UDK 681.3 : 536.24.08
THE MEASUREMENT OF THE CONDENSATE FILM THICKNESS OF THE WORKING FLUID BY MEANS OF THE CAPACITIVE SENSORS IN THE LOW-TEMPERATURE RANGE HEAT PIPES
А. V. Seryakov, Yu. E. Mikhailov, S. L. Shakshin
LLC “NPP “MEDGAZ”; 29, Mozhaiskoe shosse, Moscow, 121471, Russian Federation
The description of the automated capacitive meter of local thickness of the condensate film of working fluid in the low-temperature range short heat pipes are presented. The design, calibration results of the open small-sized capacitive sensors and electronics that allows the determination of the local thickness of the film of working fluid on the condensation surface of the within heat pipes designed for cooling the heat-stressed designs of spacecraft are presented. The cooling system of the spacecraft on the basis of heat pipes (HPs) can have complex spatial and different topological configuration. The movement of the working fluid in such systems must be carefully examined in the terrestrial environment and determined boundary and limit settings and ranges of stability of HPs work. For such studies modern measuring equipment, which must be inserted into the outlets of HPs to control the thickness, temperature and later the flow rate of the film coolant, is required. The developed electronic hardware, mounted on small circuit boards directly on the lids of short HPs, consists of a measuring and a reference frequency generators, mixer and low pass filter. Both generators are performed on two identical broadband amplifiers EL4551 (INTERSIL), providing amplification of signals with frequency up to 90 МHz. The scheme of each generator is created on the serial LC resonant circuit, in parallel to the capacitance of which is connect with the measuring and reference capacitive sensors in the measuring and reference HPs. With the outputs of the amplifiers of the measurement and reference signals are fed to the inputs of the balanced type mixer ADE-1, then the low pass filter, oscilloscope and a computer. The average time values of the condensate film thickness depending on the heat load on the capillary-porous evaporator have been measured. The measurement error does not exceed 2·10–3 mm. It is shown that the condensate film thickness decreases sharply with increase of heat load on the evaporator is a short low-temperature range HPs, thermal resistance of film on the condensation surface reaches 60 % of the total thermal resistance of the short HPs with capillary-porous evaporator.
Keywords: capacitive sensors, condensate film thickness, high-frequency generators, heat pipes.
References

1. Seryakov A. V. Pulsation flow in the vapour channel of short low temperature range heat pipes. International Journal on Heat and Mass Transfer Theory and Application. 2014, Vol. 2, No. 2, P. 40–49.

2. Seryakov A. V., Ananiev V. I., Orlov A. V. [Condensation research in the short low-temperature range heat pipes]. Proceedings of the IX Minsk International Seminar of Heat Pipes, Heat Pumps, Refrigerators, Power Sources. Minsk, Belarus, 7–10 September 2015, Vol. 2, P. 168–176.

3. Seryakov A. V., Ananiev V. I. [Condensation research in the short low-temperature range heat pipes]. Proceedings of the VIII International Symposium on Turbulence, Heat and Mass Transfer. Sarajevo, Bosnia and Herzegovina, September 15–18, 2015. Begell House Inc. P. 693–696.

4. Seryakov A. V., Konkin A. V. [Numerical simulation of pulsations in vapour channel of lowtemperature range heat pipes]. Proceedings of the VIII International Symposium on Turbulence, Heat and Mass Transfer. Sarajevo, Bosnia and Herzegovina, September 15–18, 2015. Begell House Inc. P. 677–680.

5. Iossel Y. Ya., Kochanov E. S., Strunskiy M. G. Raschet elektricheskoy emkosti. [The calculation of the electric capacity]. Leningrad, Energoizdat Publ., 1981, 288 p.

6. Foreit I. Emkostnye datchiki neelektricheskikh velichin. [Capacitive sensors of non-electrical quantities]. Moscow, Energiya Publ., 1960, 160 p.

7. Rogovaya A., Olevskiy V. M., Rinova N. S. [Measurement of the thickness and profile of the liquid film]. Pribory I tekhnika eksperimenta. 1968, No. 1, P. 189–192 (In Russ.).

8. Ozgu M. R., Chen J. C., Eberhardt N. A capacitance method for measurement of film thickness in two-phase flow. Review of Scientific Instruments. 1973, Vol. 44, P. 1714–1716.

9. Klausner J. F., Zeng L. Z., Bernhard D. M. Development of a film thickness probe using capacitance for asymmetrical two-phase flow with heat addition. Review of Scientific Instruments 1992, Vol. 63, P. 3147–3152.

10. Krotov S. V., Nazarov A. D., Pavlenko A. N., Pecherkin N. I., Serov A. F., Chexovich V. Y. [Capacitive meter of local thickness of liquid film]. Pribory I tekhnika eksperimenta. 1997, No. 1, P. 149–152 (In Russ.).

