The effect of longitudinal spacer ribs on the minimum pressure drop in a heated annulus
Abstract
When evaluating a heated flow passage for vulnerability to static flow excursions, special note should be taken of flow restrictions which might allow premature vapor generation. In this study, measurements of steady state pressure drop were made for the downward flow of water in a vertical annulus. The outer wall was uniformly heated to allow subcooled boiling. Minima in the pressure drop characteristics were compared for test sections with and without longitudinal spacer ribs. For a given power and inlet temperature, the minimum occurred at a higher flow rate in the ribbed test section. This is attributed to vapor generation at the ribs. The work cited in this document shows how a restriction in a heated channel can produce vapor which would not be observed in the absence of the restriction. In the present study, the effect of a flow restriction on the tendency to flow excursion is explored by finding demand curves for a heated annulus in subcooled boiling flow. The annulus is heated from the outside, and alternately equipped with and without longitudinal spacer ribs. These ribs separate the heated and unheated walls; in pressing against the heated wall they provide a means for premature vapor production.
- Publication:
-
Presented at the ASME Winter Annual Meeting
- Pub Date:
- 1990
- Bibcode:
- 1990asme.meetR..25J
- Keywords:
-
- Annular Flow;
- Fluid Pressure;
- Pressure Reduction;
- Ribs (Supports);
- Spacers;
- Temperature Effects;
- Vaporizers;
- Annuli;
- Inlet Temperature;
- Pressure Effects;
- Pressure Measurement;
- Fluid Mechanics and Heat Transfer