Master's Theses

Date of Award

2011

Document Type

Thesis

Department

Mechanical Engineering

Keywords

Aqueous Solutions, Critical heat flux, pressure

Abstract

"Pool boiling experiments have been conducted with self-rewetting fluids consisting of aqueous butanol and pentanol solution to study the boiling heat transfer enhancement at pressures of 1 ~ 4 bars. Although self-rewetting fluids have been used to enhance the performance of heat pipes, boiling heat transfer characteristics are yet to be fully understood especially at pressures above atmospheric. Pool boiling experiments with aqueous butanol and pentanol solutions were performed using an electrically heated platinum wire to obtain pool boiling heat transfer data up to the Critical Heat Flux (CHF). Aqueous solutions with butanol concentrations 2-7% showed enhanced heat transfer coefficients and CHF data at various pressure levels. Pentanol aqueous solutions were also tested on the heated wire to observe the consistency for reduce in size of the nucleated bubbles. In comparison to water, butanol aqueous solutions showed 20-270% higher values of CHF at pressures up to 4 bars. The bubble sizes were also observed to be significantly smaller in self-rewetting fluids compared to those in water at the same pressure. This observation was consistent even at higher pressures. However, for higher concentrations (i.e. butanol 5% and 7%), the CHF enhancement was diminished at higher pressures."

 
 

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