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Y. Y. Hsu

Bio: Y. Y. Hsu is an academic researcher from Glenn Research Center. The author has contributed to research in topics: Subcooling & Boiling. The author has an hindex of 1, co-authored 1 publications receiving 757 citations.

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Y. Y. Hsu1
TL;DR: In this paper, the authors proposed a model to define the size range of active cavities as a function of wall temperature or heat flux, and showed that maximum and minimum sizes of effective cavities are functions of subcooling, pressure of the system, physical properties, and the thickness of the superheated liquid layer.
Abstract: The importance of surfare condition on nucleate boiling has long been recognized. It has also been known that only cavities of a narrow size range can be active nucleation sites. In order to define the size range of active cavities as a function of wall temperature or heat flux, a model is proposed. The model pictures a bubble nucleus at a site enveloped by a warm liquid. The nucleus will begin to grow into a bubble only when the surrounding liquid is sufficiently superheated. The time required for the liquid to attain this superheat is called the waiting period. The transfer of heat from the superheated liquid into the bubble is considered to be a transient conduction process. A cavity is considered effective only if the waiting period is finite. This criterion gives the limiting sizes of effective cavities. The equations show that maximum and minimum sizes of effective cavities are functions of subcooling, pressure of the system, physical properties, and the thickness of the superheated liquid layer. Comparison of theoretical prediction with experimental data from several sources was made. The fluids considered were ether, pentane, and water, with water under various degrees of subcooling. The theory did predict the incipience of boiling and size range of cavities successfully.

832 citations


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Book
01 Jan 1981

2,237 citations

Journal ArticleDOI
TL;DR: The high surface tension forces offered by liquids in nanowire arrays made of Si and Cu can be exploited to increase both the critical heat flux (CHF) and the heat transfer coefficient (HTC) by more than 100%.
Abstract: Boiling is a common mechanism for liquid-vapor phase transition and is widely exploited in power generation and refrigeration devices and systems. The efficacy of boiling heat transfer is characterized by two parameters: (a) heat transfer coefficient (HTC) or the thermal conductance; (b) the critical heat flux (CHF) limit that demarcates the transition from high HTC to very low HTC. While increasing the CHF and the HTC has significant impact on system-level energy efficiency, safety, and cost, their values for water and other heat transfer fluids have essentially remained unchanged for many decades. Here we report that the high surface tension forces offered by liquids in nanowire arrays made of Si and Cu can be exploited to increase both the CHF and the HTC by more than 100%.

623 citations

Journal ArticleDOI
TL;DR: In this paper, a review examines recent advances made in predicting boiling heat fluxes, including some key results from the past, including nucleate boiling, maximum heat flux, transition boiling, and film boiling.
Abstract: ▪ Abstract This review examines recent advances made in predicting boiling heat fluxes, including some key results from the past. The topics covered are nucleate boiling, maximum heat flux, transition boiling, and film boiling. The review focuses on pool boiling of pure liquids, but flow boiling is also discussed briefly.

575 citations

Journal ArticleDOI
TL;DR: In this article, a review of the nucleation of bubbles in solutions supersaturated with a gas, in particular the bubble nucleation that occurs at specific sites, as a cycle is presented.

534 citations

Journal ArticleDOI
TL;DR: In this article, aqueous-based nanofluids containing γ-alumina nanoparticles (primary particle size 10-50 nm) were used to investigate their heat transfer behavior under nucleate pool boiling conditions.
Abstract: This paper is concerned about pool boiling heat transfer using nanofluids, a subject of several investigations over the past few years. The work is motivated by the controversial results reported in the literature and the potential impact of nanofluids on heat transfer intensification. Systematic experiments are carried out to formulate stable aqueous based nanofluids containing γ-alumina nanoparticles (primary particle size 10–50 nm), and to investigate their heat transfer behaviour under nucleate pool boiling conditions. The results show that alumina nanofluids can significantly enhance boiling heat transfer. The enhancement increases with increasing particle concentration and reaches ∼ ∼40% at a particle loading of 1.25% by weight. Discussion of the results suggests that the reported controversies in the thermal performance of nanofluids under the nucleate pool boiling conditions be associated with the properties and behaviour of the nanofluids and boiling surface, as well as their interactions.

468 citations