Study on Factors Affecting CHF Based on Factorial Analysis in Narrow Rectangular Channel Under Natural Circulation

2018 ◽  
Author(s):  
Li Zichao ◽  
Zhou Tao ◽  
Shi Shun ◽  
Amir Haider ◽  
Li Bing ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Influencing Factors ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Factorial Analysis ◽  
Contribution Rate ◽  
Factors Affecting ◽  
System Pressure

Research on influencing factors of CHF in narrow rectangular channel under natural circulation is of great significance to the safety of reactors. Taking the narrow rectangular experimental device as the research object, influencing factors of CHF in narrow rectangular channel were experimentally studied under natural circulation. With factorial analysis, effects of different factors and their interactions on CHF were analyzed. It is found that the contribution rate of mass flow rate is the largest, followed by the effect of outlet dryness, followed by the effect of system pressure. Their interactions between different factors have little effects on CHF in narrow rectangular channel under natural circulation.

Research on Powder Stream of Coaxial Powder Feeding in Laser Manufacturing Technology

2013 ◽  
Vol 423-426 ◽  
pp. 807-810
Author(s):  
Heng Quan ◽  
Yun Shan Wang ◽  
Li Feng Liu ◽  
Shao Jun Liu ◽  
Qing Ruo Meng
Keyword(s):  
Physical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Concentration Field ◽  
Ccd Camera ◽  
Factors Affecting ◽  
Coaxial Nozzle ◽  
Powder Mass ◽  
Powder Feeding

Mathematical-physical model of powder stream in coaxial powder feeding was established. The concentration fields of powder stream of coaxial nozzle of different size and powder mass flow rate were analyzed. The concentration field and morphology of the powder stream were detected by CCD camera. The results show that the size of coaxial nozzle and powder mass flow rate are major factors affecting the powder stream. The mathematical-physical model and experimental data provide theoretical basis for laser cladding manufacturing.

Data Analysis of 64 Rod Bundles Reflood Heat Transfer Experiment

2017 ◽  
Author(s):  
Lv Yufeng ◽  
Chen Yuzhou ◽  
Zhang Dongxu ◽  
Zhao Minfu ◽  
Duan Minghui
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Test Data ◽  
Mass Flow ◽  
Flow Rate ◽  
High Mass ◽  
Rod Bundles ◽  
Transfer Experiment ◽  
System Pressure ◽  
Injection Water

The test data of 64 rod bundles reflood heat transfer experiment performed by China Institute of Atomic Energy are analyzed. The heater rods are electrically powered and have a diameter of 9.5 mm and a length of 4.3 m arranged in a 8 × 8 array with a 12.6 mm pitch. The test parameter is in the range of 10–500 kg/(m2 · s) for injection water mass flux, 20–80°C for injection water temperature, 500–600°C for initial heater rod temperature, 0–1.1 kW/m for heating power, respectively. The system pressure is atmosphere pressure. Two kinds of spacer grids with and without mixing vanes are adopted to investigate their effect on heat transfer. The result shows that rod wall temperature downstream the spacer grid with mixing vanes is lower than that without mixing vanes, which indicates that the heat transfer is enhanced with mixing vanes. The rewetting velocity is nearly a constant under a certain test condition. The experimental values of rewetting velocity are compared with heat conduction controlled theories. At low mass flow rate, one-dimensional conduction gives agreement with experiment; while at high mass flow rate, the two-dimensional conduction theory is shown to be in agreement with experiment data. The RELAP5/ MOD3.3 reflood model is assessed against the test data. Comparison of code prediction and measured data indicates that the code predicts quench time relatively well but the peak rod temperature differs.

Flow Characteristics on Fluidized Powder Conveying in a Horizontal Rectangular Channel

2015 ◽  
Author(s):  
Koichiro Ogata ◽  
Sumito Yamashita ◽  
Tomoya Hirose
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Glass Beads ◽  
Horizontal Channel ◽  
Solid Loading ◽  
Loading Ratio ◽  
Minimum Fluidizing Velocity

This study experimentally examined the dense phase pneumatic conveying in a horizontal rectangular channel using the fluidizing air. The powder used is PVC belong to Geldart A particle, where the mean diameter is 151μm, the particle density is 1382kg/m3 and the minimum fluidizing velocity is 9.0mm/s. As the experimental conditions, the fluidizing velocity at the bottom of a vessel and the horizontal channel has been changed. Also, the mass of transported powder, the supply air pressure and the height of powder bed inside a vessel were measured. In the case of PVC, we confirmed the flow characteristics of the powder conveying and air pressure. Further, we found that the fluidizing air to the bottom of a vessel was required to the powder conveying of this system, and that the fluidizing velocity at the horizontal channel needs to be larger than the minimum fluidizing velocity. These results were also obtained on the previous study when two kinds of glass bead was used. The mass flow rate and solid loading ratio were estimated by the measured data of the mass of transported powder. In addition, these results were compared with the conveying characteristic of two kinds of glass beads belongs to Geldart A and B particle. As a result, the mass flow rate and solid loading ratio of PVC were smaller than that of two kinds of glass beads.

