Tag: BOILING

This webinar reviews HTRI and literature boiling data outside low-finned tubes, compares HTRI flow boiling data across plan and low-finned tube bundles, examines and evaluates HTRI’s current boiling model, and describe a more simple and more accurate boiling model....
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This webinar will discuss flow boiling data across ideal plain tube bundles collected in the HTRI Multipurpose Boiling Unit and compiled from the literature. Our current method has four heat transfer mechanisms: nucleate boiling, convective boiling, thin liquid film conduction, and natural convection. It is complex with many correlation parameters and...
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Engineers may design flat bundles in kettle reboilers by removing tuberows from round bundles to create a larger disengagement space. This webinar discusses application of the kettle reboiler circulation boiling model to flat bundles. It reviews calculations for the static driving head and maximum heat flux for flat bundles. We also...
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Over the past several decades, the accuracy and usability of computational methods have substantially improved. This report reviews the complicated physics of two-phase flow and phase change, presents the equations of motion for a two-phase flow with various closure models, and compares current computational approaches. Although inadequate for the entire spectrum of...
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Vertical shellside boiling is used for a variety of applications, including vertical thermosiphon reboilers where hot fluid must be on the tubeside steam generators/waste heat boilers, which use very hot or corrosive fluids as the heating medium vertical feed-effluent exchangers, whose vertical orientation prevents phase separation Ideal vertical shellside reboilers have...
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Flow boiling prediction methods were recently improved using data collected from ideal crossflow bundles. When applied with accurate property models, these modified methods also improve prediction of X‑shell and kettle reboiler heat transfer measurements. Future implementation of the modified methods in Xchanger Suite should improve the accuracy of flow boiling predictions;...
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This report reviews literature and HTRI kettle reboiler data obtained when the liquid level was below the top of the tube bundle. We propose both a method to predict the two-phase jet height above the liquid level and an algorithm for predicting the heat transfer coefficient above the liquid level....
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This report discusses liquid-phase and flow boiling data collected on the shell side of a horizontal, nonbaffled plain tube bundle. Using these and other HTRI data, we evaluated heat transfer predictions from HTRI Xchanger Suite 7.3 and modified our methods. Fluid temperature measurements around the bundle demonstrate thermal stratification of liquid...
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HTRI conducted liquid-phase and phase-change experiments in a welded plate heat exchanger (WPHE) provided by Hisaka Works, Ltd. With the test plate pack installed vertically, cold fluid flowed horizontally, and steam condensed downward. We conducted single-phase and boiling tests using p-xylene as the test fluid, as well as boiling tests using...
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HTRI collected flow boiling data using a plate-and-shell heat exchanger (PSHE) provided by Vahterus Oy. In the exchanger, steam condensed on the plate side, and process fluids—pure n-pentane and a mixture of n-pentane and p-xylene—boiled on the shell side. This report discusses the data and analysis, including evaluations using Xphe® 7.3.1....
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This report reviews boiling correlations based on reduced pressure and used in Xchanger Suite 8.0. Alternative, more theoretical correlations using physical properties instead of reduced pressure are discussed. ...
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HTRI has collected flow boiling data in a plate-and-frame heat exchanger, as well as in two plate-and-shell heat exchangers and one welded plate heat exchanger. Based on these data, we have developed an improved flow boiling method applicable to heat exchangers using corrugated plates....
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This report provides a comprehensive look at the turndown operation of a vertical tubeside thermosiphon reboiler (VTTR), including predictions of thermal and hydraulic performance and quantitative criteria for turndown limits. Data were collected for water, n-pentane, p-xylene, and n-pentane/p-xylene mixtures in an industrially relevant VTTR flow loop. The unit was systematically turned...
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This report summarizes HTRI data on vertical tubeside boiling, highlighting the shortcomings of current methods in accurately predicting tubeside pressure drop and heat transfer at low mass velocities. Improvements to the liquid holdup model and a warning message for thermal prediction close to turndown conditions are also discussed. When implemented in...
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This report provides an overview of several mechanisms for the breakdown of falling film. Available literature and HTRI data enable confirmation of the minimum wetting flow rate calculation used in Xist 8.2 and the development of two correlations for determining Reynolds numbers for the Marangoni breakdown, one for the subcooled zone...
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Recirculation in kettle reboilers causes a boiling temperature increase or rise for mixtures because it increases the concentration of less volatile components of the bundle flow. Methods in Xist® 9.0 account for this rise at the top of the bundle. However, the bubble point calculation is based on the feed composition...
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