scholarly journals Thermal Diffusivity of Linear Alkanes and its Behaviour with the Size of the Chain: Study with a Photopyroelectric Technique

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Property ◽  
Heat Transport ◽  
Spatial Configuration ◽  
Molecular Size ◽  
Photopyroelectric Technique ◽  
Molecular Configuration ◽  
Science And Engineering ◽  
Linear Alkanes ◽  
Nonstationary Conditions

Thermal transport properties of substances are fundamental for science and engineering. Among these properties, thermal diffusivity characterizes the way materials transport heat under nonstationary conditions. The manner in which this thermal property behaves with the size or molecular configuration is very important to understand the mechanisms involved in heat transport. It is a complicated work to study variations on this thermal property taking these two variables (size and configuration) together. Linear alkanes have essentially the same spatial configuration, varying only the molecular size (the number of involved carbon atoms in the molecule), so they are ideal substances to study the behaviour of thermal properties with the molecular size alone. In this work photopyroelectric technique, taking the sample´s thickness as variable (the so-called TWRC method), is used for thermal diffusivity measurements of linear alkanes, from 1-heptane to 1-heptadecane. It is shown that this thermal property increases with the molecular size. This behaviour can be explained in a very simple way if it is considered that the increase in molecular size increases “routes” of heat transport.

scholarly journals Effect of the pitch particle size on the thermal property of carbon foams

2021 ◽  
Vol 631 (1) ◽  
pp. 012072
Author(s):  
Jing Xia ◽  
Junqing Liu ◽  
Wenbin Liang
Keyword(s):  
Particle Size ◽  
Thermal Diffusivity ◽  
Thermal Property ◽  
Carbon Foam ◽  
Carbon Foams ◽  
Degree Of Graphitization

Abstract In this research, the influence of the pitch particle size on the thermal diffusivity of the carbon foam was studied. The results indicate that the thermal diffusivity increases from 12.3 mm2/s to 23.09 mm2/s with an increasing pitch particle size from <500 mesh to 100-200 mesh, because the carbon foam produced by using larger pitch particle has highly aligned graphitic structures with less cracks and folded texture and its degree of graphitization is higher.

Photothermal methods for determination of thermal properties of bulk materials and thin films

Open Physics ◽  
2010 ◽  
Vol 8 (2) ◽  
Author(s):  
Jerzy Bodzenta ◽  
Anna Kaźmierczak-Bałata ◽  
Jacek Mazur
Keyword(s):  
Thin Films ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Heat Transport ◽  
Temperature Fields ◽  
Nonstationary Temperature ◽  
Measuring Techniques ◽  
Heat Transport Properties ◽  
Photothermal Methods

AbstractInformation on the thermal properties of materials is very important both in fundamental physical research and in engineering applications. The development of materials with desirable heat transport properties requires methods for their experimental determination. In this paper basic concepts of the measurement of parameters describing the heat transport in solids are discussed. Attention is paid to methods utilizing nonstationary temperature fields, especially to photothermal methods in which the temperature disturbance in the investigated sample is generated through light absorption. Exemplary photothermal measuring techniques, which can be realized using common experimental equipment, are described in detail. It is shown that using these techniques it is possible to determine the thermal diffusivity of bulk transparent samples, opaque and semi-transparent plate-form samples, and the thermal conductivity of thin films deposited on thick substrates. Results of the investigation of thermal diffusivity of the ground in the polar region, which is based on the analysis of the propagation of the thermal wave generated by sun-light, are also presented. Based on chosen examples one can state that photothermal techniques can be used for determination of the thermal properties of very different materials.

Heat transport in epoxy and polyester carbonyl iron microcomposites: The effect of concentration and temperature

2017 ◽  
Vol 52 (10) ◽  
pp. 1331-1338
Author(s):  
NW Pech-May ◽  
C Vales-Pinzon ◽  
A Vega-Flick ◽  
A Oleaga ◽  
A Salazar ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Carbonyl Iron ◽  
Numerical Differentiation ◽  
Photopyroelectric Technique ◽  
Iron Particles ◽  
High Concentration ◽  
Polyester Resins ◽  
Wide Range ◽  
Study Heat Transfer

Temperature dependence of the thermal diffusivity in composites of epoxy and polyester resins, loaded with carbonyl iron particles, has been studied using the photopyroelectric technique. Increments of eight and 2.5 times the thermal conductivity of the polymers are obtained, as the volume concentration of microparticles is increased from 0% to 40% for epoxy and from 0% to 20% for polyester matrices, respectively. Additionally, the thermal diffusivity falls systematically as the temperature is increased from 270 to 400 K; the effect is more pronounced for high concentration of microparticles in epoxy composites. The glass transition of the composites is explored by implementing a numerical differentiation algorithm. In order to explain the consequences of the loading of the composites on the thermal conductivity, a modified Lewis-Nielsen model, which includes the presence of crowded regions in the samples, is used to study heat transfer in a wide range of particle concentrations.

Transient Plane Source Method for Thermal Property Measurements of Metal Hydrides

2008 ◽  
Author(s):  
Scott Flueckiger ◽  
Yuan Zheng ◽  
Timothe´e Pourpoint
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Diffusivity ◽  
Hydrogen Storage ◽  
Thermal Property ◽  
Metal Hydride ◽  
Metal Hydrides ◽  
Flash Method ◽  
Plane Source ◽  
Transient Plane Source

Metal hydrides are promising hydrogen storage materials with potential for practical use in a passenger car. To be a viable hydrogen storage option, metal hydride heat transfer behavior must be well understood and accounted for. As such, the thermal properties of the metal hydride are measured and compiled to assess this behavior. These properties include thermal conductivity, specific heat, and thermal diffusivity. The transient plane source (TPS) method was selected primarily due to a high level of versatility, including customization for high pressure hydrogen environments. To perform this measurement, a TPS 2500 S thermal property analyzer by the Hot Disk Company was employed. To understand the measurement and analysis process of the TPS method, two different sample materials were evaluated at ambient conditions. These samples included a stainless steel pellet and an inactivated (non-pyrophoric) metal hydride pellet. Thermal conductivity and thermal diffusivity of these samples were measured using the TPS method. The thermal property measurements are compared to the data available in the literature (stainless steel) and the data obtained using laser flash method (metal hydride). The improvements needed to successfully implement the TPS method are discussed in detail.

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