scholarly journals Experiments on supercritical flow instability in two vertical parallel channels

2020 ◽  
Author(s):  
Inderjit Singh ◽  
Vijay Chatoorgoon
Keyword(s):  
Flow Instability ◽  
Supercritical Flow ◽  
Parallel Channels

Modeling and analysis of supercritical flow instability in parallel channels

2013 ◽  
Vol 57 (2) ◽  
pp. 549-557 ◽  
Author(s):  
Ting Xiong ◽  
Xiao Yan ◽  
Shanfang Huang ◽  
Junchong Yu ◽  
Yanping Huang
Keyword(s):  
Flow Instability ◽  
Supercritical Flow ◽  
Modeling And Analysis ◽  
Parallel Channels

Experimental Investigation of Flow Instability Between Two Vertical Parallel Channels Using Supercritical CO2

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Anantvir Singh Saini ◽  
Vijay Chatoorgoon ◽  
Dhanashree S. Ghadge
Keyword(s):  
Flow Instability ◽  
Working Fluid ◽  
Parallel Channel ◽  
Outlet Channel ◽  
Supercritical Flow ◽  
University Of Manitoba ◽  
Parallel Channels ◽  
Channel Assembly ◽  
Flow Experiments ◽  
Insight Into

Abstract Supercritical flow experiments were conducted at University of Manitoba using supercritical flow facility-vertical (SFF-V), which is a two vertical parallel channel assembly. The working fluid was CO2 at supercritical pressure and was driven by natural convective forces rather than a pump. Different system pressures (7.4 MPa–9.1 MPa), inlet temperatures (7 °C–30.1 °C) and various outlet-channel k-factors were used. A total of eleven parallel channel out-of-phase instability boundary points were obtained and the details of those cases are reported herein. These results can be used for code validation, to enrich the limited database of supercritical parallel-channel instability and to lend further insight into supercritical flow instability in heated parallel channels.

Supercritical Flow Stability in Two Parallel Channels

2006 ◽  
Author(s):  
Vijay Chatoorgoon
Keyword(s):  
Analytical Study ◽  
Two Phase Flow ◽  
Flow Instability ◽  
Flow Stability ◽  
Phase Flow ◽  
Two Phase ◽  
Supercritical Flow ◽  
Light Water ◽  
Parallel Channels

An analytical study of supercritical flow stability in two parallel channels is reported here. This would be of immense value to new reactor designs that propose to use supercritical light water on the primary side. The finding is that two-phase flow instability and supercritical flow instability are not identical, as there are notable phenomenological differences as well as mathematical differences.

Flow Instability Investigation at Supercritical Pressures in Parallel Channels by Computational Fluid Dynamics Adopting Low- and High-Power Boundaries

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Edward Shitsi ◽  
Seth Kofi Debrah ◽  
Vincent Yao Agbodemegbe ◽  
Emmanuel Ampomah-Amoako
Keyword(s):  
Flow Instability ◽  
Oscillation Amplitude ◽  
Lower Threshold ◽  
Inlet Temperature ◽  
Parallel Channel ◽  
Flow Oscillation ◽  
Channel System ◽  
Numerical Studies ◽  
Mass Flowrate ◽  
Parallel Channels

Abstract Supercritical water-cooled reactor (SCWR), which is considered as the logical extension of existing light water reactors (LWRs) (pressurized water reactor and boiling water reactor (BWR)), has the potential of increasing the efficiency of power generation to 45% compared to 33% of that of LWRs. But without the challenges of heat transfer and hydrodynamics, and reactor core design materials due to supercritical flow instability which is associated with sharp variation in fluid properties near the vicinity of the pseudo-critical temperature. Supercritical flow instability therefore needs to be addressed ahead of the deployment and operation of SCWR in the near future. The main purpose of this study is to carry out flow instability analysis in parallel channels with supercritical water. The study also aims at examining the capability of using three-dimensional (3D) simulation of turbulent flow in arbitrary regions computational continuum mechanics C++ based code (3D STAR-CCM+ CFD code) to predict flow oscillation amplitude and periods, and instability power boundaries at low-power boundary (LPB) and at high-power boundary (HPB). Parameters considered in the investigation include mass flowrate, system pressure, and gravity. Two different threshold power instability boundaries were obtained from the study. These instability power boundaries include lower threshold where stability of the parallel channel system decreases with increasing coolant inlet temperature, and upper threshold where stability of the parallel channel system increases with increasing coolant inlet temperature. From the results of the investigation, it can be found that: (1) for LPB at 23 MPa, only lower threshold was obtained as flow instability power boundary; and for HPB at 23 MPa, both lower and upper thresholds were obtained as flow instability power boundaries. The numerical findings quite well agree with the experimental findings at 23 MPa for both LPB and HPB; (2) only lower threshold was obtained as flow instability power boundary at both 23 MPa and 25 MPa for LPB. For HPB, both lower and upper thresholds were obtained as flow instability power boundaries at both 23 MPa and 25 MPa; (3) only lower threshold was obtained as flow instability power boundary for the parallel channel system with or without gravity influence for LPB. For HPB, both lower and upper threshold flow instability power boundaries were obtained for the parallel channel system with gravity influence, but only lower threshold flow instability power boundary was obtained for system without gravity influence; (4) only lower threshold was obtained as flow instability power boundary at system mass flowrates of 125 kg/h and 145 kg/h for LPB. For HPB, both lower and upper threshold flow instability power boundaries were obtained for system mass flowrate of 125 kg/h, but only lower threshold flow instability power boundary was obtained for system mass flowrate of 145 kg/h. For both LPB and HPB, the numerical findings agree quite well with the experimental results for a system operated at 125 kg/h and 145 kg/h; (5) the investigated parameters such as mass flowrate, pressure, and gravity have significant effects on amplitude of mass flow oscillation, but have little effects on the period of mass flow oscillation for both LPB and HPB. Results from the numerical simulation were compared with the results from the experiment for both LPB and HPB. The numerical amplitude results obtained were far less than the amplitude results obtained from the experiment. But there was no significant difference between the oscillation periods obtained from both the numerical simulation and experiment. (6) Flow instability studies including predicting flow oscillation amplitude and periods, and instability power boundaries could be carried out using 3D STAR-CCM+ CFD code. The effects of heating structures on flow instability results have not been considered in this study. Previous studies have shown that including heating structures in geometrical models for numerical studies may have effects on flow instability results. More experimental studies are needed for validation of similar numerical studies carried out at supercritical pressures using various numerical tools.

