Experimental Study of Temperature and Heating Power Variations on Natural Circulation Flow Phenomena in a Closed Rectangular Loop With Single Heating Channel

2020 ◽  
Author(s):  
Solomon Bello ◽  
Puzhen Gao ◽  
Yuqi Lin
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Nuclear Reactor ◽  
Natural Circulation ◽  
Reactor Power ◽  
Heating Power ◽  
Inlet Temperature ◽  
Heating Channel ◽  
Flow Loop ◽  
Pressure Drops

Abstract Experimental investigation has been carried out in a closed loop rectangular natural circulation facility having a single heated macro channel dimensioned and built based on concepts of similarity and scale down circuit similar to the primary loop of a Nuclear reactor. The study aims to observe and critically analyze the thermal hydraulic parameters (Temperature Variation, Heating Power rises) as it affects transfer of heat by the NC flow along its hydraulic circuit at predetermined inlet subcooled set and sustained at 40°C, 50°C, 60°C and 80°C by regulating the coolant flow rate in the secondary loop. Heating channel power varies between 7kW – 13kW to portray several conditions of the reactor power in response to temperature changes base on the inlet temperature as a way of sustaining single-Phase flow through the flow loop while suppressing instabilities in the fluid circulation. Real-time signals of thermal hydraulic responses are observed via a graphical interface for data acquisition when stable flow or self-sustained flow oscillations are achieved. Results were analyzed at the (1) inlet and outlet of heater, (2) along the heated section and (3) inlet and outlet of condenser (4) the entire Loop. Pressure drops and Flow rate with respect to Temperature Difference was also analyzed to contribute for the acquisition of important data of natural circulation phenomena to be used for the design of large scale (prototypical) NC facility.

Temperature Transients in a Triple Heat Exchanger

1984 ◽  
Vol 198 (3) ◽  
pp. 145-154
Author(s):  
P C Chiu ◽  
E H K Fung
Keyword(s):  
Heat Exchanger ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Solar Heating ◽  
Inlet Temperature ◽  
Exchange Processes ◽  
Flow Experiments ◽  
Heating Plant ◽  
Reactor Power Plant ◽  
Secondary Fluid

A triple heat exchanger, so called because there are three heat exchange processes taking place in it, was built to simulate the system behaviour of a nuclear reactor power plant or a solar heating plant which is characterized by the two circulating loops of the fluid flow. Experiments were carried out to study the temperature transients under disturbances in secondary fluid inlet temperature and power output from immersion heaters. Numerical results were obtained from the weighted residual formulation of the proposed dynamic model and they were shown to be in general agreement with the two sets of experimental responses.

A High Effective Parallel Method for the Coupling Between Neutronics and Thermal-Hydraulic

2016 ◽  
Author(s):  
Xiaomeng Dong ◽  
Zhijian Zhang ◽  
Zhaofei Tian ◽  
Lei Li ◽  
Guangliang Chen
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Large Scale ◽  
Nuclear Reactor ◽  
Reactor Core ◽  
Decisive Role ◽  
Reactor Power ◽  
Coupling Method ◽  
Outlet Temperature

Multi-physics coupling analysis is one of the most important fields among the analysis of nuclear power plant. The basis of multi-physics coupling is the coupling between neutronics and thermal-hydraulic because it plays a decisive role in the computation of reactor power, outlet temperature of the reactor core and pressure of vessel, which determines the economy and security of the nuclear power plant. This paper develops a coupling method which uses OPENFOAM and the REMARK code. OPENFOAM is a 3-dimension CFD open-source code for thermal-hydraulic, and the REMARK code (produced by GSE Systems) is a real-time simulation multi-group core model for neutronics while it solves diffusion equations. Additionally, a coupled computation using these two codes is new and has not been done. The method is tested and verified using data of the QINSHAN Phase II typical nuclear reactor which will have 16 × 121 elements. The coupled code has been modified to adapt unlimited CPUs after parallelization. With the further development and additional testing, this coupling method has the potential to extend to a more large-scale and accurate computation.

