Category: VIBRATION

Avoiding flow-induced vibration problems in shell-and-tube exchangers is an important task best accomplished at the design stage. Xist completes a screening analysis using mechanistic-based methods that have been validated with real cases and data. Because there are two types of vibration (tube and acoustic) and several excitation mechanisms, careful examination of...
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Intense sound and vibration can be produced by gas flow through a heat exchanger array of tubes. Typically, the oscillating pressure corresponds to a transverse standing wave across the heat exchanger shell that is perpendicular to the crossflow and the tube axes. The sound is attributed to flow-induced pressure pulsations that...
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Design software packages use incremental models to correlate the performance of heat exchanger geometry and fluid heat release curves; however, the heat exchanger thermal efficiency is often lost in the process. Thermal efficiency enables designers to select appropriate heat exchanger geometries with respect to heat release curves. It also helps them...
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Xist automatically generates a vibration analysis report for all cases. The software selects tube spans for analysis based on a range of factors, including TEMA shell type, baffle type and baffle orientation. While users are generally familiar with the structure of the vibration report for TEMA E shells, the methods applied...
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As heat exchanger design continues to evolve toward larger units with ever-increasing flowrates, the importance of tube vibration analysis has never been more important. However, u-tube designs can be particularly problematic. This webinar will discuss Xist assumptions with U-bends and when Xvib should be used for an accurate vibration analysis...
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This webinar describes the different types of error messages that Xist can generate. We focus on several important messages that are sometimes misunderstood or overlooked due to their frequency. These messages include warnings about a low B-stream, fluid property extrapolation, and fluidelastic instability. We describe their origins and the impact on...
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Xvib is an advanced tool for tube vibration study. This webinar discusses some specific aspects of Xvib inputs that can be adjusted for a more accurate vibration analysis....
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Component: Xist, Xvib Applicable to: All supported versions (versions 7.3 and 8) Date posted: 15 May 2018   TEMA H shells are commonly used as horizontal shellside reboilers. They can be baffled or nonbaffled as long as the unsupported span length remains within TEMA guidelines. In nonbaffled cases, the tubes have three...
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Component: Xist Applicable to: All supported versions (versions 7.3 and 8) Date posted: 4 November 2008 Last updated: 10 July 2019 Xvib models the vibration potential of a single tube using a rigorous finite element method. It is the most accurate tool available to estimate the potential for tube damage. Using...
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Component: Xist Applicable to: All supported versions (versions 7.3 and 8) Date posted: 4 May 2017   With high crossflow velocities and long tube spans, bundle entrance and exit regions can be susceptible to tube vibration. Anti-vibration support plates1 can be effective in these regions and can reduce tube vibration potential. At...
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Both the value and distribution of velocity along each span are important for proper assessment of tube vibration potential. Because of the disparity in spatial resolution between the small-scale finite element structural model of Xvib® and the larger scale incrementation scheme of Xist®, engineering judgment is required to populate the important...
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The challenges of a rules-based vibration screening in Xist® have often led to excessive conservatism for U-tubes positioned near the inlet nozzle. In this study, we simulated shellside diabatic flow over the U-bend portion of the bundle for a number of nozzle locations using computational fluid dynamics (CFD). Using the simulation...
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