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In relation to question of development of controls, test of heatcover materials, for defence of workers of dsns of Ukraine

Journal: Bulletin of Prydniprovs'ka State Academy of Civil Engineering and Architecture (Vol.2020, No. 6)

Publication Date:

Authors : ;

Page : 148-155

Keywords : thermal radiation; workplaces; thermal processes; heat flow sensor; nomogram; simulation;

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Abstract

Development of means of control, testing of heat-protective materials used for the manufacture of personal protective equipment, both existing and at the stage of creating new ones. Method. Heat-protective materials for special clothing must be tested according to the nomenclature of quality indicators. We have considered the most important, which are associated with the effects of high-intensity heat radiation and high temperature. Results. The solution of the approximate value of the area of existence of the test method is offered. The test method is based on two methods. Previous: the test specimen is clamped in the frame and electric welding is performed near its surface. Particles of molten metal fall on the surface of the sample and leave traces in the form of burns, sticky particles. The depth of burn, the degree of adhesion, etc. are investigated. Currently, a more advanced method is used - the method of melting the welding electrode by blowing on the surface of the test material. However, both methods allow to obtain hot drops of different sizes, different weights, different directions relative to the test material and uncontrolled heating temperature of the hot drop, which does not allow to obtain high reliability of the results of the study. We proposed to create a device that allows you to control the size of the drop, the kinetic energy of the impact, the direction of flight and the temperature of the hot particle. All the above determined the direction of work on creating a methodology for studying these parameters and, as follows, the requirement to create an installation that would ensure the stability of parameters such as mass, velocity, temperature and flight trajectory of heated metal particles with the possibility of controlled change of these parameters. All the above determined the direction of work on creating a methodology for studying these parameters and, as follows, the requirement to create an installation that would ensure the stability of parameters such as mass, velocity, temperature and flight trajectory of heated metal particles with the possibility of controlled change of these parameters. To determine the area of existence of the research criteria by the proposed method, it is necessary to solve the problem with the following assumptions: the shape of a drop of metal is taken in the form of an ideal sphere; the droplet size is taken as the average; the drop is suspended on a non-thermally conductive thin thread in the air; air movement is excluded; heat transfer due to thermal conductivity is excluded from the calculation; the calculation does not take into account the process of oxidation of the surface of the hot drop and the formation of scale; the crystallization time of the metal is not taken into account. The process of influence of the hot metal ball on the investigated material is conditionally divided into three stages: heating of the ball to the set temperature and its control; the flight of the ball in the air with its subsequent cooling; the impact of the ball on the surface of the sample with the transfer of kinetic and thermal energy. In addition, it is necessary to control the force and set the direction of impact of the particle relative to the test material. The calculation of heat transfer processes is a complex mathematical problem that involves solving many systems of nonlinear equations. Using certain assumptions, we accept two mechanisms of heat transfer - molecular and convective. Scientific novelty. For the first time, a new method is proposed that allows to supplement the existing and get more reliable results. Practical meaningfulness. The installation of research of heat-protective materials on spark resistance is developed.

Last modified: 2021-01-04 22:32:26