Effect of inclination on pressure drop and flow regimes in large flattened-tube steam condensers

This thesis presents an experimental study of the inclination effect on pressure drop and flow regime during condensation of steam in a large flattened tube used in air-cooled condensers (ACC) for power plants. Steam with mass flux of about 7 kg m-2 s-1 was condensed inside a 10.7 m long, flattened test tube with inclination angle varied from horizontal up to 70o. The original full-sized steel tube was cut in half along the centerline, and the removed part was replaced by a polycarbonate window to enable simultaneous flow visualization in situ with heat transfer and pressure drop measurements. A uniform velocity profile of 2.03 ± 0.12 m s-1 was imposed on the air side to extract heat from the steam in a cross flow direction. The experimental results showed that increasing the inclination angle led to reductions of pressure drop due to the improvement in the gravity-assisted drainage of condensate inside the test tube. At such low mass fluxes, tube inclination significantly influenced the flow pattern which was observed to be a well separated stratified flow throughout the tube at all inclination angles for downward flow. Because of the creation of the visualization window, the tube width was less than that used in industry, and thus a model that accounts for the differences in tube geometry between the full and test tube was developed and used to convert experimental pressure drop results to the full-sized tube under the same operating conditions. A prediction of pressure drop performance of the same steam condensing system under vacuum condition was also discussed. The negative dependence of pressure drop on inclination angle also prevailed in both converted results in atmospheric condition and the predicted ones in vacuum condition.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2017

Author dc:creator

• Kang, Yu

Contributors dc:contributor

• Hrnjak, Predrag Stojan

• air-cooled condenser
• inclination
• pressure drop
• condensation
• flattened tube

Statement dc:rights

• Copyright 2016 Yu Kang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/95329

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/95329