Badanie niestabilności skraplania proekologicznego czynnika chłodniczego w minikanałach rurowych

• Autorzy: Bohdal T. , Charun H. , Kuczyński W.

Warianty tytułu

EN

Investigation of the instability of the condensation of environmentally friendly refrigerant in pipe minichannels

• Języki publikacji: PL

Abstrakty

PL

Celem niniejszych badań było rozpoznanie tego problemu i stwierdzenie, czy zjawiska rozprzestrzeniania się niestabilności w mini-kanałach podczas skraplania mogą być porównywalne do tych, które są znane dla kanałów konwencjonalnych. Należy wskazać, że w skraplaczu chłodniczym pracującym w warunkach eksploatacyjnych zaburzenia mogą być generowane impulsowo (skokowo) [5] lub periodycznie [6]. Przykładowo, skokowe zamknięcie lub otwarcie zaworu na zasilaniu wężownicy skraplacza wywołuje typowe zaburzenia impulsowe, które mogą wywołać niestabilności związane np. z rozwojem lub zanikiem skraplania czynnika chłodniczego. W dalszej części opracowania przedstawiono wyniki badań eksperymentalnych wpływu zaburzeń generowanych periodycznie na proces skraplania czynnika chłodniczego w mini-kanałach rurowych skraplaczy kompaktowych.

EN

Under real conditions, the work of conventional and compact refrigerating machines and devices (with exchangers which construction is based on the use of mini-channels or micro-channels) is subject to a lot of disturbances which are the result of both external and internal impacts. Such phenomena occur very frequently in the operational practice. The cause of disturbances may be the start-up or the stoppage of the installation, a change of the heat load of the exchangers, opening or closing of the valves, the work of automatic control elements etc. Considering the above, investigations on the condensation of the refrigerant in the flow in pipe mini-channels in the conditions of external disturbances were conducted. The development or decay of condensation was produced through a unitary change of the parameters of the two-phase system, e.g. the pressure and the mass flux density in the pipe channel. It was confirmed that two-phase media exhibit wave properties, while the disturbances produced displaced with a finite velocity. It was demonstrated that in contrast with conventional channels, the value of the boundary velocity of the displacement of pressure disturbances is obtained in mini-channels with substantially lower frequencies of their generation. Investigations were conducted with the use of a compressor refrigerating cycle with the environmentally friendly R404A refrigerant.

Słowa kluczowe

PL

czynnik chłodniczy; skraplanie; minikanały rurowe

EN

refrigerant; liquefaction; pipe minichannels

• Wydawca: Politechnika Koszalińska
• Czasopismo: Rocznik Ochrona Środowiska
• Rocznik: 2011
• Tom: Tom 13
• Strony: 377--391
• Opis fizyczny: Bibliogr. 16 poz.

Twórcy

autor

Bohdal T.

autor

Charun H.

autor

Kuczyński W.

• Politechnika Koszalińska

Bibliografia

• 1. Agarwal A., Bandhauer T.M., Garimella S.: Measurement and modeling of condensation heat transfer in non-circular microchannels. Int. Journal of Refrigeration. pp. 1÷11. 2010.
• 2. Bilicki Z., Kardaś D., Michaelides E.E.: Relaxation models for wave phenomena in liquid – vapour bubble flow in channels, J. Fluids Engineering, No. 120, pp. 369÷377. 1998.
• 3. Bohdal T., Łomiak M.: Condensation of refrigeration medium under condition of unit disturbances. An International Journal of Turbulence, Volume 11, pp. 221÷224. 2005.
• 4. Bohdal T.: Investigation of boiling of refrigerating medium under conditions of impulse disturbances. An International Journal of Experimental Heat Transfer, Volume 17, No 2, pp. 103÷117. 2004.
• 5. Bohdal T.: Development of bubbly boiling in refrigeration heat exchangers. An International Journal of Heat Exchangers, No 1, Volume V, pp. 179÷199. 2004.
• 6. Bohdal T., Kuczyński W.: Investigation of boiling of refrigeration medium under periodic disturbance conditions. An International Journal of Experimental Heat Transfer, Volume 18 , No 3, pp. 135÷151. 2005.
• 7. Bohdal T., Łomiak M.: Condensation of refrigeration medium under external disturbances. JP Journal of Heat and Mass Transfer, Volume 2, Issue 3 pp. 303÷328. 2008.
• 8. Coleman J.W., Garimella S.: Two-phase flow regimes in round square and rectangular tubes during condensation of refrigerant R134a. Int. Journal of Refrigeration. Vol. 26, no 1, s. 117÷128. 2003.
• 9. Dobson M.K., Chato J.C.: Condensation in smooth horizontal tubes. I. Heat Transfer ASME. Vol. 120, pp. 193÷213. 1998.
• 10. Nakoryyakov V.E., Pokusaev B.G., Shreiber I.R.: Wave propagation in gas-liquid media, Bergles A.E. (Editor) by CRC Press Inc., Boca Raton, Florida 1993.
• 11. Nigmatulin R.I.: Dynamics of multiphase media. Hemisphere. New York 1990.
• 12. Nosoko T., Yoshimura P.N., Nagata T., Oyakawa K.: Characteristics of two-dimensional waves on a falling liquid film. Chem. Eng. Sci. Vol. 51 (5), pp. 725÷732. 1996.
• 13. Park S.K., Kim M.H., Yoo K.J.: Condensation of pure steam and steam-air mixture with surface waves of condensate film on a vertical wall. Int. J. Multiphase Flow. Vol. 22, No 5, pp. 893÷908. 1996.
• 14. Su Q., Yu G.X., Wang H.S., Rose J.W.: Microchannel condensation: Correlations and theory. Int. Journal of Refrigeration. 2009.
• 15. Tandon T.N.: Heat transfer during forced convection condensation inside horizontal tube. Int. J. of Refrigeration. Vol. 18, no. 3, pp. 156÷162. 1995.
• 16. Webb R.L., Ermis K.: Effect of hydraulic diameter on condensation of R134a in flat extruded aluminum tubes. J. Enhanced Heat Transfer. Vol. 8(2), s. 77÷90. 2001.