A Comparative Study of Single-Phase, Two-Phase, and Supercritical Natural Circulation in a Rectangular Loop

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
P. K. Vijayan ◽  
M. Sharma ◽  
D. S. Pilkhwal ◽  
D. Saha ◽  
R. K. Sinha
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Significant Influence ◽  
Single Phase ◽  
Natural Circulation ◽  
Phase Region ◽  
Inlet Temperature ◽  
Two Phase ◽  
Supercritical Region ◽  
Stability Performance

A one-dimensional theoretical model has been used to analyze the steady state and stability performance of a single-phase, two-phase, and supercritical natural circulation in a uniform diameter rectangular loop. Parametric influences of diameter, inlet temperature, and system pressure on the steady state and stability performance have been studied. In the single-phase liquid filled region, the flow rate is found to increase monotonically with power. On the other hand, the flow rate in two-phase natural circulation systems is found to initially increase, reach a peak, and then decrease with power. For the supercritical region also, the steady state behavior is found to be similar to that of the two-phase region. However, if the heater inlet temperature is beyond the pseudo critical value, then the performance is similar to single-phase loops. Also, the supercritical natural circulation flow rate decreases drastically during this condition. With an increase in loop diameter, the flow rate is found to enhance for all the three regions of operation. Pressure has a significant influence on the flow rate in the two-phase region, marginal effect in the supercritical region, and practically no effect in the single-phase region. With the increase in loop diameter, operation in the single-phase and supercritical regions is found to destabilize, whereas the two-phase loops are found to stabilize. Again, pressure has a significant influence on stability in the two-phase region.

A Comparative Study of Single-Phase, Two-Phase and Supercritical Natural Circulation in a Rectangular Loop

2009 ◽  
Author(s):  
P. K. Vijayan ◽  
D. S. Pilkhwal ◽  
M. Sharma ◽  
D. Saha ◽  
R. K. Sinha
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Significant Influence ◽  
Single Phase ◽  
Natural Circulation ◽  
Phase Region ◽  
Inlet Temperature ◽  
Two Phase ◽  
Supercritical Region ◽  
Stability Performance

A one dimensional theoretical model has been used to analyze the steady state and stability performance of single-phase, two-phase and supercritical natural circulation in a uniform diameter rectangular loop. Parametric influences of diameter, inlet temperature and system pressure on the steady state and stability performance has been studied. In the single-phase liquid filled region, the flow rate is found to increase monotonically with power. On the other hand the flow rate in two-phase NCS is found to initially increase, reach a peak and then decrease with power. For the supercritical region also, the steady state behaviour is found to be similar to that of two-phase region. However, if the heater inlet temperature is beyond the pseudo critical value, then the performance is similar to single-phase loops. Also, the supercritical natural circulation flow rate decreases drastically during this condition. With increase in loop diameter, the flow rate is found to enhance for all the three regions of operation. Pressure has a significant influence on flow rate in two-phase region marginal effect in supercritical region and practically no effect in the single-phase region. With increase in loop diameter, operation in the single-phase and supercritical regions is found to destabilize whereas the two-phase loops are found to stabilize. Again, pressure has a significant influence on stability in the two-phase region.

scholarly journals SPARK-NC: A Lead-Bismuth-Cooled Small Modular Fast Reactor with Natural Circulation and Load Following Capabilities

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5410
Author(s):  
Muhammad Hashim ◽  
Liangzhi Cao ◽  
Shengcheng Zhou ◽  
Rubing Ma ◽  
Yiqiong Shao ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Power Distribution ◽  
Natural Circulation ◽  
Conservation Equation ◽  
Reactor Power ◽  
Inlet Temperature ◽  
Primary Control ◽  
The Core ◽  
Load Following ◽  
Energy Conservation Equation

In this study, a conceptual design was developed for a lead-bismuth-cooled small modular fast reactor SPARK-NC with natural circulation and load following capabilities. The nominal rated power was set to 10 MWe, and the power can be manipulated from 5 MWe to 10 MWe during the whole core lifetime. The core of the SPARK-NC can be operated for eight effective full power years (EFPYs) without refueling. The core neutronics and thermal-hydraulics design calculations were performed using the SARAX code and the natural circulation capability of the SPARK-NC was investigated by employing the energy conservation equation, pressure drop equation and quasi-static reactivity balance equation. In order to flatten the radial power distribution, three radial zones were constructed by employing different fuel enrichments and fuel pin diameters. To provide an adequate shutdown margin, two independent systems, i.e., a control system and a scram system, were introduced in the core. The control assemblies were further classified into two types: primary control assemblies used for reactivity control and power flattening and secondary control assemblies (with relatively smaller reactivity worth) used for power regulation. The load following capability of SPARK-NC was assessed using the quasi-static reactivity balance method. By comparing three possible approaches for adjusting the reactor power output, it was shown that the method of adjusting the coolant inlet temperature was viable, practically easy to implement and favored for the load following operation.

