КОНДУКТИВНЫЙ ТЕПЛОПЕРЕНОС В СЛОЕ ТОНКОПЛЕНОЧНОЙ ТЕПЛОВОЙ ИЗОЛЯЦИИ

Translated title of the contribution: Conductive heat transfer in layer of thin7film thermal insulation

Research output: Contribution to journalArticle

Abstract

The relevance of the study is caused by the need to create new energy/saving technologies for thermal protection of elements of heat supply systems and other energy equipment for various purposes. The high level of heat losses in heat supply systems (for example, heat networks, thermal power plants, boiler) and power equipment for various purposes (chemical production, food industry, etc.) and the unsatisfactory condition of their thermal insulation justify the need to develop new technologies to reduce heat losses in the systems in question. The unique thermophysical characteristics of thin/film thermal insulation coatings allow their use in various energy systems and equipment. Despite this, the technology of using thin/film heat/insulating coatings has not been developed. This is due to several reasons, the main of which are: lack of knowledge about the physical properties and mechanisms of heat and mass transfer processes in thin/film heat/insulating coatings. The main aim of the research is a study of conductive heat transfer in the layer of thin/film thermal insulation taking into account the heterogeneity of the properties of microspheres and binders. Objects of the research are cylindrical layers of thin/film thermal insulation. It is assumed that constant temperatures are maintained on the inner and outer surfaces. Two variants of the geometry of the thin/film heat/insulating coating were considered: «binder and full/ bodied microspheres» and «binder and hollow microspheres». The studies were conducted for 0,33 mm insulation layer. The temperatures on the inner and outer surfaces of the insulation were taken in accordance with the experimental data. It was assumed that 62 % of the thin/film thermal insulation layer consists of microspheres with a diameter of 50 micrometers and 38 % of a binder. Two types of hol/ low microspheres with wall thicknesses were considered: 5 and 2 micrometers. Methods. The solution of the problems posed is obtained by the finite element method. Galerkin approximation, non/uniform finite ele/ ment mesh were used. The parameters of the grid elements were chosen from the conditions of convergence of the solution. An incre/ ase in the number of elements of the computational grid was carried out using the Delaunay method. Experimental studies were carried out with the original laboratory stand. Results. It was established that the average thermal conductivity coefficient of a thin/film heat/insulating coating in the temperature range of 50–90 °C is 0,0574 W/(mK), which differs significantly from the value stated by the manufacturer. The effect on the thermal losses of the type of binder and the characteristics of the microspheres (hollow or full/bodied), the wall thickness of the microsphere and the gas phase contained in the cavity of the microsphere is revealed. For the case under consideration, the deviation from the expe/ rimental data ranged from 9,36 to 91,12 %, depending on the composition of the thin/film thermal insulation coating. This is due to a sharp change in the effective thermophysical properties of thermal insulation with different characteristics of the components of thin/ film thermal insulation. Analysis of the results of numerical simulation allows us to conclude that the most likely composition of thin/film thermal insulation includes hollow microspheres and a multicomponent binder.

Original languageRussian
Pages (from-to)189-197
Number of pages9
JournalBulletin of the Tomsk Polytechnic University, Geo Assets Engineering
Volume330
Issue number5
DOIs
Publication statusPublished - 1 Jan 2019

    Fingerprint

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology
  • Waste Management and Disposal
  • Economic Geology
  • Management, Monitoring, Policy and Law

Cite this