Сurrent situation on determination of critical value of heat flow density

Abstract

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.