Pressure Surge During Cryogenic Feedline Chilldown Process

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Gagan Agrawal ◽  
S. Sunil Kumar ◽  
Deepak Kumar Agarwal
Keyword(s):  
Numerical Study ◽  
Rocket Engine ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Flash Evaporation ◽  
Two Phase ◽  
Numerical Studies ◽  
Start Up ◽  
Flow Through ◽  
Pressure Surge

Cryogenic fluid entering a warm feedline absorbs heat and undergoes rapid flash evaporation leading to pressure surges, which can retard the flow inside the feedline. It may have serious repercussion in operation of the rocket engine during start up. Experimental and numerical studies are carried out to examine the effect of inlet pressure and initial feedline temperature on pressure surges. An analytical model using sinda/fluint software is developed to investigate this complex two-phase flow phenomenon including the various boiling regimes that exist during line chilling. The numerical study is carried out considering 1D flow through a cryogenic feedline of 2.47 m long and 0.01 m inner diameter with liquid nitrogen at 77.3 K as working fluid. Predictions are made for the inlet pressure in the range of 0.28–0.76 MPa and initial wall temperature of 200 K and 300 K. Subsequently, an experimental test rig is setup and the model is validated with the experimental data. The studies show that within the range of parameter considered, the magnitude of pressure surge increases exponentially with increase in inlet pressure and decreases with the prechilling of feedline.

Numerical study on two-phase flow through fractured porous media

2011 ◽  
Vol 54 (9) ◽  
pp. 2412-2420 ◽  
Author(s):  
ZhaoQin Huang ◽  
Jun Yao ◽  
YueYing Wang ◽  
Ke Tao
Keyword(s):  
Porous Media ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Fractured Porous Media ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through

scholarly journals HERMETIZATION OF VALVE SEALS FOR CRYOGENIC FLUIDS

2020 ◽  
Vol 6 (2) ◽  
pp. 12-19
Author(s):  
Yuri I. Kondrashov ◽  
Elena N. Ermilova ◽  
Anna N. Vidyaskina
Keyword(s):  
Mechanical Properties ◽  
Contact Pressure ◽  
Phase State ◽  
Working Fluid ◽  
Cryogenic Temperatures ◽  
Two Phase ◽  
Plastic Properties ◽  
Cryogenic Fluids ◽  
Specific Contact ◽  
Flow Through

For units providing flow control for cryogenic fluids and operating under conditions of a significant change in the temperature range from positive to cryogenic and in a two-phase state of the working fluid, the problem of sealing the closure members of the units (valve pairs) becomes urgent.Joint sealing is ensured by creating contact pressure in the joint through deforming the roughness peaks obtained by surface treatment of the valve pair.The mechanical properties of the materials of the contacting valve pairs change significantly under the influence of cryogenic temperatures. First of all, the plastic properties are reduced, therefore, the creation of increased contact pressure is required.The article presents a methodology for evaluation of changes in the microgeometry of contacting surfaces depending on the specific contact pressure. It also allows one to evaluate the conductivity of microgaps in the viscous and molecular regimes of fluid flow through contacting surfaces.

A Numerical Model of a Reciprocating-Mechanism Driven Heat Loop for Two-Phase High Heat Flux Cooling

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Olubunmi Popoola ◽  
Ayobami Bamgbade ◽  
Yiding Cao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Performance Optimization ◽  
Numerical Study ◽  
High Heat ◽  
Working Fluid ◽  
High Heat Flux ◽  
Two Phase ◽  
Transfer Device

An effective design option for a cooling system is to use a two-phase pumped cooling loop to simultaneously satisfy the temperature uniformity and high heat flux requirements. A reciprocating-mechanism driven heat loop (RMDHL) is a novel heat transfer device that could attain a high heat transfer rate through a reciprocating flow of the two-phase working fluid inside the heat transfer device. Although the device has been tested and validated experimentally, analytical or numerical study has not been undertaken to understand its working mechanism and provide guidance for the device design. The objective of this paper is to develop a numerical model for the RMDHL to predict its operational performance under different working conditions. The developed numerical model has been successfully validated by the existing experimental data and will provide a powerful tool for the design and performance optimization of future RMDHLs. The study also reveals that the maximum velocity in the flow occurs near the wall rather than at the center of the pipe, as in the case of unidirectional steady flow. This higher velocity near the wall may help to explain the enhanced heat transfer of an RMDHL.

Experimental Characterization of Two-Phase Flow Through Valves Applied to Liquid-Assisted Gas-Lift

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Renato P. Coutinho ◽  
Paulo J. Waltrich ◽  
Wesley C. Williams ◽  
Parviz Mehdizadeh ◽  
Stuart Scott ◽  
...  
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Experimental Characterization ◽  
Two Phase ◽  
Flow Through ◽  
Gas Lift

Abstract Liquid-assisted gas-lift (LAGL) is a recently developed concept to unload wells using a gas–liquid fluid mixture. The success deployment of the LAGL technology is related to the behavior of two-phase flow through gas-lift valves. For this reason, this work presents an experimental and numerical study on two-phase flow through orifice gas-lift valves used in liquid-assisted gas-lift unloading. To the knowledge of the authors, there is no investigation in the literature on experimental characterization of two-phase flow through gas-lift valves. Experimental data are presented for methane-water flow through gas-lift valves with different orifice port sizes: 12.7 and 17.5 mm. The experiments were performed for pressures ranging from 1.00 to 9.00 MPa, gas flow rates from 0 to 4.71 m3/h, and water flow rate from 0 to 0.68 m3/min. The experimental results are compared to numerical models published in the literature for two-phase flow through restrictions and to commercial multiphase flow simulators. It is observed that some models developed for two-phase flow through restrictions could successfully characterize two-phase flow thorough gas-lift valves with errors lower than 10%. However, it is first necessary to experimentally determine the discharge coefficient (CD) for each gas-lift valve. The commercial flow simulators showed a similar performance as the models available in the literature.