Experimental Research on Pulsating Two-Phase Flow Pressure Drop Characteristics in Horizontal Rectangular Channel

2014 ◽  
Author(s):  
Siqi Zhang ◽  
Puzhen Gao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Phase Flow ◽  
Two Phase ◽  
Mean Values ◽  
Water Mass Flow Rate

In spite of most previous studies since 1970, the theory of pulsating pipe flows supported by experimental investigations has not yet completed in comparison with the well-defined theory of steady pipe flows. Therefore, it seems that there is much to be done about experimental research in this field. In order to determine the resistance characteristics of two-phase flow under pulsatile conditions, an experimental investigation on two-phase flow with periodically fluctuating flow rates in a narrow rectangular channel is carried out. A frequency inverter is used to obtain experimental conditions with different fluctuating frequencies, amplitudes and mean values of water mass flow rate. After obtaining experimental results, comparisons between experimental frictional pressure drop values and theoretical calculations have been done. Two-phase flow on pulsating conditions is far more complicated than that on steady conditions because pulsating flow is composed of two parts: a steady component and a superimposed periodical time varying component called oscillation. In this paper, the influence of different fluctuating frequencies, amplitudes and mean values of liquid and gas mass flow rate on two-phase flow pressure drop characteristics is also discussed. The results show that the total pressure drop and water mass flow rate change with the same fluctuating period except for a phase difference. The phase lag also changes with the fluctuating frequencies and amplitude. The accelerating pressure drop changes dramatically in a fluctuating period, especially at the end of acceleration. Also, the time when the acceleration pressure drop has its maximum value lags the time when the acceleration reaches its peak, mainly because of the inertial of the fluid.

Heat Transfer in a Two-Inlet Rotating Pin-Fin Roughened Rectangular Channel With Side-Wall Fluid Extraction

2018 ◽  
Author(s):  
Yanan Chen ◽  
Jie Wen ◽  
Guoqiang Xu ◽  
Zhiliang Du ◽  
Yunqing Dai
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rectangular Channel ◽  
Side Wall ◽  
Flow Rate Ratio ◽  
Cooling Channel ◽  
Inlet Channel ◽  
Pin Fin

The heat transfer characteristics in a rotating pin-fin roughened rectangular channel with an aspect ratio of 4:1 is investigated, simulating a rotor blade trailing edge. The copper plate regional average method is used to determine the heat transfer coefficient. A second inlet is added at the inner top corner of the traditional one-inlet cooling channel to improve heat transfer in the high radius region. Coolant from these two inlets mixes in the middle of the channel, and then exits through eight sidewall slots. The channel is assembled in a rotating facility, and the symmetrical plane of the rectangular channel is orientated at an angle of 135° with respect to the rotation plane. The mass flow rate of the bottom inlet is kept at a constant (Re1 = 20,000), whereas the inlet mass flow rate ratio (MR, second inlet mass flow rate/bottom inlet mass flow rate) changes from 0 to around 0.55. Results show that the second inlet improves the heat transfer in the proximity of the second inlet extensively, but the overall averaged heat transfer is decreased a bit compared to the one inlet channel. Moreover, with the local MR, the heat transfer data at different locations converge into the same trend, indicating that the local MR should be a good parameter in describing the flow in this pin-fin cooling channel. In the rotating one-inlet channel (MR = 0), a critical Ro phenomenon is observed. After the critical point, rotation stops decreasing heat transfer and starts to elevate it. A lower critical Ro is observed at higher radius location but the corresponding local Ro is a constant at around 1.0. In rotating two-inlet channel, the overall heat transfer enhancement caused by rotation is almost in the same level with different MR, indicating that high MR cases (MR > 0.2) is not recommended because the coolant from the second inlet is not efficiently used.

scholarly journals Detailed Evaluation of the Natural Circulation Mass Flow Rate of Water Propelled by Using an Air Injection

2008 ◽  
Vol 45 (3) ◽  
pp. 238-243 ◽  
Author(s):  
Rae-Joon PARK ◽  
Kwang-Soon HA ◽  
Jae-Cheol KIM ◽  
Seong-Wan HONG ◽  
Sang-Baik KIM
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Air Injection ◽  
Detailed Evaluation

Research on Natural Circulation Flow Characteristics of Floating Nuclear Power Plant in Heaving Motion

2017 ◽  
Author(s):  
Li Ren ◽  
Peng Minjun ◽  
Xia Genglei ◽  
Zhao Yanan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Natural Circulation ◽  
Flow Characteristics ◽  
Circulation Flow ◽  
Drift Flux Model

The FNPP (Floating Nuclear Power Plant) expanded the application field of Integrated Pressurized Water Reactor (IPWR) in the movable marine platform, it is necessary to study the natural circulation flow characteristics in heaving motion on the ocean. From the characteristics of FNPP, by means of THEATRe code which was based on the two-phase drift flux model and was modified by adding module calculating the effect of heaving motion, the simulation model in heaving motion was built. Using the models developed, the natural circulation operating characteristics of natural circulation in heaving motion and the transitions between forced circulation and natural circulation are analyzed. In the case of amplitude limited, the periods of mass flow rate are equal to periods of heaving motion. The oscillation amplitude of mass flow rate increases with the heaving amplitude increase. In the case of period limited, the natural circulation flow rate oscillating amplitude increases with the heaving period increases. The result obtained are not only evaluating FNPP design behavior properly but also pointing out the direction to further optimum design to ensure FNPP operating safety in heaving motion.

