Experiments on subcooled flow boiling heat transfer in a vertical annular channel

Experiments on subcooled flow boiling heat transfer are carried out in a vertical annular channel the inner wall of which is heated and the outer wall insulated. Refrigerant-113 is the working fluid. Flow boiling heat transfer data are reported at three mass velocities (579, 801 and 1102 kg m-2 s-1), three pressures (312, 277 and 243 kPa), and three inlet subcoolings (20.0, 30.0 and 36.50C). A multiple-hysteresis phenomenon is identified. The measured wall heat transfer coefficients are compared with predictions by various correlations and an improvement of the Shah correlation for annuli is suggested. (author)