Experimental comparison of the rewet phenomenom in transient and stable film boiling flows

McCord, Michelle Lauren

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https://hdl.handle.net/2142/115792 Copy

Description

Title

Experimental comparison of the rewet phenomenom in transient and stable film boiling flows

Author(s)

McCord, Michelle Lauren

Issue Date

2022-04-28

Director of Research (if dissertation) or Advisor (if thesis)

Brooks, Caleb

Committee Member(s)

Kozlowski, Tomasz

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Boiling
• Post-CHF
• Heat Transfer

Abstract

An experimental dataset has been collected for vertical boiling flow in a square channel to investigate the film boiling phase following critical heat flux (CHF) in subcooled conditions. The experimental data explores a combination of atmospheric and low pressure scenarios with varying flow rate and subcooling. The conditions are a combination of transient and stable film boiling scenarios at 5 ◦C and 15 ◦C subcooled and mass flux values of 93.7 kg/m2-s and 187.4 kg/m2-s. For transient conditions, the power to the heated surface is shut off at the moment CHF is reached, allowing a cooling excursion through the transition regime, film boiling, and return to nucleate boiling. In the stability cases, the power supply to the heated surface is lowered in small increments throughout the film boiling region. This results in a full film development at stable points as the power level is stepped down until the rewet excursion is observed. The boiling curve and other system parameters for each condition are presented along with the conditions at which rewet back to nucleate boiling occurs. The study reveals the differences between transient and stable film boiling scenarios as an impact on the rewet conditions. Stable film boiling scenarios are found to rewet at a lower temperature than in a transient case. In addition, an increase in the flow rate or an increase in the subcooling of the system both correlate with an increase in the heat flux at rewet. Further investigation utilizes high-speed imaging to characterize the flow patterns along the full development of film boiling and the rewet phenomena described within each system condition.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Michelle McCord

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