The Influence of Non-Uniform Heating on Two-Phase Flow Instability in Parallel Channels

2013 ◽  
Author(s):  
Xiaodong Lu ◽  
Linglan Zhou ◽  
Hong Zhang ◽  
Yingwei Wu ◽  
Guanghui Su ◽  
...  
Keyword(s):  
Heat Flux ◽  
Two Phase Flow ◽  
Flow Instability ◽  
System Stability ◽  
System Control ◽  
Phase Flow ◽  
Uniform Heating ◽  
Two Phase ◽  
System Pressure ◽  
Parallel Channels

The two-phase flow instability in parallel channels heated by uniform and non-uniform heat flux has been theoretically studied in this paper. Based on the homogeneous flow model in two-phase region, the system control equations of parallel channels were established. Semi-implicit finite-difference method and staggered mesh method were used to discretize the system control equations and the difference equations were solved with a chasing method. The cosine profile and uniform constant heat flux represent the non-uniform and uniform heating condition, respectively. The marginal stability boundaries (MSB) of parallel channels and the three-dimensional instability spaces (or instability reefs) of different heat flux models were obtained. For cosine profile heating, the stability of parallel channels increases with the increase of the system pressure and inlet resistant coefficient. In high inlet subcooling region, cosine heat flux can strengthen the system stability. However, in low inlet subcooling region, the negative effect to system stability will be caused by non-uniform heating. The increase of inlet resistant coefficient will move the turning point of the MSB to high inlet subcooling number.

Numerical Simulations on Supercritical Water Flow Instability

2014 ◽  
Author(s):  
Jingjing Li ◽  
Tao Zhou ◽  
Mingqiang Song ◽  
Yanping Huang
Keyword(s):  
Numerical Simulations ◽  
Water Flow ◽  
Mass Flow ◽  
Supercritical Water ◽  
Flow Instability ◽  
Natural Circulation ◽  
Heating Power ◽  
Circulation Loop ◽  
Natural Circulation Loop ◽  
Parallel Channels

3-D simulation of supercritical water flow instability in parallel channels and a natural circulation loop are presented. Results are obtained for various heating powers. The results show that, in the natural circulation loop the steady state mass flow will firstly increase with the heating power and then decrease. And mass flow grows with the growing of the inlet temperature, decreases with the growing of system pressure. Under a large heat flux, the parallel channels will experience the flow instability of out phase mass flow oscillation. And the oscillation amplitude will grow with the growing of heating power. At last, the numerical simulations are validated by B.T. Swapnalee’s experience formula.

Theoretical Research on Flow Instability in Parallel Channels Under Motion Conditions

2013 ◽  
Author(s):  
Yingying Ma ◽  
Wenxi Tian ◽  
Guanghui Su ◽  
Libo Qian ◽  
Youjia Zhang ◽  
...  
Keyword(s):  
Flow Instability ◽  
Stability Boundary ◽  
Periodic Oscillation ◽  
Physical Models ◽  
Theoretical Research ◽  
Marginal Stability ◽  
Gravitational Acceleration ◽  
Flow Oscillation ◽  
Parallel Channels ◽  
The Mathematical Model

In motion conditions, in addition to gravitational acceleration, a new acceleration was developed and it was added to the thermal hydraulics characteristics in flow channels. The additional acceleration leads to the different thermal hydraulic characteristics and will trigger the flow oscillation and even flow instability in parallel channels. In order to study the effect of the additional acceleration on the flow oscillation, the corresponding physical models are established in this work. Through the deduction of the mathematical model, the code for flow instability under motion conditions with Gear algorithm is developed. The flow oscillation curves, critical power, marginal stability boundary (MSB) are obtained. After comparison and analysis, it is found that some motion conditions lead to flow periodic oscillation. Different flow passage position results in different oscillation amplitudes. The marginal stability boundaries (MSB) under different motion conditions fit well, that is, the effect of motion conditions on MSB is small. Number of channels has little effect; however, channel arrangement influences the flow in every channel. These conclusions are of great significance in marine reactor design.

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