Investigation on the role of mass flow rate in UTSG reverse flow under natural circulation condition

2019 ◽  
Vol 132 ◽  
pp. 763-772 ◽  
Author(s):  
Zhigang Xu ◽  
Huaran Ji ◽  
Gang Hong ◽  
Boshen Bian ◽  
Yanping Huang ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Reverse Flow ◽  
Natural Circulation ◽  
Circulation Condition

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.

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.

scholarly journals Development of circuit model with natural circulation of coolant under conditions of ship motion

Vestnik IGEU ◽  
2021 ◽  
pp. 19-26
Author(s):  
A.M. Samoilov ◽  
A.A. Sataev ◽  
A.A. Blokhin ◽  
V.V. Ivanov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Natural Circulation ◽  
Ship Motion ◽  
Nuclear Power Installation ◽  
Testing Bench

Safety is the key requirement to any nuclear power installation. Various factors affect safety during operation of the nuclear power installation. These factors are difficult to study due to the high economic costs. This problem can be solved by developing prototype models to conduct the research of many complex processes. Dynamic impact on the ship installation is one of these processes. The most significant impact is the impact on the natural circulation of the coolant, that is one of the basic emergency safety systems. Also, it is a promising way to ensure movement in the main circulation circuit. The purpose of this paper is to assess the influence of external dynamic forces on the processes of natural circulation. For the study a testing bench has been developed that simulates one of the circulation loops of the reactor unit. The basic method to obtain experimental data is temperature sounding of the specific sections of the circulation route. A mathematical model has been developed that describes this process. The model is based on the equations of momentum conservation and heat balance. In accordance with the experimental data, the calculation of natural circulation for static and dynamic modes has been carried out. A mathematical model to describe this process has been developed. A comparative analysis of the results of calculating the static and dynamic modes has been carried out. It is founded out that the decrease of mass flow rate is about 10 % as compared with the static regime. It confirms the qualitative effect of ship motion on natural circulation. The practical significance of the research is the development of a model under conditions of ship motion, as well as verification of the model at the testing bench. The results show a significant effect of ship motion on the mass flow rate of the coolant in the case of natural circulation. Thus, to ensure the required safety of ship installations, it is recommended to conduct a study of natural circulation in accordance with the developed model under conditions of maximum possible ship motion.

Experimental Investigation in Turbocharger Compressors During Surge Operation

2020 ◽  
Author(s):  
Silvia Marelli ◽  
Anna Misley ◽  
Marco Ferrando
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Internal Combustion Engines ◽  
Reverse Flow ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Boost Pressure ◽  
Pass System

Abstract Flow instabilities in centrifugal compressors are one of the most limiting factors to the performance of the system where the compressor is installed (i.e., internal combustion engines, fuel cell, etc.). A better understanding of the surge phenomenon allows to properly set-up the operative region of the turbomachine in order to avoid a decrease in performance and to prevent the risk of damage. Actually, the instability phenomenon of surge can seriously damage the compressor for vibrations and temperature stress. To avoid damage to the compressor, the maximum boost pressure is generally limited with a by-pass system, reducing the mass flow rate provided by the machine. The results of a broad experimental investigation performed at the turbocharger test bench of the University of Genoa are reported to deeply analyze the behavior of a small centrifugal compressor. A specific circuit adaptable in volume and length is used to study the effect of different configurations on steady compressor performance with special reference to the unstable operation. Measurements of instantaneous pressure and mass flow rate signals are performed in different sections located upstream and downstream the turbomachine. The difficulties related to measurement of instantaneous fluid-dynamics parameters in the turbocharging circuit and data post-processing are highlighted under unsteady flow conditions occurring in surge operation. The effect of the compressor operating conditions (i.e., turbocharger rotational speed) and the circuit geometry is studied during the transition from steady to unsteady operation. In particular, the hysteresis loops surrounding the steady state map are reported highlighting filling and emptying and wave action phenomena, also in the region of zero mass flow and in the case of reverse flow condition. All measured quantities presented in this paper are the time synchronous averages of a large number of consecutive cycles in deep surge operation. The aim of the paper is to extensively analyze the compressor behavior in unstable operating conditions in order to improve simulation models such as a physics-based compressor model previously developed by the Authors.

Sign in / Sign up

Export Citation Format

Share Document