scholarly journals Investigation of the thermophysical characteristics of triticale grain of the Gorka variety by the method of non-stationary thermal re-gime

2021 ◽  
Vol 83 (2) ◽  
pp. 17-22
Author(s):  
A. V. Drannikov ◽  
T. N. Tertychnaya ◽  
A. A. Shevtsov ◽  
N. V. Zasypkin ◽  
A. A. Ryndin
Keyword(s):  
Thermal Conductivity ◽  
Thermal Characteristics ◽  
Essential Amino Acids ◽  
Thermophysical Characteristics ◽  
New Variety ◽  
Grain Crop ◽  
Temperature Time ◽  
Micro Elements ◽  
Measuring Unit

In solving the problem of vegetable protein deficiency, triticale grain is of great interest – a unique hybrid that com-bines the best hereditary qualities of wheat and rye. The protein content of triticale is 1.0 – 1.5% higher than that of wheat and 3–4% higher than that of rye. Obtained a new variety of grain triticale – "Slide". Products prepared from this grain crop have a high nutritional value, since the protein that is part of triticale is characterized by an increased content of essential amino acids, and is not inferior to wheat grain in terms of the content of macro – and micro-elements. It contains a lot of copper, phosphorus, potassium, magnesium, calcium, sodium, zinc, manganese and iron, as well as vitamins В9, В5, В1, PP and E. Information about thermal characteristics as functions of tempera-ture plays a key role in engineering calculations and mathematical modeling of the processes of drying and heat treatment of triticale grain. The method of nonstationary thermal regime, based on the solution of the problem of thermal conductivity over two temperature-time points, developed by B.C. Wolkenstein, was used to determine the thermophysical characteristics. The determination of the thermophysical characteristics of the grain was carried out on the Kossfield RT 1394 N measuring unit (National Instruments). Revealed the character of the dependence of diffusivity, thermal conductivity and specific heat capacity on temperature. Equations describing the thermophysi-cal characteristics of grain at a humidity of 13.57 and 21.83% in the temperature range of 20–100 оС are obtained

scholarly journals Thermal Conducting Properties of Metal-fluoroplastic Material Determined by Tribological Method

2021 ◽  
pp. 378-384
Author(s):  
Vasily N. Kornopoltsev ◽  
Bair B. Damdinov
Keyword(s):  
Thermal Conductivity ◽  
Sheet Metal ◽  
Thermal Conductivity Coefficient ◽  
Steel Substrate ◽  
Approximate Determination ◽  
Fourier Law ◽  
Thermophysical Characteristics ◽  
Friction Zone ◽  
Thermal Conducting

The work is devoted to considering the possibility of using the Fourier law and the data of tribological tests for the approximate determination of the thermophysical characteristics of the sheet metal-fluoroplastic material on a steel substrate. The thermal conductivity coefficient of two different fluoroplastic materials was determined by tribological method using the temperature difference in the friction zone. It was shown that friction conditions change from viscoelastic to plastic

scholarly journals CHARACTERIZATION OF HEAT CONDUCTIVITY OF ECCENTRICALLY ROTATING HEAT PIPES USED FOR COOLING OF MOTOR SPINDLES

2021 ◽  
Vol 2021 (3) ◽  
pp. 4698-4705
Author(s):  
B. Denkena ◽  
◽  
B. Bergmann ◽  
K. Kono ◽  
R. Ishiguro ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Heat Exchangers ◽  
Thermal Characteristics ◽  
Heat Pipes ◽  
Simulation Based ◽  
Wick Structure ◽  
Parameter Values

Heat losses within motor spindles lead to undesired effects such as machining inaccuracies and de-creasing lifetime of the motor and bearings. To reduce thermal loads, complex shaft cooling concepts with costly sealing techniques exist. For this reason, a novel, less costly cooling concept has been de-veloped based on heat pipes with high thermal conductivity and fin-shaped heat exchangers. The de-sign and integration of these heat exchanger elements into a motor spindle is carried out using the fi-nite element method. The aim is to optimize the efficiency of the heat pipes and heat exchangers for optimal shaft cooling performance. For a simulation-based development of a prototype spindle, un-known thermal characteristics of the heat transfer elements must be determined. In this paper, the de-termination of the thermal conductivity of the heat pipes is described. The determination of conductivi-ty is done experimentally. First, the developed test rig and the applied procedure for the determination of the conductivity are shown. Subsequently, the experimental results are presented and discussed. Two types of heat pipes were analyzed: Copper heat pipes with sintered wick structure and nickel-plated copper heat pipes with axial grooves. The influences of rotational speed, heat flow rates and the angle between the heat pipe and main axis of rotation were investigated. The results indicate a distinct dependency of the conductivity on the varied parameters. However, changes of parameter values have very different quantitative and qualitative effects on the determined conductivities de-pending on the type of heat pipe.

