scholarly journals A Robust Miniaturized Gas Sensor for H2 and CO2 Detection Based on the 3ω Method

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 485
Author(s):  
Dominik Berndt ◽  
Josef Muggli ◽  
Robert Heckel ◽  
Mohd Fuad Rahiman ◽  
Matthias Lindner ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Excitation Frequency ◽  
Thermal Characterization ◽  
Accurate Method ◽  
Gas Analysis ◽  
Measurement Technology ◽  
Sensing Element ◽  
3Ω Method ◽  
Vacuum Measurement

Gas concentration monitoring is essential in industrial or life science areas in order to address safety-relevant or process-related questions. Many of the sensors used in this context are based on the principle of thermal conductivity. The 3ω-method is a very accurate method to determine the thermal properties of materials. It has its origin in the thermal characterization of thin solid films. To date, there have been very few scientific investigations using this method to determine the thermal properties of gases and to apply it to gas measurement technology. In this article, we use two exemplary gases (H2 and CO2) for a systematical investigation of this method in the context of gas analysis. To perform our experiments, we use a robust, reliable sensing element that is already well established in vacuum measurement technology. This helix-shaped thin wire of tungsten exhibits high robustness against chemical and mechanical influences. Our setup features a compact measurement environment, where sensor operation and data acquisition are integrated into a single device. The experimental results show a good agreement with a simplified analytical model and FEM simulations. The sensor exhibits a lower detection limit of 0.62% in the case of CO2, and only 0.062% in case the of H2 at an excitation frequency of 1Hz. This is one of the lowest values reported in literature for thermal conductivity H2 sensors.

A Phase-Sensitive Technique for the Thermal Characterization of Dielectric Thin Films

1999 ◽  
Vol 121 (3) ◽  
pp. 528-536 ◽  
Author(s):  
S. W. Indermuehle ◽  
R. B. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Temperature Response ◽  
Front Surface ◽  
Thermal Characterization ◽  
Fused Silica ◽  
Dielectric Thin Films ◽  
Phase Sensitive

A phase-sensitive measurement technique for determining two independent thermal properties of a thin dielectric film is presented. The technique involves measuring a specimen’s front surface temperature response to a periodic heating signal over a range of frequencies. The phase shift of the temperature response is fit to an analytical model using thermal diffusivity and effusivity as fitting parameters, from which the thermal conductivity and specific heat can be calculated. The method has been applied to 1.72-μm thick films of SiO2 thermally grown on a silicon substrate. Thermal properties were obtained through a temperature range from 25°C to 300°C. One interesting outcome stemming from analysis of the experimental data is the ability to extract both thermal conductivity and specific heat of a thin film from phase information alone. The properties obtained with this method are slightly below the bulk values for fused silica with a measured room temperature (25°C) thermal conductivity of 1.28 ± 0.12 W/m-K.

scholarly journals Thermal Characterization of Phantoms Used for Quality Assurance of Deep Hyperthermia Systems

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4549
Author(s):  
Laura Farina ◽  
Kemal Sumser ◽  
Gerard van Rhoon ◽  
Sergio Curto
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Characterization ◽  
Sensitivity Study ◽  
Volumetric Heat Capacity ◽  
Internal Organs ◽  
Protocol Optimization ◽  
Thermal Measurements ◽  
Deep Hyperthermia

Tissue mimicking phantoms are frequently used in hyperthermia applications for device and protocol optimization. Unfortunately, a commonly experienced limitation is that their precise thermal properties are not available. Therefore, in this study, the thermal properties of three currently used QA phantoms for deep hyperthermia are measured with an “off-shelf” commercial thermal property analyzer. We have measured averaged values of thermal conductivity (k = 0.59 ± 0.07 Wm−1K−1), volumetric heat capacity (C = 3.85 ± 0.45 MJm−3K−1) and thermal diffusivity (D = 0.16 ± 0.02 mm2s−1). These values are comparable with reported values of internal organs, such as liver, kidney and muscle. In addition, a sensitivity study of the performance of the commercial sensor is conducted. To ensure correct thermal measurements, the sample under test should entirely cover the length of the sensor, and a minimum of 4 mm of material parallel to the sensor in all directions should be guaranteed.

Thermal Characterization of Polymer Composites by Using the 3-Omega Method

2013 ◽  
Author(s):  
Dong-Wook Oh ◽  
Young Kim ◽  
Jun Seok Choi ◽  
Ook Joong Kim ◽  
Kong Hoon Lee
Keyword(s):  
Thermal Conductivity ◽  
Polymer Composites ◽  
Thermal Characterization ◽  
Mechanical And Thermal Properties ◽  
Additive Concentration ◽  
3Ω Method ◽  
Omega Method ◽  
3 Omega ◽  
Property Measurement

Polymer composites having comparable thermal conductivity to stainless steel at room temperature are commercially available nowadays. Metal or carbon fiber and particles are added to base polymers to enhance mechanical and thermal performance. However for polymer composites having high additive concentration, characterizing mechanical and thermal properties of the composite may be a challenging problem due to an-isotropic natural and non-homogeneity. In this paper, a novel thermal property measurement method based on the 3-omega (3ω) is proposed for thermal analysis of polymer composites. Sensitivity and feasible limit of the 3ω method with “boundary mismatch assumption” is analyzed for measurement of polymer composites having broad range of thermal conductivity.

