Flow Boiling in Vertical Down-Flow

Abstract

An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techx_iques _or predicting the onset of flow instability.

A critical review of predictive models for the onset of significant void in forced-convection subcooled boiling

“…The legends are indicated in Figure I and are identical for Figures I-9. It is shown that the model ofStaub (1_68) ( Figure 2) appears to be in good agreement with the data of Dougherty et al (1990), Whittle and Forgan (1967), Staub et al (1967), sad Ferrell (1964. These data reflect moderate and relatively high heat flux conditions.…”

“…where Y+ is the dimensionless distance from the wall to the top o/'th@bubble. Levy 1967 Dougherty, et al(1990) gives OFI data for vertical downwards flow in round tubes of six difl.erentdiameters. The OFI data were determined by a similar method as by Whittle and Forgan (1967).…”

Stability of forced-convection subcooled boiling in steady-state and transient annular flow

“…Lee and Bankoff [12] used calculations for symmetrical conditions between two flat plates to determine the empirical parameter Cs. By comparing their result with the hydraulic diameter concept with experimental data [7,21], obtained with circular tubes or rectangular channels, whose width and height were of similar magnitude.…”

“…Experimental evidence [7,9,21] indicates that OFI for a flow with a pressuredriven boundary condition occurs very close to OSV. Hence, the prediction of OFI in the present model becomes the problem of predicting OSV.…”

“…The comparison of the entire OFI model to the data of Whittle and Forgan [21] and Dougherty, et al [7] indicated that Cs might be correlated by the relation _._s Substituting equations (2), (3) and (5) into equation 1yields tt,e following solution for the critical detachment bubble radius…”