Control of the thermophysical characteristics of building materials by the adaptive method using microwave heating

Abstract

An increase in the cost of energy resources and urgent character of the problem of resource conservation entailes the necessity of developing means of operational control of the thermophysical characteristics of building materials, including those synthesized using nanoparticles. The goal of the study is developing of the new method for determining the thermophysical characteristics (thermal diffusivity and thermal conductivity) of building materials. The method for determining the thermophysical characteristics proposed in this article consists in measuring the temperature in two points on the sample surface subjected to thermal pulsed impact of focused microwave radiation of the given power. The number of pulses and their frequency are adaptively set by the microprocessor information-measuring system, with which the method is implemented when the temperature is reached at the setpoint control point. To implement the method, a microprocessor information-measuring system is presented. The accuracy of the proposed method is improved by controlling high temperature values, taking information in a pulse-frequency form and heating a large bulk of the material under study. The samples of clay, concrete, silicate and red brick are studied. The data obtained were compared with the results of traceable measurements of the thermophysical characteristics of the samples, using IT-λ-400 devices under laboratory conditions. The experiments showed that the developed method has several advantages compared to other traditional methods and accuracy sufficient for thermophysical measurements. The method can be used in various fields of industry and thermal engineering for construction.