11. Alekseenko S. V., Nazarov A. D., Pavlenko A. N., Serov A. F., Chexovich V.Y. [The flow of the cryogenic liquid film on a vertical surface]. Thermophysics and Aeromechanics. 1997, Vol. 4, No. 3, P. 307–317 (In Russ.).

12. Pavlenko A. N., Lel V. V., Serov A. F., Nazarov A. D. [Flow dynamics of intensively evaporating wave liquid film]. Prukladnaya Mexanika I Texnicheskaya Physica. 2001, Vol. 42, No. 3, P. 107–115 (In Russ.).

13. Alekseenko S. V., Nakoryakov V. E., Pokusaev B. G. Volnovoe Techenie plenok zhidkosti. [The wave flow of liquid films]. Novosibirsk, Nauka Publ., 1992, 256 p.

14. Thorncroft G. E., Klausner J. F. A Capacitance sensor for two-phase liquid film thickness measurements in a square duct. Journal of Fluids Engineering. 1997, Vol. 119, No. 1, P. 164–169.

15. Capacitive sensing of droplets for microfluidic devices based on thermocapillary actuation The Royal Society of Chemistry. Lab Chip. 2004, Vol. 4, P. 473–480.

16. Tibiriçá C. B., Nascimento F. J., Ribatski G. Film thickness measurement techniques applied to micro-scale two-phase flow systems. Experimental Thermal and Fluid Science. 2010, Vol. 34, P. 463–473.

17. Seryakov A. V. Emkostnyy datchik opredeleniya tolshchiny sloya zhidkosti. [Capacitive sensor for determining the liquid layer thickness]. Patent RF, No. 152108, 2015.

18. Seryakov A. V., Konkin A. V., Belousov V. K. [The application of steam jet nozzle in heat pipes of medium temperature range]. Vestnik SibGAU. 2012, No. 1(41), P. 142–147 (In Russ.).

19. Seryakov A. V. Velocity measurements in the vapour channel of low temperature range heat pipes. International Journal of Engineering Research & Technology, 2013, Vol. 2, No. 8, P. 1595–1603.

20. Axadov Ya. Y. Dielektricheskie svoistva chistykh zhidkostey. [Dielectric properties of pure liquids]. Moscow, Izdatelstvo Standartov Publ., 1972, 412 p.

21. Key D., Lebi T. Tablitsy fyzicheskikh i khimicheskikh postoyannykh. [Tables of physical and chemical constants]. Moscow, Gosudarstvennoe izd-vo phyzikomatematicheskoy literature Publ., 1962, 247 p.

22. Tablitsy fyzicheskikh velichin. Spravochnik. [Tables of physical and chemical constants. Handbook]. Ed. Kikoina I. K. Moscow, Atomizdat Publ., 1976, 1008 p.

23. Rabinovich V. A., Xavin Z. Ya. Kratkiy khimicheskiy spravochnick [Brief chemical Handbook]. Ed. Potexin A. A., Efimov A. I. St. Petersburg, Khimiya Publ., 1994, 432 p.

24. Fernandes D. P. et al. A formulation for the static permittivity of water and steam at temperatures from 238K to 873K at pressures up to 120 MPa, including derivatives and Debye-Huckel coefficients. Journal of Physical and Chemistry Reference Data. 1997, Vol. 26, P. 1125–1166.

25. Fernandes D. P. et al. A database for the static dielectric constant of water and steam. Journal of Physical and Chemistry Reference Data. 1995, Vol. 24, No. 1, P. 33–69.

26. Seryakov A. V. [Temperature measurement with thermistors]. Vestnik SibGAU. 2013, No. 1(47), P. 167–172 (In Russ.).

27. Seryakov A. V. [Improving the accuracy of the temperature measurement with thermistors]. Datchiky i Systemu. 2013, No. 1, P. 38–42 (In Russ.).

28. Seryakov A. V. A new method for temperature measurement using thermistors. International Journal of Engineering Research & Technology. 2013, Vol. 2, No. 7, P. 444–454.

29. Seryakov A. V. A universal method for temperature measurement using thermistors. National Journal of Engineering and Technology  Research. Academia Publishing. 2013, Vol. 1(1), P. 014–020.


Seryakov Arkadiy Vladimirovich – Cand. Sc., senior researcher, LLC “NPP “MEDGAZ”. Е-mail: seryakovAV@yandex.ru.

Mikhailov Yuri Еvgen’evich – leading engineer, LLC “NPP “MEDGAZ”. Tel. (8162) 62-17-35.

Shakshin Sergey Leonidovich – leading engineer, LLC “NPP “MEDGAZ”. Tel. (8162) 62-20-21.