Kovtun S. Scientific and technical principles for ensuring the unity of measurement of the surface density of heat flux

The thesis is devoted to the development of theoretical foundations, methodological apparatus and improvement of the reference base for ensuring the unity of measurements of the surface density of heat flux in a wide range that satisfies the needs of thermal measurements in various fields of scientific and applied research. A methodology for ensuring the unity of measurements of the surface heat density of the heat flux has been developed; the uncertainty of the measurement of the surface density of the heat flux and the main factors of influence has been studied in order to form a homogeneous and stationary heat flux on the sensor surface to ensure the implementation of a unit of measurement with a given level of uncertainty. To substantiate the possibility of extending the range of measurement of the surface heat density, a mathematical model is proposed that illustrates the relationship between the reproduction unit of the unit of measurement and individual components of the uncertainty that affects the accuracy of forming the unit of measurement for different heat transfer processes. The conceptual model of the implementation of the standard density of heat flux according to the modular principle is proposed, the features of which are the use of different methods of formation and transmission of thermal energy and a single module for the registration and processing of measurement information. This allowed the order of magnitude to expand the lower and upper limits of the working range of measurements, which corresponds to the world level metrological support for measuring the surface density of the heat flow. The variants of constructive execution of the measuring cells of the thermal unit for reproduction of the surface density of the heat flow, as well as means of transmitting the size of the unit of measurement and the hardware and software that implement the proposed concept of the modular construction of the standard are developed. The estimation of the total uncertainty of reproduction and transfer of the unit of measurement of the surface density of the heat flow has been carried out, and the methods of studying the metrological characteristics of the means of measuring the density of the heat flow have been developed and experimental research has been carried out. The information-measuring technology for ensuring the unity of measuring the surface density of the heat flow has been developed, which allowed to adapt the main provisions of the metrological provision of thermal quantities to specific spatial and time arguments of the implementation of the process of measuring the surface density of the heat flow and expand the scope of the application of heat sensors stream.