scholarly journals Assessment of Modified RELAP5 MOD3.2 Against LBE Natural Circulation Test Loops

2021 ◽  
Vol 9 ◽  
Author(s):  
Yufeng Lv ◽  
Xingmin Liu ◽  
Weihan Li ◽  
Chunqiu Guo ◽  
Zhiwei Zhou
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Hydraulic Analysis ◽  
Original Performance ◽  
Nuclear Systems ◽  
Simulation Results ◽  
Thermal Hydraulic Analysis ◽  
Thermo Physical Properties

Motivated by the significant natural circulation capability of lead–bismuth eutectic (LBE)–cooled systems, the RELAP5 MOD3.2 code was modified for the analysis of LBE-cooled reactors and non-nuclear systems. The thermo-physical properties of LBE have been incorporated into the code without affecting the code’s original performance; new heat transfer correlations for liquid metal have been implemented. For the purpose of validating the modified code, experimental results of two different LBE natural circulation test loops were compared with the code simulation results. The first one was a natural circulation setup process test at a power of 22.5 kW performed at the Natural Circulation Experimental (NACIE) facility. The simulated inlet and outlet LBE temperatures across the heat source and mass flow rate of LBE agreed well with the test data. The second one was natural circulation conditions under five different power levels conducted at the Natural Circulation Capability Loop (NCCL) facility. The LBE temperature difference and mass flow rate under different power levels predicted by the code were consistent with the experimental data. Generally speaking, the modified code gives acceptable results, and the code could be applied for further LBE systems thermal-hydraulic analysis.

Two-phase natural circulation loop behaviour at atmospheric and subatmospheric conditions

2018 ◽  
Vol 233 (4) ◽  
pp. 687-700
Author(s):  
S Venkata Sai Sudheer ◽  
K Kiran Kumar ◽  
Karthik Balasubramanian
Keyword(s):  
Heat Flux ◽  
Physical Properties ◽  
Spatial Variation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Two Phase ◽  
Natural Circulation Loop ◽  
Thermo Physical Properties

This paper aims to present the steady-state behaviour of two-phase natural circulation loop at atmospheric and sub-atmospheric conditions. One-dimensional numerical approach is adopted to evaluate various system parameters, with special emphasis on spatial variation of thermo-physical properties and flashing. Homogeneous equilibrium model is applied for two-phase flows. An in-house code is developed in MATLAB to solve numerical model iteratively. It is observed that consideration of spatial variation of thermo-physical properties can precisely predict the loop behaviour. The evaluated results are validated with the open literature and reasonably good agreement is observed. The heater inlet temperature, inlet pressure and heat flux are found to have significant influence on spatial variation of pressure, temperature and enthalpy. As system pressure decreases from atmospheric to sub-atmospheric (1–0.8 atm), it is observed that the sub-atmospheric loop gives a higher mass flow rate compared to atmospheric loop at lower heat fluxes. However, as the heat flux increases in the sub-atmospheric loop, the mass flow rate is reduced due to increased drag force in the loop.

Steady-State Energetic and Exergetic Performances of Single-Phase Natural Circulation Loop With Hybrid Nanofluids

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Mayaram Sahu ◽  
Jahar Sarkar
Keyword(s):  
Steady State ◽  
Mass Flow Rate ◽  
Entropy Generation ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Hybrid Nanofluid ◽  
Natural Circulation Loop ◽  
Hybrid Nanofluids

Energy and exergy performances of natural circulation loop (NCL) with various water-based hybrid nanofluids (Al2O3 + TiO2, Al2O3 + CNT, Al2O3 + Ag, Al2O3 + Cu, Al2O3 + CuO, Al2O3 + graphene) with 1% volumetric concentration are compared in this study. New thermophysical property models have been proposed for hybrid nanofluids with different particle shapes and mixture ratio. Effects of power input, loop diameter, loop height, loop inclination and heater/cooler inclination on steady-state mass flow rate, effectiveness, and entropy generation are discussed as well. Results show that both the steady-state mass flow rate and energy–exergy performance are enhanced by using the hybrid nanofluids, except Al2O3 + graphene, which shows the performance decrement within the studied power range. Al2O3 + Ag hybrid nanofluid shows highest enhancement in mass flow rate of 4.8% compared to water. The shape of nanoparticle has shown a significant effect on steady-state performance; hybrid nanofluid having cylindrical and platelet shape nanoparticles yields lower mass flow rate than that of spherical shape. Mass flow rate increases with the increasing loop diameter and height, whereas decreases with the increasing loop and heater/cooler inclinations. Both effectiveness and entropy generation increase with the decreasing loop diameter and height, whereas increasing the loop and heater/cooler inclinations. This study reveals that the particle shape has a significant effect on the performance of hybrid nanofluids in NCL, and the use of hybrid nanofluid is more effective for higher power.

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