3D Examination of the Thermal Properties of Carbon-Carbon Composites

2014 ◽  
Author(s):  
Melanie Patrick ◽  
Messiha Saad
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
High Temperature ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermal Characterization ◽  
Flash Method ◽  
Carbon Composites ◽  
Scanning Calorimetry ◽  
Temperature Levels

Thermal characterization of composites is essential for their proper assignment to a specific application. Specific heat, thermal diffusivity, and thermal conductivity of carbon-carbon composites are essential in the engineering design process and in the analysis of aerospace vehicles, space systems and other high temperature thermal systems. Specifically, thermal conductivity determines the working temperature levels of a material and is influential in its performance in high temperature applications. There is insufficient thermal property data for carbon-carbon composites over a range of temperatures. The purpose of this research is to develop a thermal properties database for carbon-carbon composites that will contain in-plane (i-p) and through-the-thickness (t-t-t) thermal data at different temperatures as well as display the effects of graphitization on the composite material. The carbon-carbon composites tested were fabricated by the Resin Transfer Molding (RTM) technique, utilizing T300 2-D carbon fabric and Primaset PT-30 cyanate ester resin. Experimental methods were employed to measure the thermal properties. Following the ASTM standard E-1461, the flash method enabled the direct measurement of thermal diffusivity. Additionally, differential scanning calorimetry was performed in accordance with the ASTM E-1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density data were used to compute the thermal conductivity of the carbon-carbon composites. The measured through-the-thickness thermal conductivity values of all the materials tested range from 1.0 to 17 W/m·K, while in-plane values range from 3.8 to 4.6 W/m·K due to the effect of fiber orientation. Additionally, the graphitized samples exhibit a higher thermal conductivity because of the nature of the ordered graphite structure.

scholarly journals Effect of Sunflower, Almond, and Rapeseed Oils as Additives on Thermal Properties of a Machinery Oil

2021 ◽  
Vol 11 (16) ◽  
pp. 7441
Author(s):  
José de Jesús Agustín Flores Cuautle ◽  
Oscar Osvaldo Sandoval González ◽  
Carlos Omar González Morán ◽  
José Pastor Rodríguez Jarquin ◽  
Citlalli Jessica Trujillo Romero ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Vegetable Oils ◽  
Thermal Effusivity ◽  
Thermal Characterization ◽  
Tocopherol Content ◽  
Lubricating Oil ◽  
Wave Resonance ◽  
Resonance Cavity

Vegetable oils are considered to be eco-friendly and to offer good lubricant properties; however, their low thermo-oxidative stability makes their use as a lubricant base challenging. In this research, sunflower, almond, and rapeseed vegetable oils were added in volumes of 5, 10, 15, and 20% to a machinery oil, and the thermal properties of the resulting fluids were studied. Sunflower, almond, and rapeseed oils were chosen considering their fatty acid composition and the tocopherol content. During this investigation, thermal diffusivity was measured by using the thermal wave resonance cavity technique, while thermal effusivity was determined by the inverse photopyroelectric method, and the obtained values ranged from 4.63 to 5.75 Ws1/2m−2K−1 × 102. The thermal conductivity was calculated by obtaining a complete thermal characterization. The results showed a linear relationship between the percentage of vegetable oil and the thermal diffusivity. It was also noted that the thermal properties of diffusivity and effusivity could be tuned when using almond, sunflower, and rapeseed oils in the appropriate percentages. Hence, the influence of vegetable oils on the thermal properties of lubricating oil were closely related to the number of fatty acids.

scholarly journals Production and Thermal Characterization of Ethanol Blends from Black Jaggery

2020 ◽  
Vol 8 (6) ◽  
pp. 5398-5401
Keyword(s):  
Thermal Conductivity ◽  
Global Warming ◽  
Thermal Properties ◽  
Fossil Fuels ◽  
Fossil Fuel ◽  
Thermal Characterization ◽  
Thermal Constant ◽  
Ethanol Blends ◽  
Alternate Fuels

To protect the environment from the global warming dependency on the fossil fuels have to be reduced. Locally available alternate fuels are greatly prominent for the development of industrialization compared to conventional fuels. This paper mainly deals with the production of Ethanol from a source called “Black Jaggery” and an Optimization of the extracted alcohol to attain the characteristics and properties which would be essential to blend the alcohol with an existing fossil fuel. Black Jaggery being a sugar-based product is fermented in the presence of a yeast enzyme for several days and is distilled to extract the bio-fuel (ethanol) from the source. The extracted oil is characterized for the thermal properties by using thermal constant analyzer TPS-500 which will be helpful for the combustion studies. Obtained results shows that compared to E-5, E-10 and E-20, E-15 blend shows better thermal properties increased thermal conductivity, thermal diffusivity with reduced specific heat.

