scholarly journals Expansion of the Range of Refrigeration of the Surface Heat Flow Unit Under Conductive Energy Produce

2018 ◽  
pp. 27-32
Author(s):  
S. Kovtun
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Flux Density ◽  
Heat Flux Density ◽  
Dynamic Range ◽  
Density Measurement ◽  
Lower Boundary ◽  
Surface Heat ◽  
Total Uncertainty ◽  
Unit Of Measurement

The article presents the results of investigations of factors that influence the accuracy of reproduction of the unit of measurement of the surface density of the heat flow by conductivity. Components of the uncertainty of the surface heat flux density measurement were analyzed using the Ishikawa cause-and-effect diagram, as shown in Fig. 1 The mathematical model of the method of reproduction of the unit of measurement was obtained, which takes into account the influence of the sources of uncertainty by making the corresponding corrections. The possibility of extending the lower boundary of the dynamic range by the correction of the factors having the greatest influence is substantiated. The rationale is based on the estimation of the uncertainty of the individual components, which, in the course of the correction of their impact, should not exceed the values (achieved to date). As an example, the calculation of the total uncertainty in the reproduction of the heat flux density of 20 W·m-2 is given. Table 1 contains all data important for the uncertainty analysis such as input quantities, their estimated values as well as the associated sensitivity coefficients and the variances determined.

scholarly journals The surface heat flux density of a bare soil

1983 ◽  
Vol 21 (4) ◽  
pp. 431-443 ◽  
Author(s):  
M.D. Novak ◽  
T.A. Black
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Bare Soil ◽  
Surface Heat

Surface heat transfer coefficient measurement by immersed temperature sensor and inverse modelling

2016 ◽  
Vol 83 (11) ◽  
Author(s):  
Mirko Javurek ◽  
Andreas Mittermair
Keyword(s):  
Heat Flux ◽  
Inverse Problem ◽  
Flux Density ◽  
Temperature Sensor ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Surface Heat ◽  
Problem Solution ◽  
Inverse Problem Solution

AbstractA transient surface heating or cooling process of a solid is considered. A procedure for the determination of surface temperature and surface heat flux density during such a process is presented using a submersed temperature sensor in the solid. From this measured temperature the surface temperature and surface heat flux density are calculated by inverse process modelling. This method is prone to errors since measurement errors are amplified in the inverse process modelling and can thus easily become unacceptably large. The LSQR regularisation algorithm is optimised for fast performance as well as less memory requirement and applied to the inverse problem solution. The proposed method allows to simulate an experimental setup and to determine the accuracy of the results gained from the simulated experiment. This is essential for the determination of the accuracy of a planned or existing test facility. The influence of process parameters like sensor depth, sensor noise level, sampling rate, heat flux density amplitude and cooling/heating process duration is investigated. In most cases it is very important to carefully adjust the process parameters in order to obtain reliable and accurate results. Additionally the proper selection of the regularisation parameter required for the inverse problem solution is analysed.

The Probability Distribution Modeling of Surface Heat Flux Density on Metal Material

2013 ◽  
Vol 738 ◽  
pp. 42-45
Author(s):  
Cheng Zhi Yang ◽  
Li Zhou
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
Flux Density ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
New Technology ◽  
Surface Heat ◽  
Heating Process ◽  
Metal Material ◽  
Flux Density Distribution

In order to get the energy consumption relationship in the heating process of metal material, the probability and statistics law between the temperature distribution and surface heat flux density of heating metal material is established in this paper. Moreover the surface heat flux density distribution of heating metal material is used to associate with its energy consumption. And it builds a new technology method for saving energy control decisions.

scholarly journals Ocular surface heat flux density in healthy subjects

2021 ◽  
Vol 99 (S265) ◽  
Author(s):  
Lukyan Anatychuk ◽  
Nataliya Pasyechnikova ◽  
Volodimir Naumenko ◽  
Roman Kobylianskyi ◽  
Oleg Zadorozhnyy
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Ocular Surface ◽  
Surface Heat Flux ◽  
Healthy Subjects ◽  
Heat Flux Density ◽  
Surface Heat

Surface Heat Transfer Coefficient’s Calculation of W9Mo3Cr4V during Cryogenic Treatment

2010 ◽  
Vol 43 ◽  
pp. 424-429
Author(s):  
Zi Ran Liu ◽  
Cai Xia Ren ◽  
Xian Guo Yan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flux Density ◽  
Heat Flux Density ◽  
Cryogenic Treatment ◽  
Surface Heat ◽  
Surface Heat Transfer ◽  
Surface Heat Transfer Coefficient

In the process of the finite element analogy of the Cryogenic Treatment of the high speed steel cutter with respect to the material of W9Mo3Cr4V, the surface heat transfer coefficient is a crucial parameter. In order to get this parameter, this paper employed the method of inverse heat conduction to process the temperature curve generated through the cryogenic treatment of the tested work piece with the material of W9Mo0Cr4V, thereby obtaining the surface heat transfer coefficient of the tested work piece. This coefficient can be considered the surface heat transfer coefficient of cryogenic treatment of the cutter with the same material. The principle of the inverse heat conduction is as follows: firstly, according to the boundary condition and the initial value in the tri-dimensional space, the equation of the sensitivity coefficient and the temperature field can be deduced. Second, the coupling of two equations is carried out, and the heat flux density is calculated based on above result. The heat flux density will be revise to get the reasonable value . Lastly, the surface heat transfer coefficient can be obtained by the heat flux density. In this paper, all the work is automatically accomplished with the aid of FEPG soft ware and Visual C++ programmable language.

