns
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Negative Thermal Expansion ◽  
Mechanical Work ◽  
Interatomic Potentials ◽  
P Waves ◽  
Thermal Expansion Coefficients ◽  
The Earth ◽  
Expansion Coefficients

Abstract. The thermal expansion coefficient is presented as the coupling between heat energy and mechanical work. It is shown that when heat and work are uncoupled then very unusual material properties occurs: for example, acoustic p waves are not damped and heat is not generated from mechanical motion. It is found that at pressures defined by the bulk modulus divided by the Anderson–Grüneisen parameter, then the thermal expansion coefficient approaches zero in linear-elastic models. Very large pressures always reduce thermal expansion coefficients; the importance of a very small or even negative thermal expansion coefficient is discussed in relation to physical processes deep in the core and mantle of Earth. Models of the thermal expansion coefficients based on interatomic potentials which are always relegated to isometric conditions preclude any changes in volume due to temperature changes. However, it is known that the pressures in the Earth are large enough to effectively reduce thermal expansion coefficients to near zero which decouples heat from mechanical work.

On the suitability of the volume-averaging approximation for the description of thermal expansion coefficient of nanofluids

2014 ◽  
Vol 229 (15) ◽  
pp. 2835-2841 ◽  
Author(s):  
Iman Zahmatkesh
Keyword(s):  
Thermal Expansion ◽  
Natural Convection ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Averaging ◽  
Thermal Fields ◽  
Current Contribution ◽  
Water Based ◽  
Expansion Coefficients ◽  
Porous Enclosure

Currently, volume-averaging approximation is in common use for the description of thermal expansion coefficient of nanofluids in terms of expansion coefficients of their constituents. The accuracy of this method is not, however, so clear since it ignores the dependence of density on temperature in the prediction of thermal expansion coefficient that may not be true in natural convection circumstances. In the current contribution, attention is focused to clarify how predictions of flow and thermal fields as well as heat transfer and entropy generation characteristics during natural convection of nanofluids may be influenced if one adopts the volume-averaging approximation for the description of thermal expansion coefficient. For this purpose, a porous enclosure saturated with several water-based nanofluids is simulated and results of the volume-averaged thermal expansion coefficient are compared with those of a recent correlation that takes into account the dependence of density on temperature.

scholarly journals Theoretical Investigation of Thermal Expansion Coefficients of SiC Reinforced Copper Matrix Composites

2020 ◽  
Vol 2 (2) ◽  
pp. 22
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Theoretical Investigation ◽  
Pure Copper ◽  
Copper Matrix ◽  
Electronics Industry ◽  
Matrix Composites ◽  
Thermal Expansion Coefficients ◽  
Turner Model ◽  
Expansion Coefficients

The thermal expansion coefficient (CTE) of the copper element, which is widely used in the electronics industry, is quite high. It is of great importance to decrease the CTE value in order not to deform against the heat it is exposed to. In this study, it is aimed to theoretically examine the changes in CTE value when SiC supplement is applied to pure copper. For this purpose, CTE value calculations were made according to Kerner and Turner's models for composites that were reinforced at different rates by volume. Sample studies in the literature have been utilized for percent component ratios. In this context, the amount of reinforcement was adjusted to be 5, 10, 15, and 20vol.% by volume. According to the findings, it was observed that there was ̴ %4-17 decrease in CTE value based on the Kerner model and ̴ %7-26 decrease based on the Turner model.

The Alloy Design of Metallic Interconnector of Solid Oxide Electrolyte Fuel Cell (SOFC)

2007 ◽  
Vol 561-565 ◽  
pp. 1617-1620
Author(s):  
Ian Bo Chen ◽  
Shuang Shii Lian ◽  
Chia Ying Li ◽  
Wei Ja Shong ◽  
Ruey Yi Lee
Keyword(s):  
Thermal Expansion ◽  
Fuel Cell ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Low Cost ◽  
Melting Furnace ◽  
Solid Oxide ◽  
Temperature Oxidation ◽  
Thermal Expansion Coefficients ◽  
Metallic Interconnector

This study is intended to reduce the difference of thermal expansion coefficient between metallic interconnector and solid electrolyte of SOFC (Solid Oxide Fuel Cell) without sacrificing of electrical conductivity. Fe-Cr alloys have been chosen as candidate materials due to its merit of low cost and high temperature oxidation resistance. Different amount of alloys element and compositions have been varied to optimize the properties by method of alloys design with aid of thermodynamics software Thermal-Cal. Phase diagrams of multi-components alloys have been drawn to predict the possible stable phases formed in the investigated metals. An arc melter and plasma melting furnace were used to melt the investigated alloys. The measurements of thermal expansion coefficients and electrical conductivities are carried out with TMA and ASR resistance instrument. The results indicate that the Fe-10Cr alloy exhibits the smallest thermal expansion coefficient among the alloys, while Fe-16Cr has a lowest electrical resistance .

New Ti-Alloy with Negative and Zero Thermal Expansion Coefficients

2011 ◽  
Vol 495 ◽  
pp. 62-66 ◽  
Author(s):  
Mohamed Abdel Hady Gepreel
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
Cold Deformation ◽  
Negative Thermal Expansion ◽  
Expansion Factor ◽  
Thermal Expansion Coefficients ◽  
Ti Alloys ◽  
History Of

Most materials expand upon heating due to the anharmonicity of the atomic potential energy. This thermal expansion is one of the intrinsic properties of any material which is very difficult to be controlled. Recently, a negative thermal expansion factor was introduced to those Ti-alloys with high elastic softening when cold deformed. This negative thermal expansion factor is changeable in these types of alloys depending on the alloy composition, degree of cold deformation, and thermal history of the alloy. This change gives a lot of room to control the coefficient of thermal expansion (CTE) of those Ti-alloys to turn from positive though zero to negative values and vice versa. In this paper, the appearance of the NTE factor is discussed and the possible methods to control the final thermal expansion coefficient to achieve a zero thermal expansion coefficient are presented. The unique thermal expansion behavior of the alloys will locate them as an excellent candidate in sensing apparatus and other precious equipments.

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