Nuclear Engineering and Design 240 (2010) 3956–3966 Contents lists available at ScienceDirect Nuclear Engineering and Design journal homepage: www.elsevier.com/locate/nucengdes Experimental investigation of local two-phase flow parameters of a subcooled boiling flow in an annulus Byong-Jo Yun ∗ , Byoung-Uhn Bae, Dong-Jin Euh, Chul-Hwa Song Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353, Republic of Korea article info Article history: Received 30 August 2009 Received in revised form 5 January 2010 Accepted 11 February 2010 abstract As a series of subcooling boiling flow tests, local two-phase flow parameters were obtained at SUBO (subcooled boiling) test facility under steam–water flow conditions. The test section is a vertical annulus of which the axial length is 4.165 m with a heater rod at the center of a channel. The inner and outer diameters of the test section and the heater rod are 35.5 mm and 9.98 mm, respectively. The test was performed by a two-stage approach. Stage-I for the measurement of local bubble parameters has been already done (Yun et al., 2009). The present work focused on the stage-II test for the measurement of local liquid parameters such as a local liquid velocity and a liquid temperature for a given flow condition of stage-I. A total of six test cases were chosen by following the test matrix of stage-I. The flow conditions are in the range of the heat flux of 370–563 kW/m 2 , mass flux of 1110–2100 kg/(m 2 s) and inlet subcooling of 19–31 ◦ C at pressure condition of 0.15–0.2 MPa. From the test, local liquid parameters were measured at 6 elevations along the test section and 11 radial locations of each elevation in addition to the previously obtained local void fraction, interfacial area concentration, Sauter mean diameter and bubble velocity. The present subcooled boiling (SUBO) data completes a data set for use as a benchmark, validation and model development of the Computational Fluid Dynamics (CFD) codes or existing safety analysis codes. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Subcooled boiling phenomena occur due to the thermally non- equilibrium state in the two-phase heat transfer system such as a nuclear power plant, heat exchanger, refrigerator, etc. Many complicated phenomena such as a bubble generation, a bubble departure, a bubble growth, and a bubble condensation are created by this thermally non-equilibrium condition in the subcooled boil- ing flow. To predict precisely this subcooled boiling phenomenon, many researchers explored intensively the subcooled boiling phe- nomena based on the experiments over the last several decades. Previous fundamental experimental studies of subcooled boiling flow are found from Zeitoun (1994), Lee et al. (2002), Situ et al. (2004), Kim et al. (2004), etc. However, until now, the prediction of subcooled boiling flow has not progressed satisfactorily enough to cover the various geome- tries and the wide range of flow conditions such as a mass flux, a heat flux and a pressure. It is mainly caused by the facts that the basic mechanism of subcooled boiling flow was not fully understood and an available experimental database for the devel- opment of mechanistic subcooled boiling flow model is still limited to the narrow range of flow conditions and geometry due to ∗ Corresponding author. Tel.: +82 42 868 8756; fax: +82 42 868 8362. E-mail address: bjyun@kaeri.re.kr (B.-J. Yun). the difficulties in experiments and measurements of the local phenomena. Recently, new experiments were carried out by some researchers to overcome these drawbacks of the existing database and then to develop advanced subcooled boiling models. Their experiments included the measurements of two-phase turbu- lent phenomena which has never been clarified in the past, and also the quantification of a propagation of local two-phase flow parameters along the test channel in the subcooled boiling flow. Roy et al. (1994, 1997) performed a subcooled boiling test in a vertical annulus test channel with Refrigerant-113 (R113). They applied some advanced instrumentations such as a two component laser Doppler velocimeter (LDV), a double optical fiber probe and a micro-thermocouple (TC) for the measurement of local two-phase flow parameters. From their test, a local void fraction, a bubble velocity, a liquid velocity, a liquid temperature and a wall temper- ature of a heater rod were obtained. One of the unique advantages of their work is that they provided turbulent information by mea- suring the 2-dimensional velocity fluctuation of both phases and the fluctuation of local liquid temperature up to the proximity of a heater rod wall. Yun (1996) and Yun et al. (2008) conducted subcooled boiling tests in various geometries such as a vertical annulus and sub- channels of 2 × 2 and 3 × 3 rod bundles under atmospheric pressure conditions. In the tests, a local void fraction a bubble velocity, a bub- 0029-5493/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.nucengdes.2010.02.004