Abstract
An analytical model to predict the influence of bubble formation on pressure drop in uniformly heated vertical channels, and on the resulting onset of flow instability has been developed and evaluated. The model is general in nature and covers the complete range of boiling regimes from single phase flow to fully saturated boiling, regardless of flow orientation. The pressure drop in the channel is determined by dividing the channel into regions of similar bubble behavior. The extent of each region is determined by the local fluid temperature. The theoretical results are compared to an extensive set of experimental data covering a range of channel diameters and operating conditions. Two different theoretical models for subcooled boiling fluid mass fraction are used, to gauge the influence of model selection on the accuracy. The model also predicts a threshold heat flux below which flow instability may not occur during flowrate reductions.
| Original language | English |
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| Pages (from-to) | 51-57 |
| Number of pages | 7 |
| Journal | American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD |
| Volume | 342 |
| State | Published - 1997 |
| Externally published | Yes |