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

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.

non-destructive testing, thermal diffusivity, thermal conductivity, microwave heating, thermal engineering for construction, microprocessor system

1. Klyuev V. V. Devices for non-destructive testing of materials and products. Directory. — Moscow: Mashinostroenie, 1976. — 182 p. [in Russian].

2. Chernyshov A. V., Ivanov G. N. Method of non-destructive testing of thermophysical properties of multilayer heat-shielding coatings and products / Kontrol. Diagn. 2007. N 6(108). P. 50 – 54 [in Russian].

3. Chernyshova T. I., Chernyshov V. N. Methods and means of non-destructive testing of thermophysical properties of materials. — Moscow: Mashinostroenie, 2001. — 240 p. [in Russian].

4. Golovin Yu. I. et al. A new approach and a rapid method for determining the kinetic thermal characteristics of materials / Information-sensory systems in thermophysical research: a collection of scientific articles. — Tambov: TGTU, 2018. P. 193 – 195 [in Russian].

5. Chernyshov A. V. Method of non-destructive testing of thermal characteristics of multilayer products / Kontrol. Diagn. 2003. N 6. P. 40 – 44 [in Russian].

6. Artyuhina E. L., Ponomarev S. V. Technical means of controlling the thermal diffusivity of solid non-metallic materials / Trudy TGTU. 2008. N 21. P. 87 – 89 [in Russian].

7. Golikov D. O., Chernyshov A. V., Zharikova M. V. Microwave method and measuring system for non-destructive testing of thermophysical characteristics of building materials / Problems of technological safety and sustainable development: a collection of scientific articles. — Tambov: TGTU, 2011. P. 230 – 234 [in Russian].

8. Chernyshov V. N., Zharikova M. V., Chernyshov A. V. Microwave method of nondestructive testing of the thermal characteristics of building materials / Zavod. Lab. Diagn. Mater. 2018. Vol. 84. N 10. P. 29 – 34. DOI: 10.26896/1028-6861-2018-84-10-29-34.

9. Chernyshov V. N., Chernyshova T. I. Methods and information-measuring systems for non-destructive testing of the thermophysical properties of materials and products. — St. Petersburg: Йkspertnye resheniya, 2016. — 384 p. [in Russian].

10. Ponomarev S. V., Divin A. G. Application of mathematical modeling and optimization in the design and modernization of methods and devices for thermophysical measurements / Modern methods and means of studying the thermophysical properties of substances: conference proceedings. — St. Petersburg: ITMO, 2017. P. 13 – 14 [in Russian].

11. Selivanova Z. M., Kurenkov D. S. Simulation of measuring signals of an intellectual information-measuring system for remote control of the thermophysical properties of solid materials / Information-sensory systems in thermophysical research: a collection of scientific articles. Vol. 1. — Tambov: TGTU, 2018. P. 308 – 311 [in Russian].

12. Ponomarev S. V., Divin A. G. Mathematical methods of metrology and optimization application in the design and modernization of techniques and devices for thermophysical measurements / 27th International scientific symposium «Metrology and metrology assurance 2017». Proceedings of the symposium. — Sozopol: Technical University of Sofia, 2017. P. 112 – 114.

13. Pyushner G. Heating energy ultra-high frequency. — Moscow: Йnergiya, 1968. — 312 p. [in Russian].

14. Pat. 2399911 RF, IPC G 01 N 25/18. Method for deter-mining the thermal characteristics of building materials (options) / Chernyshov V. N., Golikov D. O., Chernyshov A. V.; applicant and patent holder TSTU. — N 2008145926/28; appl. 20.11.2008; publ. 20.09.2010. Byull. N 26.

15. Lykov A. V. Theory of heat conduction. — Moscow: Vysshaya shkola, 1967. — 599 p. [in Russian].

16. Franchuk A. U. Tables of heat engineering indicators of building materials. — Moscow: NII Stroitel’noi fiziki, 1969. — 144 p. [in Russian].