EXPERIMENTAL INVESTIGATION OF R600A REFRIGERANT FLOW INSIDE ADIABATIC CAPILLARY TUBE

Year 2016, Volume: 34 Issue: 2, 241 - 252, 01.06.2016

Tolga Apaydın Hasan Heperkan

Abstract

Capillary tubes are often used as an expansion component in the refrigeration systems of household refrigerators. During the flow of the refrigerant inside the capillary tube, due to pressure loss of the refrigerant, the refrigerant starts boiling and towards the end of the capillary tube, different types of two-phase regimes occur. Therefore; the refrigerant flow inside the capillary tube is a complex phenomenon and there are many experimental and numerical studies analyzing this refrigerant flow. However; in literature there are hardly any experimental studies analyzing refrigerant flow in small scale refrigeration systems using isobutane (R600a) as the refrigerant. In this study, the two-phase flow regimes of the R600a refrigerant inside a vertical adiabatic capillary tube with 0.80 mm inner diameter, under different condensation pressures subcooling degrees and capillary tube lengths, are recorded via high-speed camera; and the effects of different parameters on refrigerant mass flow are analyzed. The boundary conditions for the condensation pressure, subcooling degree and capillary tube length are determined in accordance with a small scale refrigeration system.

Keywords

Capillary tube, isobutane, two-phase flow, flow visualization.

References

• [1] Melo C., Ferreira R.T.S., (1999). An experimental analysis of adiabatic capillary tubes, Appl. Thermal Eng. 19, 669–684.
• [2] Choi J., Kim Y., Kim H.Y., (2003). Generalized correlation for refrigerant mass flow rate through adiabatic capillary tubes, Int. J. Refrigeration 26, 881– 888.
• [3] Fiorelli F.A.S., Huerta A.A.S., Silvares O.M., (2002) Experimental analysis of refrigerant mixtures flow through adiabatic capillary tubes, Exp. Thermal Fluid Sci. 26, 499–512.
• [4] Choi, Kim Y., Chung J.T., (2004). An empirical correlation and rating charts for the performance of adiabatic capillary tubes with alternative refrigerants, Appl. Thermal Eng. 24, 29–41.
• [5] Jabaraj D.B., Kathirvel A.V., Lal D.M., (2006) Flow characteristics of HFC407C/ HFC600a/HC290 refrigerant mixture in adiabatic capillary tubes, Appl. Thermal Eng. 26, 1621–1628.
• [6] Pate M.B., Tree D.R., (1984). An analysis of pressure and temperature measurements along a capillary tube – suction line heat exchanger, ASHRAE Trans. 90, 291–301.
• [7] Melo C., Vieira L.A.T., Pereira R.H., (2002). Non-adiabatic capillary tube flow with isobutane, Appl. Thermal Eng. 22, 1661–1672.
• [8] Bolstad M.M., R.C. Jordan, (1948). Theory and use of the capillary tube expansion device, Refrigerating Eng. 56, 577–583.
• [9] Motta S.F.Y., Parise J.A.R., (2002). A visual study of R-404A/oil flow through adiabatic capillary tubes, Int. J. Refrigeration 25, 586–596.
• [10] Cooper L., Chu C.K., (1957). Simple Selection method for capillaries derived from physical flow conditions, Refrigerating Eng., 37–41.
• [11] Mikol E.P., (1963). Adiabatic single and two-phase flow in small bore tubes, ASHRAE J. 5, 75–86.
• [12] Koizumi H., Yokoyama K., (1980) Characteristics of refrigerant flow in a capillary tube, ASHRAE Trans. 80, 19–27.
• [13] Bansal P.K., Rupasinghe A.S., (1996). An empirical model for sizing capillary tubes, Int. J. Refrigeration 19, 497–505.
• [14] Wolf D.A., Bittle R.R., Pate M.B., (1995). Adiabatic capillary tube performance with alternative refrigerants, ASHRAE Res. Project RP-762.
• [15] Schenk M., R. Oelrich, (2014). Experimental investigation of the refrigerant flow of isobutane (R600a) through adiabatic capillary tubes, Int. J. Refrigeration 38, 275-280.
• [16] Hermes, C.J.L., Melo, C., (2010). Algebraic solution of capillary tube flows Part I: adiabatic capillary tubes. Appl. Therm. Eng. 30, 449-457.
• [17] Yang L., Zhang C-L., (2009). Modified neural network correlation of refrigerant mass flow rates through adiabatic capillary and short tubes: extension to CO2 transcritical flow. Int. J. Refrigeration, 32, 1293-1301.