Critical heat flux in forced convective subcooled boiling with a plane jet - (Effect of subcooling on CHF)

Critical heat flux (CHF) has been measured in a forced convective bailing with a plane jet on a rectangular heated surface of 40, 60, and 80 mm in length and 10 and 20 mm in width. Subcooled or saturated liquid is supplied through the plane jet with the thickness of 1 and 2 mm and covers the heated surface where vigorous boiling takes place. The experiment varies the jet velocity from 3 to 15 m/s, subcooling from 0 to 60 K, and system pressure is 0.1 MPa for water and 1.1 to 3 MPa for R22. It is found that the existing correlation for saturation can be applied to the CHF of water, but hardly to the CHF of R22 in spite of saturation condition. After the effects of jet velocity and subcooling on the CHF can be elucidated, a new correlation including the effect of subcooling is proposed to predict most of the CHF data within an accuracy of +/- 20 percent. This correlation for saturated condition is found to surprisingly agree with that theoretically derived by applying the Katto and Haramura criterion to this system.