Study on the Influence Factors of Heat Transfer Coefficient of Supercritical Water Under Different Circulation Modes

2020 ◽  
Author(s):  
Peng Xu ◽  
Tao Zhou ◽  
Jialei Zhang ◽  
Juan Chen ◽  
Zhongguan Fu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flow ◽  
Flow Rate ◽  
Supercritical Water ◽  
Natural Circulation ◽  
Inlet Temperature ◽  
The Heat Transfer Coefficient

Abstract There are many factors that can affect the heat transfer coefficient (HTC) of supercritical water in forced and natural circulation. The correlation between the factors with the HTC under different circulation modes has an important influence on the reactor core design. By extracting the experimental data of supercritical water in forced circulation and natural circulation, the grey correlation model was used to analyze the relational degree between these factors with HTC. The results show that: Under the condition of forced circulation, there is a positive correlation between the inlet temperature, mass flow velocity, the thickness of the grid body with the HTC of supercritical water, and the order is: mass flow velocity > inlet temperature > the thickness of the grid body; there is a negative correlation between the pressure, heat flux with the heat transfer coefficient of supercritical water, and the order is: pressure > heat flux. Under the condition of natural circulation, there is a positively correlation between heating power, inlet temperature and circulation flow rate with HTC, and the order of magnitude is: circulation flow rate > heating power > inlet temperature; diameter and pressure are negatively correlated with heat transfer coefficient, and the order of magnitude is: pressure > diameter. In the two circulation modes, mass flow rate is an important factor affecting the heat transfer capacity of supercritical water, while the effect of heat flux on the heat transfer coefficient is contrary.

An Assessment of the Thermodynamic Performance of Mixed Gas-Steam Cycles: Part B — Water-Injected and Hat Cycles

1994 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza ◽  
Ennio Macchi ◽  
Stefano Consonni
Keyword(s):  
Mass Transfer ◽  
Gas Turbine ◽  
Heat Mass Transfer ◽  
Large Scale ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Specific Work ◽  
Mixed Gas ◽  
Pressure Drops ◽  
Water Mixing

Part B of this paper focuses on intercooled recuperated cycles where water is injected to improve both efficiency and power output. This concept is investigated for two basic cycle configurations: a Recuperated Water Injected (RWI) cycle, where water is simply injected downstream the HP compressor, and a Humid Air Turbine (HAT) cycle, where air/water mixing is accomplished in a counter-current heat/mass transfer column called “saturator”. For both configurations we discuss the selection and the optimization of the main cycle parameters, and track the variations of efficiency and specific work with overall gas turbine pressure ratio and turbine inlet temperature (TIT). TIT can vary to take advantage of lower gas turbine coolant temperatures, but only within the capabilities of current technology. For HAT cycles we also address the modelization of the saturator and the sensitivity to the most crucial characteristics of novel components (temperature differences and pressure drops in heat/mass transfer equipment). The efficiency penalties associated to each process are evaluated by a second-law analysis which also includes the cycles considered in Part A. For any given TIT in the range considered (1250 to 1500°C), the more reversible air/water mixing mechanism realized in the saturator allows HAT cycles to achieve efficiencies about 2 percentage points higher than those of RWI cycles: at the TIT of 1500°C made possible by intercooling, state-of-the-art aero-engines embodying the above cycle modifications can reach net electrical efficiencies of about 57% and 55%, respectively. This compares to efficiencies slightly below 56% achievable by combined cycles based upon large-scale heavy duty machines with TIT = 1280°C.

