The analysis of the results of the instrumental thermal engineering survey of 22 multi-apartment residential buildings built of silicate and ceramic bricks or reinforced concrete panels, with a service life of buildings of more than 40–50 years, carried out before major repairs is given. Thermal calculations to determine the savings in energy resources showed an average value of savings in thermal energy after insulation of 28 %. Typical defects of enclosing structures identified during thermal imaging examination are presented and systematized. An external examination by infrared thermography is carried out with a thermal imager, followed by processing of thermograms. The absence of influence of the results of thermal imaging examination on the parameters of the insulation is shown. The results of measurements of resistance to heat transfer are presented. The measurements are made using ten-channel heat flux density and temperature meters. The actual measured heat transfer resistance deviated from the design resistance by an average of 16 per cent to 33 per cent. The heat transfer resistance of the wall before insulation is much less than the value of the heat transfer resistance of the insulation and the final resistance of the multilayer wall structure. The error in determining the thermal resistance of the insulated wall does not affect the required thickness of the insulation. It is concluded that the instrumental examination of the enclosing structures of buildings before a major overhaul seems to be redundant. It is recommended to use a typical thickness of insulation during the overhaul of Soviet-built residential buildings, which for the climatic conditions of the Belgorod Region will be 10 cm of mineral wool insulation.
The computational method of diffusion approach, used sometimes for simulating the radiative heat transfer, differs in simplicity of its algorithm, but can not take ac-count of radiation anisotropy. The reasons of its insufficient accuracy have been re-vealed; it is shown that inadequate boundary con-ditions produce unpredictable er-rors. Ways for eliminating short-comings of the diffusion method have been developed. The accurate diffusion model has been theoretically elaborated for radiative heat transfer in dust-laden gases. To eliminate singularity of temperature curves on the surface of confining walls, the en-closed extinction medium was hypothetically considered as an unbounded one. The radiation intensity has been expanded in a se-ries and integrated over the spherical solid angle, what has allowed to obtain more precise differential equation for the resulting radiation flux both in the unbounded and enclosed extinction medium. As a result, shortcomings peculiar to the previous method of diffusion approach have been eliminated, and correct Neumann and Robin boundary conditions have been formulated. As a result, the elaborated diffu-sion model got the increased accuracy in simulating radiative heat transfer, and con-currently it offers an advantage of simplicity and universality of the diffusion ap-proach method.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.