Numerical modeling of supercritical carbon dioxide flow in see-through labyrinth seals

Yuan, Hongyong; Pidaparti, Sandeep; Wolf, Mathew; Edlebeck, John; Anderson, Mark

doi:10.1016/j.nucengdes.2015.08.016

Cited by 30 publications

(23 citation statements)

References 16 publications

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“…They concluded that the pressure drop of PCHE with S-shaped fins is 4-5 times lower than that of PCHE with zig-zag channels but at the same time Nusselt number is 24-34% lower depending on the Reynolds number. Ngo et al [15] extended the range of operating parameters for both the PCHEs tested by Nikitin et al [14] to study the influence of Prandtl number variation on their thermal-hydraulic performance. They used integral form of log-mean temperature difference (LMTD) to calculate the overall heat transfer coefficients since the operating conditions are closer to the critical point where specific heat varies drastically with the temperature.…”

Section: Pche Testing and Modeling Work At Tokyo Institute Of Technologymentioning

confidence: 99%

Fundamental study of key issues related to advanced sCO<sub>2</sub> Brayton cycle: Prototypic HX development and cavitation

Ranjan

2018

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Chapter 1 Compact discontinuous fin style diffusion bonded heat exchangers for the sCO 2 Brayton cycles Abstract Diffusion bonded heat exchangers are the leading candidates for the sCO 2 Brayton cycles in next generation nuclear power plants. Commercially available diffusion bonded heat exchangers utilize set of continuous semi-circular zigzag micro channels to increase the heat transfer area and enhance heat transfer through increased turbulence production. Such heat exchangers can lead to excessive pressure drop as well as flow maldistribution in the case of poorly designed flow distribution headers. The goal of the current project is to fabricate and test potential discontinuous fin patterns for diffusion bonded heat exchangers; which can achieve desired thermal performance at lower pressure drops. Prototypic discontinuous offset rectangular and Airfoil fin surface geometries were chemically etched on to 316 stainless steel plate and sealed against an un-etched flat pate using O-ring seal emulating diffusion bonded heat exchangers. Thermal-hydraulic performance of these prototypic discontinuous fin geometries was experimentally evaluated and compared to the existing data for the continuous zigzag channels. The data generated from this project will serve as the database for future testing and validation of numerical models. Re High zigzag Medium zigzag Low zigzag Desgined rectangular Offset fins Chapter 4 Techno-economic analysis of heat rejection options for the sCO 2 Brayton cycles Abstract Techno-economic feasibility of dry air cooling the supercritical carbon dioxide (S-CO 2) Brayton cycle has been investigated. A radiator type CO 2-to-air heat exchanger has been identified in the current market in an attempt to reduce the capital cost of the power plant. A quotation for the same is obtained and the heat exchanger was modeled in engineering equation solver (EES) to confirm the quoted heat exchanger performance and sizing. A cost-based optimization procedure was employed to identify the cycle optimum operating conditions with the goal of minimizing the plant capital cost per unit electrical output ($/kWe) for the Advanced Fast reactor (AFR) with 250 MW th heat input. Cycle operating conditions such as minimum temperature, minimum pressure, and maximum pressure are chosen as the parameters to be optimized. Minimum pressure and minimum temperature are selected to be in the vicinity of pseudo-critical line to take advantage of the high fluid density near the pseudo-critical point while an increasing minimum CO 2 temperature is dictated by the ambient air temperature. The cycle maximum pressure is varied from 18 to 30 MPa. The mechanical design of the cycle heat exchangers (reactor intermediate sodium-to-CO 2 heat exchanger, high temperature recuperator, and the low temperature recuperator) and the piping are modified as per ASME code requirements to withstand the higher cycle design pressures. The associated change in the cost of components is also taken into account. All the calculations are performed using th...

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Section: Pche Testing and Modeling Work At Tokyo Institute Of Technologymentioning

confidence: 99%

Fundamental study of key issues related to advanced sCO<sub>2</sub> Brayton cycle: Prototypic HX development and cavitation

Ranjan

2018

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“…The results of the experimental research and the CFD calculations of the flow in a straight-through labyrinth seal are included in Yuan et al (2015). The CFD calculations were carried out within the framework of OpenFOAM.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Gas Flow in a Labyrinth Seal of Variable Pitch

Joachimmiak

Krzyślak

2019

JAFM

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The paper discusses the results of investigations performed for the segments of straight-through labyrinth seals of constant length. Increasing the number of teeth of a segment resulted in a reduction of the pitch length to obtain the slot seals. The phenomena occurring during gas flow in labyrinth and slot seals differ significantly. They are described with different calculation models. The analysis presented in this paper is related to the change of the tightness and the nature of the flow from a straight-through labyrinth seal to a slot seal. The paper includes the results of experimental research and CFD calculations. Models applied for the Neumann and Scharer labyrinth seals as well as the model of the Salzman and Fravi slot seals were discussed. For the Neumann and Scharer models, correction coefficients for the tested geometry were proposed. Based on the assumptions for the said models and the obtained results, the phenomena responsible for the minimization of the leakage were discussed. The leakage rate in segments of different gap heights depending on the number of teeth and the pressure ratio upstream and downstream of the segment has been analyzed. Based on the experimental data, an optimum number of teeth in the segment for minimum leakage was determined. CFD calculations allowed determining the minimum leakage geometry. The experimental data contained in this paper confirm that the determined optimum pitch range is independent of the pressure drop.

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“…Pugachev et al [21,22] used a CFD model to research the direction of the main vortex in a short chamber with a backward-facing step and numerically and experimentally verified that the segmentation negatively affects the leakage performance and stiffness coefficients of the brush-labyrinth sealing configuration. Yuan et al [23] established a CFD model to optimize the seal design for supercritical carbon dioxide in turbomachinery, and the model was then confirmed based on the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Effects of Structural Parameters of Labyrinth Cavity on Sealing Performance

Feng

Wang

Yang

et al. 2018

Mathematical Problems in Engineering

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This paper presents a study on the leakage characteristics of a labyrinth piston compressor. A computational fluid dynamics model was applied to predict the effects of different structural parameters of the labyrinth seal on the sealing performance. The velocity field through the sealing clearance and labyrinth cavity was demonstrated and analyzed. An experimental rig was built to validate the simulation model, and the results of the simulation and experimental data showed a good agreement. The effects of the cavity width, cavity depth, tooth thickness, and clearance of the seal on the leakage characteristics were discussed in detail. The results showed that, except for the significant influence of the labyrinth clearance, / (the ratio of cavity depth to labyrinth clearance) should be bigger than 2.7 to achieve the minimum leakage flow, and the effect of the varied cavity width can be ignored. Moreover, when the piston length and cavity width remain constant, the thinner the tooth thickness, the greater the number of labyrinth cavities that can be arranged, and the higher the sealing performance achieved.

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Numerical modeling of supercritical carbon dioxide flow in see-through labyrinth seals

Cited by 30 publications

References 16 publications

Fundamental study of key issues related to advanced sCO<sub>2</sub> Brayton cycle: Prototypic HX development and cavitation

Fundamental study of key issues related to advanced sCO<sub>2</sub> Brayton cycle: Prototypic HX development and cavitation

Analysis of the Gas Flow in a Labyrinth Seal of Variable Pitch

Numerical Investigation on the Effects of Structural Parameters of Labyrinth Cavity on Sealing Performance

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