The improvement of the thermal insulating material thermophysical characteristics of the thermal protection elements by studying the porous structure is a promising direction of research. The article describes the effects of the porosity and coupling of the porous structure on the thermophysical characteristics of thermal insulating materials. The article uses standard systematized techniques and instruments of scientific research applied in thermophysics. The research methodology of highly-porous material thermophysical properties is based on performance of empirical laboratory investigations of the samples obtained. It was found that for the pore structure effect on the material characteristics it is rational to use the following complex indices: porosity, number of pores, pore position in space, the pore form, pore formation energy. The article shows the effect of the porous structure on the thermophysical characteristics of the material. The complex parameters of the porous structure, which will allow to develop a new method of control of the porous structure, are proposed. As a result of the experiment planning method, the regression equation of an effective coefficient of thermal conductivity for porous thermal protection structures was developed. It was established that for a more even distribution of the mixture in a volume it is necessary to minimize the size of the dispersed components, thereby increasing the area of their contacts. The experimental method revealed that the moisture evaporation caused the formation of pores inside the clay. The shape of the pores was determined using electron microscope MMP-2P, both on the sample section and surface. The clearest clay has the greatest porosity (no iron oxide and calcium oxide). The pores have a spherical shape in it. The presence of impurities reduces the material porosity due to the increased clay viscosity.

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Досліджено вплив конвекції в замкнутих порах на коефіцієнт ефективної теплопровідності теплоізоляційного матеріалу. Визначено загальний характер розподілу швидкостей ліній току конвекції в замкнутій сферичній порі з діаметрами 2-20 мм. Встановлено найбільш значимі фактори впливу на коефіцієнт ефективної теплопровідності за допомогою регресійного аналізу. Надано рекомендації щодо створення нових крупнопористих теплоізоляційних матеріалів.Ключові слова: конвекція, замкнута сферична пора, регресійний аналіз, ефективна теплопро-відність.Cheilytko A. IntroductionThe prospects of using of porous heat-insulating materials in the industry don't in doubt [1][2][3]. New porous materials appear every year. Such materials are used as heat-insulating for houses, constructions, pipelines, furnaces, dryers and other industrial equipment. In [4] the creation of new porous heat-insulating heat-proof material on the basis of composite binder and gas agent was described, but thermal properties of such material weren't given and the possibility of porosity regulation wasn't described. Despite the fact that porosity (quantity, size and pores form) influences on the effective thermal conductivity [5,6].The generalized equation of thermal conductivity is needed for assessing of the future effective thermal conductivity of porous material, but it doesn't exist. Also the generalized equation will allow controlling the thermal conductivity of porous material at the pores formation stage without numerous experiments. So, finding of the generalized equation of thermal conductivity of porous heat-insulating materials is an actual scientific task, which is useful for the industry. The object of the research and its technological auditThe object of research is the heat transfer through porous insulating materials. The most famous problem is the lack of generalized equation of thermal conductivity, it doesn't allow to predict the effective thermal conductivity of the material at the structure formation stage. The reason of it is lack of complex entrance independent factors of porous structure that influence on the effective thermal conductivity. For determining of this factors the computer simulation was used, results of it was confirmed by laboratory experiment. For finding of the generalized equation of thermal conductivity of porous heat-insulating materials the experimental design method was used. Disadvantages of the obtained equation are the narrowed application boundaries, the pore size of 2 mm, the thermal conductivity of the basic material without pores is 0,95 W/(m ⋅ K). The aim and objectives of the researchThe aims of this work are creation of the generalized equation of thermal conductivity of porous heat-insulating materials and give the practical recommendations for structure formation of such materials.To achieve that aims, next objectives must be solved: 1. Research the influence of the convection in the pores on the thermal resistance by the computer simulation.2. Confirm the obtained dependencies by the practical experiment ...

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