Thermal Conductivity of Carbon Nanotube Aerogels With Different Filling Gases

2012 ◽  
Author(s):  
Scott N. Schiffres ◽  
Kyu Hun Kim ◽  
Youngseok Oh ◽  
Mohammad F. Islam ◽  
Jonathan A. Malen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Effusivity ◽  
Phonon Transport ◽  
Single Walled Carbon Nanotube ◽  
3Ω Method ◽  
Vacuum Measurement ◽  
Mechanical And Electrical Properties ◽  
Thermal Interface Resistance ◽  
Different Gases

We report on measurements of thermal conductivity in single-walled carbon nanotube (SWCNT) aerogels in vacuum, and as infiltrated by different gases. The remarkable thermal, mechanical and electrical properties of single CNTs have led to great interest in bulk carbon nanotube materials, including the CNT aerogels. Carbon nanotube aerogels are light-weight (7–8kg/m3) and porous, which means that heat will be conducted in parallel through the SWCNT matrix and the filling gas. The overall thermal conductivity of the aerogel was measured with helium, and argon filling gases, using a modified 3ω method designed to interrogate low thermal effusivity materials. Measurements of thermal conductivity at vacuum are 0.023 W/m-K and at atmospheric pressure infiltrated SWCNT aerogels have thermal conductivities in helium of 0.19 W/m-K and in argon of 0.039 W/m-K. Our vacuum measurement suggests that transport within the aerogel is limited by the thermal interface resistance between SWCNTs, rather than by phonon transport within the SWCNT itself. We have also extracted the mean distance traveled by gas molecules between collisions with SWCNT aerogel by fitting the gas contribution to thermal conductivity using a kinetic theory based model.

Mechanical and thermal characterization of grafted PP-NCC nanocomposites

2019 ◽  
pp. 089270571987822
Author(s):  
Saud Aldajah ◽  
Mohammad Y Al-Haik ◽  
Waseem Siddique ◽  
Mohammad M Kabir ◽  
Yousef Haik
Keyword(s):  
Thermal Properties ◽  
Interfacial Adhesion ◽  
Thermal Characterization ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Three Point Bending ◽  
Twin Screw ◽  
Thermal Stability Of

This study reveals the enhancement of mechanical and thermal properties of maleic anhydride-grafted polypropylene (PP- g-MA) with the addition of nanocrystalline cellulose (NCC). A nanocomposite was manufactured by blending various percentages of PP, MA, and NCC nanoparticles by means of a twin-screw extruder. The influence of varying the percentages of NCC on the mechanical and thermal behavior of the nanocomposite was studied by performing three-point bending, nanoindentation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy tests. The novelty of this study stems on the NCC nanoparticles and their ability to enhance the mechanical and thermal properties of PP. Three-point bending and nanoindentation tests revealed improvement in the mechanical properties in terms of strength, modulus, and hardness of the PP- g-MA nanocomposites as the addition of NCC increased. SEM showed homogeneity between the mixtures which proved the presence of interfacial adhesion between the PP- g-MA incorporated with NCC nanoparticles that was confirmed by the FTIR results. DSC and TGA measurements showed that the thermal stability of the nanocomposites was not compromised due to the addition of the coupling agent and reinforced nanoparticles.

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

scholarly journals Testing a Gypsum Composite Based on Raw Gypsum with a Direct Admixture of Paraffin and Polymer to Improve Thermal Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3241
Author(s):  
Krzysztof Powała ◽  
Andrzej Obraniak ◽  
Dariusz Heim
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Phase Change ◽  
Large Scale ◽  
Building Materials ◽  
Residential Buildings ◽  
Energy Performance ◽  
Polymer Content ◽  
Volumetric Heat Capacity

The implemented new legal regulations regarding thermal comfort, the energy performance of residential buildings, and proecological requirements require the design of new building materials, the use of which will improve the thermal efficiency of newly built and renovated buildings. Therefore, many companies producing building materials strive to improve the properties of their products by reducing the weight of the materials, increasing their mechanical properties, and improving their insulating properties. Currently, there are solutions in phase-change materials (PCM) production technology, such as microencapsulation, but its application on a large scale is extremely costly. This paper presents a solution to the abovementioned problem through the creation and testing of a composite, i.e., a new mixture of gypsum, paraffin, and polymer, which can be used in the production of plasterboard. The presented solution uses a material (PCM) which improves the thermal properties of the composite by taking advantage of the phase-change phenomenon. The study analyzes the influence of polymer content in the total mass of a composite in relation to its thermal conductivity, volumetric heat capacity, and diffusivity. Based on the results contained in this article, the best solution appears to be a mixture with 0.1% polymer content. It is definitely visible in the tests which use drying, hardening time, and paraffin absorption. It differs slightly from the best result in the thermal conductivity test, while it is comparable in terms of volumetric heat capacity and differs slightly from the best result in the thermal diffusivity test.

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