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

Critical heat flux (CHF) during forced convective subcooled boiling with a plane jet has been yet made insufficient except for saturation condition when comparing CHF with impinging jet system including multiple jets. The present experiment has measured the CHF with plane jet on a rectangular heated surface of 40, 60, and 80 mm in length and 10 and 20 mm in width. Subcooled liquid being supplied through the plane jet with a different thickness of 1 and 2 mm, covers the heated surface where rigorous boiling takes place. The experiment varies a jet velocity from 3 to 15 m/s, a subcooling from 0 to 60 K, and system pressure at 0.1 MPa for water and at 1.5 to 3.0 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 interestingly agree with that theoretically derived by applying the Katto and Haramura criterion to this system.