Research on thermophysical characteristics of food products

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Z. A. Burova ◽  
◽  
S.O. Ivanov ◽  
T.O. Roman ◽  
V. P. Vasyliv ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Thermal Effects ◽  
Food Products ◽  
Thermophysical Characteristics ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Wide Range

Healthy diet is one of the most important elements in maintaining health and strengthening the nation's immunity, an essential condition for achieving active longevity of present and future generations. Inventing new ingredients and creation of food products based on them, development of new and improvement of existing technologies requires reliable information about the basic thermophysical characteristics of raw materials and biological substances to calculate and optimize heat and mass transfer processes during processing and production. Modern science offers a wide range of studies on the thermodynamic and heat and mass transfer process parameters, determination of the thermophysical characteristics of new substances and products using metrologically certified devices and information measuring systems. The main problem in the study of materials of biological origin is their inhomogeneity and sample structure heterogeneity. Measuring the effective thermal conductivity coefficient of bulk materials and cereals should be carried out in a stationary thermal mode on the device for determination of the thermophysical properties of materials and thermal effects, which implements a symmetrical scheme of the thermometric method of measurement using heat flow and temperature sensors. Using four measuring cells allows synchronous comparative analysis of several samples, and the rotary clamping mechanism helps to minimize contact resistance. The developed technique for measuring the coefficient of effective thermal conductivity takes into account the characteristics of bulk food products and significantly increases the accuracy of their thermal conductivity determination by introducing a correction for the contact resistance of the wall layer. The possibility of long-term observations allows to study thermolabile materials, analyze the thermal effects in the samples, to estimate the volumetric and integral heat dissipation. Calorimetric studies of a wide range of biological materials and substances can be performed with sufficient accuracy by the STA system, which implements step-by-step scanning and synchronous thermal analysis methods to determine the specific heat capacity and heat of evaporation, the ratio of free and bound moisture in heterogeneous materials. These characteristics are integral parameters in the study of the kinetics of heat and mass transfer processes, including drying, for the calculation and design of process equipment. Research on the thermophysical characteristics of heterogeneous materials and substances will optimize production processes and further develop technologies in the food, biotechnology, and processing industries.

scholarly journals The Use of Complete Temperature?Time Curves for Determination of Thermal Conductivity with Particular Reference to Rocks

1959 ◽  
Vol 12 (3) ◽  
pp. 203 ◽  
Author(s):  
JC Jaeger
Keyword(s):  
Thermal Conductivity ◽  
Time Curve ◽  
Transient Methods ◽  
Temperature Time

Most of the transient methods at present in use for the determination of thermal conductivity involve the study of the asymptote of a temperature-time curve. This implies that they require relatively long times of experiment and make no use of the information contained in measurements of temperature at smaller times.

Теплофизические характеристики теплозащитного материала корпуса ракетного двигателя при температурах до 1000 оС

2021 ◽  
pp. 11-18
Author(s):  
Геннадий Александрович Фролов ◽  
Юрий Игоревич Евдокименко ◽  
Вячеслав Михайлович Кисель ◽  
Ирина Александровна Гусарова
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Temperature Fields ◽  
Thermophysical Characteristics ◽  
Furnace Heating ◽  
Temperature Dependences ◽  
Good Agreement

An experimental determination of the temperature dependences of the specific heat capacity and the thermal conductivity coefficient of the multifunctional coating MFP-92 at temperatures up to 1000 °C has been carried out. At temperatures up to 450 °C, an IT-c-400 device was used to determine the specific heat capacity. IT-l-400 device was used for the determination of thermal conductivity. At higher temperatures, the determination of the thermophysical characteristics (TPC) was carried out by solving the inverse problem of thermal conductivity (IPT) in a flat plate under conditions of one-sided heating in a muffle furnace. Composite material MFP-92 is a multilayer structure with upper layers based on silica fabric and chromophosphate binder and lower layers based on mullite-silica fabric and aluminosilicate binder. The TPC of the layers also differ from each other, and, accordingly, the properties of this material as a whole can be determined only in the form of their effective values, averaged in one way or another over the thickness of the coating. In addition, during heating, the material undergoes significant physicochemical transformations associated with the thermal destruction of its components, manifested in the form of abundant gas release, and a decrease in the density of the material, which significantly changes its TPC and determines its dependence on the heating rate. Therefore, studies of the thermophysical characteristics of the MFP-92 material were carried out with several (2-5) consecutive heating cycles. It was found that in four heating cycles of the MFP-92 material up to 450 °C for 75 minutes when measuring the specific heat on the IT-c-400 device, its temperature dependence significantly changes qualitatively and quantitatively. With furnace heating to 1000 °C, the temperature dependences of the TPC of the material, determined in the first and second heating cycles, have a different form, but change insignificantly in subsequent heating cycles. This makes it possible to ascribe to the MFP-92 material a set of two sets of TPC related to its initial (phase A) and annealed after heating to 1000 °C (phase B) states. Using the obtained TPС of phase A (including the magnitude of the thermal effect of irreversible endothermic phase transition at 100 °C) and phase B, good agreement was obtained between the calculated and experimental temperature fields in the samples under furnace heating conditions.

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