Optimization analysis of structure parameters of steam ejector based on CFD and orthogonal test

Wu, Yifei; Zhao, Hongxia; Zhang, Cun-Quan; Wang, Lei; Han, Jisheng

doi:10.1016/j.energy.2018.03.041

Cited by 119 publications

(30 citation statements)

References 30 publications

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“…The NXP influenced both the entrainment ratio and critical back pressure. With the assumption of single-phase flow and ideal gas model, steam ejectors were optimized by Wu et al [27] combining the numerical simulation and orthogonal approaches including NXP, the diameters of the nozzle outlet, the mixing section, the diffuser, and the length of the constant area. They found that the outlet diameter of the primary nozzle is the most significant factor to influence the performances of the steam ejector.…”

Section: Introductionmentioning

confidence: 99%

Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

et al. 2019

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Supersonic ejectors are of great interest for various industries as they can improve the quality of the low-grade heat source in an eco-friendly and sustainable way. However, the impact of steam condensation on the supersonic ejector performances is not fully understood and is usually neglected by using the dry gas assumptions. The non-equilibrium condensation occurs during the expansion and mixing process and is tightly coupled with the high turbulence, oblique and expansion waves in supersonic flows. In this paper, we develop a wet steam model based on the computational fluid dynamics to understand the intricate feature of the steam condensation in the supersonic ejector. The numerical results show that the dry gas model exaggerates the expansion characteristics of the primary nozzle by 21.95%, which predicts the Mach number of 2.00 at the nozzle exit compared to 1.64 for the wet steam model. The dry gas model computes the static temperature lower to 196 K, whereas the wet steam model predicts the static temperature should above the triple point due to the phase change process. The liquid fraction can reach 7.2% of the total mass based on the prediction of the wet steam model. The performance analysis indicates that the dry gas model overestimates a higher entrainment ratio by 11.71% than the wet steam model for the steam ejector.

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Section: Introductionmentioning

confidence: 99%

Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

et al. 2019

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“…For the fiber-reinforced CPB, the analysis of orthogonal test results is shown in Table 3, where k i represents the average of all UCS fiber-reinforced under level i, and R j represents the range (the difference between the maximum and minimum average values) [41]. The significance indicates that the cement and solid mass concentration are still the most important factors affecting the UCS of CPB.…”

Section: Resultsmentioning

confidence: 99%

Fiber-Reinforced Cemented Paste Backfill: The Effect of Fiber on Strength Properties and Estimation of Strength Using Nonlinear Models

et al. 2020

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This experimental investigation was conducted to research the properties of polypropylene (PP) fiber-reinforced cemented paste backfill (CPB). The unconfined compressive strength (UCS) of the fiber-reinforced CPB showed a significant improvement with average UCS increase ratios of 141.07%, 57.62% and 63.17% at 3, 7 and 28 days, respectively. The macroscopic failure mode and SEM analysis indicated that fibers prevented the formation of large tensile and shear cracks during the pull-out and pull-off failure modes. A linear fitting function for the UCS at a curing time of 3 days and two polynomial fitting functions for the UCS at curing times of 7 and 28 days were established to characterize the relationship between the UCS of the fiber-reinforced and unreinforced CPB. Moreover, based on composite mechanics, nonlinear models related to the UCS and fiber reinforcement index were obtained. The estimated functions containing the fiber reinforcement index λ, which consists of the fiber content and aspect ratio of fiber, could evaluate the UCS. Furthermore, the fiber reinforcement index λ quantifies the enhancement by the fibers. Both estimation results indicated that the UCS values were estimated accurately at curing times of 3, 7 and 28 days in this study. Additionally, the estimation models could be used to guide the strength design of fiber-reinforced CPB. Besides this, the results showed that fiber-reinforced CPB can be used more widely in mine backfills and meets the requirements of controlled low-strength material (CLSM) for broader applications.

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“…To simplify the analysis, the ideal gas model is employed to investigate the fluid behavior inside the ejector and all thermo-physical properties are assumed to be constant except density, which is computed from the ideal gas equation. It was proved by researchers that that ideal gas model could provide similar results to a real gas model (Sriveerakul et al, 2007;Wu et al, 2018). Heat transfer through the walls is neglected because the fluid in the ejector has high speed.…”

Section: Cfd and Thermodynamic Model Numerical Proceduresmentioning

confidence: 99%

“…They evaluated the nozzle and the mixing section geometry and reported that the system efficiency increased 6%. Recently, Wu et al (2018) investigated effects of various geometrical parameters such as: NXP, the nozzle outlet diameter and the diameter of the contraction part of the mixing chamber on a steam ejector and concluded that these factors affect the performance of the ejector in term of entrainment ratio significantly.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of a Refrigeration Ejector: Effects of Environment-Friendly Refrigerants and Geometry of the Ejector Mixing Chamber

Moghaddam

Shafaee

Riazi

2019

European Journal of Sustainable Development Research

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In refrigeration cycles, ejectors are employed as thermo-compressors. To improve their performance, the operational conditions and geometrical parameters could be evaluated. In this numerical study firstly, the effects of refrigerants R1234ze(E) and R1234yf as replacements for R134a are investigated. Results showed that using R1234yf, the entrainment ratio and the coefficient of performance (COP) increase 10% and 1.7% respectively. When R1234ze is used, the entrainment ratio and the COP decrease 3.4% and 7% respectively compared with R134a. For the boiler operating temperature, an optimum value was found at which the entrainment ratio and the COP are maximum. However, the entrainment ratio and the COP enhance by increment of the evaporator temperature. In the second part, the effect of the mixing chamber convergence angle is studied. Results illuminated that by increment of the converging angle up to a certain value, the entrainment ratio and the COP enhance, but beyond the optimum angle, a reverse behavior is observed. However, by increment of the convergence angle, the critical back temperature declines continually. By increase of the convergence angle, the flow field inside the ejector is affected, and weaker shock waves are established at the end of mixing chamber that influence the critical back temperature.

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Optimization analysis of structure parameters of steam ejector based on CFD and orthogonal test

Cited by 119 publications

References 30 publications

Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

Fiber-Reinforced Cemented Paste Backfill: The Effect of Fiber on Strength Properties and Estimation of Strength Using Nonlinear Models

Numerical Investigation of a Refrigeration Ejector: Effects of Environment-Friendly Refrigerants and Geometry of the Ejector Mixing Chamber

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