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Subcooling
About: Subcooling is a research topic. Over the lifetime, 6150 publications have been published within this topic receiving 99125 citations.
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TL;DR: In this article, the effects of spray nozzle, volumetric flux, subcooling and working fluid were investigated for nucleate boiling heat transfer and critical heat flux for full cone sprays.
304 citations
TL;DR: In this paper, a correlation for predicting the wall superheat and wall heat flux at ONB has been developed from the data obtained in this study and that reported in the literature.
Abstract: The partitioning of the heat flux supplied at the wall is one of the key issues that needs to be resolved if one is to model subcooled flow boiling accurately. The first step in studying wall heat flux partitioning is to account for the various heat transfer mechanisms involved and to know the location at which the onset of nucleate boiling (ONB) occurs. Active nucleation site density data is required to account for the energy carried away by the bubbles departing from the wall. Subcooled flow boiling experiments were conducted using a flat plate copper surface and a nine-rod (zircalloy-4) bundle. The location of ONB during the experiments was determined from visual observations as well as from the thermocouple output. From the data obtained it is found that the heat flux and wall superheat required for inception are dependent on flow rate, liquid subcooling, and contact angle. The existing correlations for ONB underpredict the wall superheat at ONB in most cases. A correlation for predicting the wall superheat and wall heat flux at ONB has been developed from the data obtained in this study and that reported in the literature. Experimental data are within630 percent of that predicted from the correlation. Active nucleation site density was determined by manually counting the individual sites in pictures obtained using a CCD camera. Correlations for nucleation site density, which are independent of flow rate and liquid subcooling, but dependent on contact angle have been developed for two ranges of wall superheat—one below 15°C and another above 15°C. @DOI: 10.1115/1.1471522#
300 citations
TL;DR: In this paper, a heat transfer controlled bubble model has yielded three semi-empirical correlations to predict bubble-growth rate, maximum bubble diameter and maximum bubble growth time for the subcooled nucleate flow boiling of water.
298 citations
TL;DR: In this paper, a wall-boiling model is implemented based on a wall heat flux partition algorithm, which is able to calculate the cross sectional averaged vapour volume fraction of vertical heated tubes tests with good agreement to published experimental data.
271 citations
TL;DR: In this paper, the effect of volumetric flux distribution on critical heat flux (CHF) on spray cooling of a hot surface was investigated, and it was determined that CHF can be maximized when the spray is configured such that the spray impact area just inscribes the square surface of the heater.
Abstract: Spray cooling of a hot surface was investigated to ascertain the effect of nozzle-to-surface distance on critical heat flux (CHF). Full cone sprays of Fluorinert FC-72 and FC-87 were used to cool a 12.7 X 12.7 mm 2 surface. A theoretical model was constructed that accurately predicts the spray's volumetric flux (liquid volume per unit area per unit time) distribution across the heater surface. Several experimental spray sampling techniques were devised to validate this model. The impact of volumetric flux distribution on CHF was investigated experimentally. By measuring CHFfor the same nozzle flow rate at different nozzle-to-surface distances, it was determined CHF can be maximized when the spray is configured such that the spray impact area just inscribes the square surface of the heater. Using this optimum configuration, CHF data were measured over broad ranges of flow rate and subcooling, resulting in a new correlation for spray cooling of small surfaces.
267 citations