Studies on Source Effect in Experimental Design for Passive Cooling in Large Cavities Under LOCA conditions

2013 ◽  
Author(s):  
Shengqiang Li ◽  
Yin Xiong ◽  
Yalei Hao ◽  
Hongyu Zhu ◽  
Shengyao Jiang
Keyword(s):  
Experimental Design ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Large Scale ◽  
Natural Circulation ◽  
System Level ◽  
Design Parameters ◽  
Passive Cooling ◽  
Pressurize Water Reactor

In recent years, most of the advanced Pressurize Water Reactor (PWR) design contains passive cooling features, especially for the containments, which are functioning as the final radioactive emission barriers. To evaluate the best estimation codes for containment design, large scale thermo-hydraulic experimental facilities will be necessary for Code Verification and validation (V&V). Normally, the multi-phase jet is the main source for containment thermo-hydraulic processes under Loss of Coolant Accident (LOCA) conditions. This paper presents the scaling studies of source effects in large cavity experiment facility design. The similarity in core safety features, such as cavity temperature and pressure, is preserved firstly in the scaling and some dominant design parameters are given. Some primary design features are decided. The jet mass flow rate and heat sink surface ratios are provided for the prevailing parameters for system transient simulation. Based on mass and energy conservative equations, the parameters ratio for jet mass flow rate, jet time scale, jet integral energy, break size and expansion structures size are determined. Furthermore, some transient multidimensional phenomena are also considered. A novel six regions hierarchical model is similarly provided specially for cavity space scaling. The interaction between jet and space natural circulation was modeled. The local heat and mass transfer simulation and system level evaluation are coherence in the experimental design. Based on the preceding results, estimation for distortion on experiments can also be made to evaluate the experimental data deviations from prototype design.

Validation of RELAP5/MOD3.4 for Flashing-Induced Instabilities in a Natural Circulation Loop

2020 ◽  
Author(s):  
Yifan Xu ◽  
Minjun Peng ◽  
Genglei Xia ◽  
Yanan Zhao
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Flow Instability ◽  
Natural Circulation ◽  
Density Wave ◽  
System Stability ◽  
Test Facility ◽  
Circulation System ◽  
Inlet Temperature ◽  
Relap5 Code

Abstract This paper aims to validate the effectiveness of the widely used Relap5 code in simulating two-phase natural circulation, and its capability to predict flashing-induced instabilities. The RELAP5 code is validated against experimental data from the NMR test facility, which was designed to investigate the flow instability for a BWR-type novel modular reactor (NMR). The simulations by RELAP5/MOD3.4 code had been performed under various conditions by changing system pressure, core inlet subcooling, core inlet flow resistance, and core heat power etc. The flow stability for a certain operating condition could be determined from the time trace profile of the loop natural circulation flow rate. The results showed that the simulated mass flow rate increased with increasing core inlet temperature, reproducing the experimental trend. And the maximum error between the experimental data and the calculated results is within 10%. The predicted natural circulation dimensionless numbers, the phase change number and inlet subcooling number, also had a good agreement with the experimental data. In general, the RELAP5 code is able to simulate flashing-induced instability and density wave oscillations, which occurred in the natural circulation test facility at low pressures. However, flashing tends to be suppressed at a higher pressure (400kPa). And the enlargement of core inlet resistance coefficient can also have a positive impact on natural circulation system stability.

Experimental Observation of the General Trends of the Steady State and Instability Behavior of Supercritical Water Natural Circulation

2013 ◽  
Author(s):  
Fa Lv ◽  
Yan-ping Huang ◽  
Yan-lin Wang ◽  
Xiao Yan
Keyword(s):  
Steady State ◽  
Water Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Supercritical Water ◽  
Natural Circulation ◽  
Water Pressure ◽  
Heating Power ◽  
Heated Zone

Experimental study on steady state and instability behavior of subcritical and supercritical water natural circulation was performed in a rectangular loop (NPIC-SCNCL) in NPIC, with the pressure of 10 and 21.1∼24.8MPa. According to the experimental results, in steady state the natural circulation displayed higher mass flow rate, heating power and outlet water temperature of the heated zone under supercritical pressure (22.2∼24.8Mpa) than those under subcritical pressure (10MPa). The effects of heating power and water pressure on the steady state behavior of supercritical water natural circulation were also carried out. In the experiments, natural circulation showed instability both in supercritical and subcritical conditions. The results showed that the natural circulation instability appeared when the outlet water temperature of the heated zone got close to the critical temperature under supercritcial pressure. In comparion, the natural circulation instability appeared when the outlet water temperature of the heated zone got close to the saturated temperature in subcritical condition. The instability behavior of supercritical water natural circulation showed the fluctuations of the mass flow rate, water temperature and pressure et al. In the experiments, we also observed that the fluctuations of the parameters mentioned above for supercritical water natural circulation instability could disappear when the heating power is big enough which seemed that the natural circulation returned to a new steady state.

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