Сurrent situation on determination of critical value of heat flow density

2020 ◽  
pp. 99-106
Author(s):  
V.V. Nizhnyk ◽  
◽  
A.S. Borysova ◽  
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Environmental Conditions ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Continuous Process ◽  
Critical Value ◽  
Surface Heat ◽  
Process Equipment ◽  
Critical Surface

The physical process of energy transfer in the form of a certain amount of heat from a body with a higher temperature to a body with a lower temperature until the onset of thermodynamic equilibrium is a continuous process and is present in many areas of human activity. Determining the surface heat flux density makes it possible to measure and control the thermal processes of almost any object made of different materials, as well as substances in order to assess their condition. Based on a theoretical review, the article analyzes the current state to determine the critical value of the surface heat flux density depending on environmental conditions. Based on statistics and arrays of fire cards, it was concluded that every fourth fire in Ukraine can spread to adjacent buildings and structures, process equipment and natural ecosystems by spreading thermal energy with subsequent ignition. The authors consider the concept of heat flux and the concept of heat flux density, as well as define the essence of the concept of critical surface heat flux density as characteristics of heat flux. Scientists conducted a detailed analysis of literature sources, regulations and other sources of information related to this topic. Based on the research, the authors analyzed and found that the value of the surface heat flux density significantly depends on environmental conditions, namely the introduction of finely divided water into the space where the heat process and wind exposure. The authors found that to assess the value of the critical surface heat flux density, it is advisable to use the sign of flame combustion of substances and materials for the criterion base. However, to date there is no statistical base of critical values of surface heat flux density for various substances and materials, in particular those that can be used in the decoration of buildings and technological installations. The article analyzes modern approaches to determining the parameters of heat flux, as well as identifies some differences in these approaches, which allowed to formulate the purpose and relevance of further research, and identifies the main tasks to be achieved to achieve this goal.

scholarly journals METHOD OF EXPERIMENTAL RESEARCH OF THE DEPENDENCE OF THE CRITICAL SURFACE DENSITY OF THE HEAT FLOW FROM THE WIND INFLUENCE

2020 ◽  
Vol 3 (156) ◽  
pp. 200-203
Author(s):  
A. Borysova ◽  
V. Nizhnyk
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Experimental Research ◽  
Surface Heat Flux ◽  
Surface Density ◽  
Heat Flux Density ◽  
Experimental Studies ◽  
Surface Heat ◽  
Critical Surface ◽  
Wind Influence

According to the results of the analysis of methods for determining the critical value of the surface heat flux density for substances and materials, it is established that there is no single approach to determining the critical surface heat flux density for substances and materials today. The development of the method of experimental research of the dependence of the critical surface density of the heat flow from the wind influence as a basis for substantiation of the regularity of change of density of a heat stream from wind influence is an actual scientific task. The article analyzes the current state of the study of the critical surface heat flux density. A method has been developed and experimental studies of the values of the surface heat flux density from wind exposure for substances and materials have been carried out. At the time of experimental research, the regularities of the change in the heat flux density depending on the influence of the amount of airflow introduced into the study space were determined. The purpose of the study is to identify the pattern of changes in the heat flux density of substances and materials depending on the influence of the amount of airflow introduced into the study space. To achieve this goal it is necessary to justify the type and quantity of required test and measuring equipment, as well as the number, shape, and design of sample fragments, justify the methodology of experimental studies of samples under the influence of airflow of different speeds, justify the range of wind speed. The article briefly presents the procedure for conducting experimental research. The obtained data will be used for further research of the flammability of substances and materials. Keywords: critical surface heat flux density, heat flux, heat transfer, radiation heat transfer

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

THERMAL BEHAVIOR AND IGNITION OF HIGH-ENERGY MATERIALS CONTAINING B, ALB2, AND TIB2

2020 ◽  
Author(s):  
A. G. Korotkikh ◽  
◽  
V. A. Arkhipov ◽  
I. V. Sorokin ◽  
E. A. Selikhova ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Behavior ◽  
Flux Density ◽  
Ignition Delay ◽  
Delay Time ◽  
Heat Flux Density ◽  
Ignition Delay Time ◽  
High Energy ◽  
Energy Materials ◽  
High Energy Materials

The paper presents the results of ignition and thermal behavior for samples of high-energy materials (HEM) based on ammonium perchlorate (AP) and ammonium nitrate (AN), active binder and powders of Al, B, AlB2, and TiB2. A CO2 laser with a heat flux density range of 90-200 W/cm2 was used for studies of ignition. The activation energy and characteristics of ignition for the HEM samples were determined. Also, the ignition delay time and the surface temperature of the reaction layer during the heating and ignition for the HEM samples were determined. It was found that the complete replacement of micron-sized aluminum powder by amorphous boron in a HEM sample leads to a considerable decrease in the ignition delay time by a factor of 2.2-2.8 at the same heat flux density due to high chemical activity and the difference in the oxidation mechanisms of boron particles. The use of aluminum diboride in a HEM sample allows one to reduce the ignition delay time of a HEM sample by a factor of 1.7-2.2. The quasi-stationary ignition temperature is the same for the AlB2-based and AlB12-based HEM samples.

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