Problem of Measuring Thermal Conductivity of Polyurethane Thermal Insulation of Liquid Hydrogen Tanks for Launch Vehicle in Operational Environment
20th International Scientific Conference "Engineering for Rural Development": Proceedings. Vol.20 2021
Sergey Kravchenko, Nikolajs Kuļešovs, Natalia Panova, Ugis Cabulis, Romass Pauliks, Sergejs Bratarčuks, Vladimirs Šestakovs

The problem of polyurethane cryogenic thermal insulation quality control has become more and more urgent. Such thermal insulation has a wide range of applications from space technology to medical technology. In comparison with traditional cryogenic thermal insulation, such as screen-vacuum, vacuum-zeolite, vacuum-perlite, and vacuum-fibre insulation, polyurethane thermal insulation has some undeniable advantages, such as low cost, high manufacturability and low labour intensity of the insulation of the structure, no need for periodic maintenance, high resistance to vibration, shock, etc. At the same time, full reproducibility of insulation properties is a problem. To guarantee successful use of the thermal insulation, especially in such critical areas as space industry applications, it is necessary to monitor its thermal conductivity in the range of operating temperatures as the main parameter that determines consumer properties. Measuring the thermal conductivity of materials is quite difficult, since thermal conductivity cannot be measured directly. It is even more difficult to measure thermal conductivity in space technology operating conditions - in a vacuum and low temperatures. SIA Cryogenic and vacuum systems, the Latvian State Institute of Wood Chemistry, and the Ventspils University of Applied Science, in the framework of the EDRF financed “Cryosiltmer” project are developing a low-temperature thermal conductivity measurement method and a test facility on its basis. It will measure the thermal conductivity of polyurethane thermal insulation in air pressure/vacuum or helium environment in the cold end temperature range of 10-30 K. The project development is quite complicated, because to obtain correct measurement of thermal conductivity, it needs to minimize the temperature field gradients in the measurement system in such temperature range. During the project implementation the measurement system thermal environment model was developed. The modelling results showed that it is impossible to use directly the method used in existing NASA facility due to the reasons of great thermal loses. Then, the modelling helped find the solution, which allows to use a market available cryogenic cooler to make the measuring facility - to design proper intermediate liquid nitrogen cryostat. Now the facility is under assembling and testing. Preliminary vacuum and cryogenic tests show proper functioning of the cryostat and its capability to high vacuum operation. The proposed approach, described in the paper can help solve the problem of the thermal conductivity measurement under liquid hydrogen temperatures. After confirmation of the thermal conductivity stability in the created test facility the polyurethane thermal insulation will be used in liquid hydrogen tanks of the ESA “Ariane-6” launch vehicle.

Atslēgas vārdi
cryogenics, polyurethane, thermal conductivity

Kravchenko, S., Kuļešovs, N., Panova, N., Cabulis, U., Pauliks, R., Bratarčuks, S., Šestakovs, V. Problem of Measuring Thermal Conductivity of Polyurethane Thermal Insulation of Liquid Hydrogen Tanks for Launch Vehicle in Operational Environment. No: 20th International Scientific Conference "Engineering for Rural Development": Proceedings. Vol.20, Latvija, Jelgava, 26.-28. maijs, 2021. Jelgava: Latvia University of Life Sciences and Technologies, 2021, 1795.-1803.lpp. ISSN 1691-5976. Pieejams: doi:10.22616/ERDev.2021.20.TF394

Publikācijas valoda
English (en)
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