scholarly journals Comparison of different CFD software performances in the case of an incompressible air flow through a straight conical diffuser

2017 ◽  
Vol 21 (suppl. 3) ◽  
pp. 863-874
Author(s):  
Djordje Novkovic ◽  
Jela Burazer ◽  
Aleksandar Cocic
Keyword(s):  
Mathematical Modeling ◽  
Technological Development ◽  
Pulverized Coal ◽  
Thermal Engineering ◽  
Two Phase ◽  
Greenhouse Gases Emissions ◽  
Numerical Studies ◽  
Fluid Jets ◽  
History Of ◽  
Flow Through

Paper gives a review of the most important results of turbulence research achieved by the Laboratory for Thermal Engineering and Energy at the Vinca Insitute of Nuclear Sciences. Paper presents detailed overview of the history of the scientific research provided in the laboratory, from the beginning in the mid-60s to today, pointing out the main reasons initiating the investigations in this field. After the first period, which was mainly devoted to the research of the structure of the turbulence, since the beginning of the 80s, research is mainly oriented to the flows at high temperatures including chemical reactions and to the development and improvement of differential mathematical models as a modern and very efficient tool in the technological development. This research significantly contributed to the development of pulverized coal burners, plasma-chemical reactors, and optimization of pulverized coal fired boilers operating parameters and prediction of the greenhouse gases emissions. Most recent period includes experimental and numerical studies of the coherent structures in turbulent fluid jets, mathematical modeling of various turbulent thermal flow processes including two-phase turbulent flow in the multiphase heat exchangers and mathematical modeling of the atmospheric boundary layer.

Numerical Analysis of Combined VIV and Slug Flow in Time Domain

2016 ◽  
Author(s):  
Tor Huse Knudsen ◽  
Svein Sævik ◽  
Mats Jørgen Thorsen
Keyword(s):  
Multiphase Flow ◽  
Time Domain ◽  
Slug Flow ◽  
Structural Model ◽  
Numerical Study ◽  
Two Phase ◽  
Marine Risers ◽  
Numerical Studies ◽  
Vortex Induced Vibrations ◽  
Internal Velocity

Vortex induced vibrations (VIV) and slug flow are two important aspects for marine risers conveying a multiphase flow, and should be carefully examined due to the influence on the fatigue life of the structure. This article examines a truncated riser exposed to VIV with an internal two-phase slug flow. The main focus of the article was to examine the effect of internal slug flow on the VIV of a riser. The VIV were simulated in time domain with a linear structural model with constant pretension. Approximately 150 vortex shedding periods were simulated after the response reached steady state. An internal two-fluid flow was introduced, with constant internal velocity, pressure and uniform slug lengths. From the numerical study it was apparent that the slug velocity and slug length had an influence on the response pattern, amplitude and frequency. An analytical model that predicts additional response frequencies due to slug flow was also compared to the numerical studies. The analytical study produced similar additional response frequencies as the numerical study. The slug length and internal velocity can influence the response of the riser, and should be considered for marine risers conveying multiphase flow.

Experimental and numerical study on gas-solid two-phase flow through regulating valve of pulverized coal flow

2020 ◽  
Vol 155 ◽  
pp. 1-11 ◽  
Author(s):  
Meihua Chen ◽  
Haifeng Lu ◽  
Yong Jin ◽  
Xiaolei Guo ◽  
Xin Gong ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Numerical Study ◽  
Pulverized Coal ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Coal Flow

Investigation of Carbon Dioxide Explosive Boiling in Single Evaporator of a Two-Phase Mechanically-Pumped Thermal Control Loop

2010 ◽  
Author(s):  
Xi-Hui Sun ◽  
Zhen-Cheng Huang ◽  
Wen-Jia Xiao ◽  
Yue Chen ◽  
Zhen-Hui He ◽  
...  
Keyword(s):  
Reverse Flow ◽  
Thermal Control ◽  
Outer Ring ◽  
Working Fluid ◽  
Two Phase ◽  
Explosive Boiling ◽  
Start Up ◽  
Pressure Spike ◽  
Negative Effect ◽  
Set Up

We investigated experimentally the start-up characteristics of a mechanically pumped two-phase loop (MPTCL), with CO2 as working fluid, and a single evaporator that consists of a bent inner ring and an outer ring constructed by stainless tubes with hydraulic diameter of 2.6 mm and length of 9 m, along which totally 54 pieces of heating element are distributed. Experiments were performed in the following conditions: mass flow rates of 1.1, 2.1, and 3.3g/s; heat loads ranged from 50 to 300W, with the heat-load ratios of the inner ring to the outer ring 2.2:1, 1:1, and 1:2.2 at the operational temperature of −15°C, respectively. During the start-up cases, we detected a reverse flow accompanying with pressure spike, which can be understood as explosive boiling, and a subsequent temporal dry-out phenomenon at the outlet of the evaporator, as a result of explosive boiling. The back flow together with the pressure spike is helpful to set up a two-phase flow all along the evaporator, though it may have negative effect on the loop, especially, when coincident explosive boiling happens. However, such a pressure spike that depends on initial superheating should be controlled to avoid possible harm to the loop.

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