Influence of Heater Orientation on Fluctuations in Steady-state Nucleate Boiling
In observations of steady-state nucleate boiling, fluctuations in the temperature and heat flux might initially appear to be completely random. However, it was shown that, for a vertically mounted platinum wire in liquid nitrogen, the fluctuations about the steady-state exhibit an average counterclo...
| Main Author: | |
|---|---|
| Format: | Others |
| Published: |
PDXScholar
1995
|
| Subjects: | |
| Online Access: | https://pdxscholar.library.pdx.edu/open_access_etds/4958 https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=6030&context=open_access_etds |
| Summary: | In observations of steady-state nucleate boiling, fluctuations in the temperature and heat flux might initially appear to be completely random. However, it was shown that, for a vertically mounted platinum wire in liquid nitrogen, the fluctuations about the steady-state exhibit an average counterclockwise circulation when the heat flux is plotted versus the superheat temperature. An area associated with the average circulation was proposed as a numerical measure of stability for steady-state nucleate boiling. The mechanisms for the generation of these fluctuations are thought to be the feedback of the bubbles rising past the wire and the differential heating and cooling that this engenders. Data similar to the data on the vertical wire have been obtained using the same wire mounted horizontally. Although the counterclockwise circulation mentioned above is still seen, the measure of stability as proposed earlier, is less useful for prediction of the transition to film boiling. This reduced sensitivity can be attributed to the fact that the possibility of feedback through the rising bubbles has been eliminated. |
|---|