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 wi th a plane jet has been yet made insufficient except for saturation co ndition when comparing CHF with impinging jet system including multipl e 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 w here rigorous boiling takes place. The experiment varies a jet velocit y from 3 to 15 m/s, a subcooling from 0 to 60 K, and system pressure a t 0.1 MPa for water and at 1.5 to 3.0 MPa for R22. It is found that th e existing correlation for saturation can be applied to the CHF of wat er, but hardly to the CHF of R22 in spite of saturation condition. Aft er the effects of jet velocity and subcooling on the CHF can be elucid ated, 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 agr ee with that theoretically derived by applying the Katto and Haramura criterion to this system.