Virtual test bench for the determination of the thermal properties of vacuum insulation panels

Introduction. The authors present the results of an experimental study of the thermal insulation properties of vacuum panels using a digital copy of the test bench. The subject of the study is a vacuum insulation panel in the form of a sealed parallelepiped with internal stiffeners. When the air pressure inside the body is reduced, the specific thermal resistance of such vacuum insulation panels becomes higher than that of modern insulation materials. The use of such panels as thermal insulation for land means of transport, particularly passenger carriages and refrigerator wagons, significantly reduces energy costs for heating or air conditioning the interior. Experimental determination of the thermal properties of vacuum insulation panels is time consuming and requires expensive equipment due to their considerable heterogeneity. The aim of the study is to develop a method for determining the thermal resistance of insulating materials with internal heterogeneity in the shortest possible time with acceptable accuracy.

Materials and methods. The research methods combine physical experiments on three vacuum insulation panel prototypes and numerical experiments on 3D models of these samples. Specifically, the test stand was calibrated using its digital counterpart — a virtual test bench created as a 3D model using SolidWorks software.

Results. The study of the transient thermal process on the stand model in SolidWorks Simulation allowed us to reduce the time of the physical experiment to 40 minutes and to determine the values of the effective thermal conductivity coefficient of the three vacuum insulation panel prototypes.

Discussion and conclusion. The study of the steady-state thermal process of 3D models of vacuum insulation panel prototypes in SolidWorks Simulation showed that the discrepancy between the experimental and calculated values of the effective thermal conductivity coefficient is less than 5%. The proposed method for determining the effective thermal conductivity coefficient of materials is suitable for use in the incoming and outgoing inspection of car insulation during overhaul.

1. GOST 34681-2020. Passenger cars on locomotive traction. General technical requirements. Introduction date 2021-03-01. Moscow: Standartinform; 2020, 36 p. (In Russ.).

2. Balalaev A., Parenyuk M., Arslanov I., Ziyatdinov A. Mass and heat-insulation properties of the bodies of passenger and insulated railway cars made of vacuum honeycomb panels. Journal of Applied Engineering Science. 2018;16(1):50-59. https://doi.org/10.5937/jaes16-13888.

3. Balalaev A. N., Mokshanov A. S., Popov D. A. Patent No. 2571834 (C2). B60P3/20, B61D17/18, E04B1/80. Vacuum thermal insulation product (versions): No. 2013157470/11: appl. 24.12.2013, publ. 20.12.2015. 13 p. (In Russ.).

4. British Standard BS 874. British standard methods for determining thermal insulating properties. Part 3: Tests for thermal transmittance and conductance. Section 3.1: Guarded hot-box method. Released 1986-11-28. London: British Standards Institution; 1987. 26 p.

5. British Standards BS EN 675:2011. Glass in building. Determination of thermal transmittance (U value). Heat flow meter method. Released 2011-06-30. London: British Standards Institution; 2011. 18 p.

6. British Standards BS EN ISO 8990:1996. Thermal insulation. Determination of steady state thermal transmission properties. Calibrated and guarded hot box. Released 1996-12-15. London: British Standards Institution; 1996. 26 p.

7. ISO 9869-1-2014. Thermal insulation — Building elements — In-situ measurements of thermal resistance and thermal transmittance. Released 2014-08-01. Geneva: ISO; 2014. 36 p.

8. BS EN ISO 8990:1996. Thermal insulation. Determination of steady-state thermal transmission properties. Calibrated and guarded hot box. Released 1996-12-15. London: British Standards Institution; 1998. 26 p.

9. ASTM C1046-95. Standard Practice for In-Situ Measurement of Heat Flux and Temperature on Building Envelope Components. West Conshohocken: ASTM; 2021. 10 p. https://doi.org/10.1520/C1046-95R21.

10. ASTM C1155-95. Standard practice for determining thermal resistance of building envelope components from the in-situ data. West Conshohocken: ASTM; 2021. 8 p. https://doi.org/10.1520/C1155-95R21.

11. Atsonios I. A., Mandilaras I. D., Kontogeorgos D. A., Founti M. A. A comparative assessment of the standardized methods for the in-situ measurement of the thermal resistance of building walls. Energy and Building. 2017;154:198-206. https://doi.org/10.1016/j.en-build.2017.08.064.

12. Baldinelli G. A methodology for experimental evaluations of low-e barriers thermal properties: field tests and comparison with theoretical models. Building and Environment. 2010;45(4):1016-1024. https://doi.org/10.1016/j.buildenv.2009.10.009.

13. Gaspar K., Casals M., Gangolells M. A comparison of standardized calculation methods for in situ measurements of facades U-value. Energy and Buildings. 2016;130:592-599. https://doi.org/10.1016/j.enbuild.2016.08.072.

14. Deconinck A.-H., Roels S. Comparison of characterisation methods determining the thermal resistance of building components from onsite measurements. Energy and Buildings. 2016;130:309-320. https://doi.org/10.1016/j.enbuild.2016.08.061.

15. Desogus G., Mura S., Ricciu R. Comparing different approaches to in situ measurement of building components thermal resistance. Energy and Buildings. 2011;43(10):2613-2620. https://doi.org/10.1016/j.enbuild.2011.05.025.

16. Chaffar K., Chauchois A., Defer D., Zalewski L. Thermal characterization of homogeneous walls using inverse method. Energy and Buildings. 2014;78:248-255. https://doi.org/10.1016/j.enbuild.2014.04.038.

17. Arya F., Moss R., Hyde T., Shire S., Henshall P., Eames P. Vacuum enclosures for solar thermal panels. Part 1: Fabrication and hot-box testing. Solar Energy. 2018;174:1212-1223. https://doi.org/10.1016/j.solener.2018.10.064.

18. Arya F., Moss R., Hyde T., Shire S., Henshall P., Eames P. Vacuum enclosures for solar thermal panels. Part 2: Transient testing with an uncooled absorber plate. Solar Energy. 2018;174:1224-1236. https://doi.org/10.1016/j.solener.2018.10.063.

19. Dulnev G. N. The theory of thermal regular regime and its application to the determination of thermal characteristics. International Journal of Heat and Mass Transfer. 1960;1(2-3):152-160. https://doi.org/10.1016/0017-9310(60)90019-3.

20. Nekhendzi E. J. Method of a regular regime for the determination of variable thermal coefficients. International Journal of Heat and Mass Transfer. 1961;3(4):311-320. https://doi.org/10.1016/0017-9310(61)90046-1.

21. Golubin A. A., Belova N. V., Naumenko S. N. Effect of measurement errors in determining the heat transfer coefficient of the enclosing structures of an isothermal car. Russian Railway Science Journal. 2019;78(2):100-104. (In Russ.). https://doi.org/10.21780/2223-9731-2019-78-2-100-104.

22. Balalaev A. N., Timkin D. M. Theoretical and experimental studies of a vacuum panel with a cellular structure. International Research Journal. 2021;(8):39-47 (In Russ.). https://doi.org/10.23670/IRJ.2021.110.8.006.