Mist/steam cooling in a 180{degree} tube bend
An experimental study on mist/steam cooling in a highly heated, horizontal 180{degree} tube bend has been performed. The mist/steam mixture is obtained by blending fine water droplets (3{approximately}15 microns) with the saturated steam at 1.5 bar. The test section consists of a thin wall ({approximately}0.9 mm), welded, circular, stainless steel 180-degree tube (20 mm ID) with a straight section downstream of the curved section, and is heated directly by a DC power supply. The experiment was conducted with steam Reynolds numbers ranging from 10,000 to 35,000, wall superheat up to 300 C, and droplet to steam mass ratio at about 2%. The results show that the heat transfer performance of steam can be significantly improved by adding mist into the main flow. Due to the effect of centrifugal force, the outer wall of the test section always exhibits a higher heat transfer enhancement than the inner wall. The highest enhancement occurs at a location on the outer wall about 45{degree} downstream of the inlet of the test section. Generally, only a small number of droplets can survive the 180{degree} turn and be present in the downstream straight section, as observed by a Phase Doppler Particle Analyzer (PDPA) system. The overall cooling enhancement of the mist/steam flow ranges from 40% to 300%. It increases as the main steam flow increases, but decreases as the wall heat flux increases.
- Research Organization:
- Clemson Univ., SC (US)
- OSTI ID:
- 20002469
- Report Number(s):
- CONF-990805--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mist/steam cooling in a heated horizontal tube -- Part 2: Results and modeling
Theoretical and experimental investigation of mist cooling of a heated plate