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Abstract Natural circulation systems find extensive applications in industrial engineering systems. One of the applications is in nuclear reactor where the decay heat is removed by natural circulation of the fluid under off-normal conditions. The upcoming reactor designs make use of natural circulation in order to remove the heat from core under normal operating conditions also. These reactors employ multiple vertical fuel channels with provision of on-power refueling/defueling. Natural circulation systems are relatively simple, safe and reliable when compared to forced circulation systems. However, natural circulation systems are prone to encounter flow instabilities which are highly undesirable for various reasons. Presence of parallel channels under natural circulation makes the system more complicated. To examine the behavior of parallel channel system, studies were carried out for single-phase natural circulation flow in a multiple vertical channel system. The objective of the present work is to study the flow behavior of the parallel heated channel system under natural circulation for different operating conditions. Steady state and transient studies have been carried out in a parallel channel natural circulation system with three heated channels. The paper brings out the details of the system considered, different cases analyzed and preliminary results of studies carried out on a single-phase parallel channel system.
28Dimethyl carbonate (DMC) synthesis from methanol and carbon dioxide in the presence of ZrO2 solid solutions and yield improvement by applying a natural convection circulation system
Dimethyl carbonate (DMC) synthesis from methanol and carbon dioxide in the presence of ZrO2 solid solutions and yield improvement by applying a natural convection circulation system
Read more1Evaluation of possible leakage causes in a natural circulation helium loop
Evaluation of possible leakage causes in a natural circulation helium loop
27Experiments on the basic behavior of supercritical CO2 natural circulation
Experiments on the basic behavior of supercritical CO2 natural circulation
20A numerical and three-dimensional analysis of steady state rectangular natural circulation loop
A numerical and three-dimensional analysis of steady state rectangular natural circulation loop
Chapter 7 - Instabilities in natural circulation systems
Chapter 7 - Instabilities in natural circulation systems
12Chapter 3 - Governing differential equations for natural circulation systems
Chapter 3 - Governing differential equations for natural circulation systems
55Capability of RELAP5 code to simulate the thermal-hydraulic characteristics of open natural circulation
Capability of RELAP5 code to simulate the thermal-hydraulic characteristics of open natural circulation
Nonlinear Analysis of Onset of Nucleate Boiling in Natural Circulation under Different Pressure Conditions
In this study, we obtain the flow signals before and after the ONB through natural circulation experiments under pressure conditions of 0.15MPa and 0.3MPa. Researches were conducted by applying nonlinear analysis techniques. Results revealed that the power spectrum of volume flow data declined exponentially over time in semi logarithmic coordinates, the autocorrelation coefficient declined gradually and the phase diagram exerted the subtle structures of chaotic movement, which might prove the existence of chaos in natural circulation system. The natural convection of single phase appeared before the occurrence of ONB belonged to a non equilibrium process which showed remarkable random features. The occurrence of ONB was a process containing the beginning of chaotic motion and the continuing occurrence of bubbles at ONB and the tendency of phase change to become nucleation boiling would achieve certain states, which embodied the characteristics of chaos. In addition, the intense density difference environment of natural circulation could accelerate the occurrences of both chaotic motion and ONB. While the density difference of heated liquid decreased with the increase of pressure, which could delay the occurrence of ONB.
Read more14Numerical investigation of the effect of inlet subcooling on flow instabilities in a parallel channel natural circulation boiling system
Numerical investigation of the effect of inlet subcooling on flow instabilities in a parallel channel natural circulation boiling system
Read more6Simulation of Two-phase Natural Circulation Cooling using Air Water System
Simulation of Two-phase Natural Circulation Cooling using Air Water System
9Experimental Study of Thermal Behavior of a Single-phase Natural Circulation Loop with Vertical Heater and Cooler
The natural circulation systems have been widely applied to various technologies, for example, safety systems in molten salt reactors. Hence the instability of the natural circulation system became an exciting topic to study. This study aimed to find out the effect of horizontal width variation on the thermal behavior of a single-phase natural circulation loop (NCL) with vertical heater and vertical cooler. Three loops with horizontal widths of 50 cm, 100 cm, and 150 cm, respectively, were designed for experimental studies. Meanwhile, the vertical height of all three loops was 100 cm. The cooler was installed vertically on the upper arm of the loop to cool the fluid. The heater was installed vertically on the forearm on the other side of the loop to heat the fluid. K-type thermocouples integrated with the data acquisition system were used to measure the temperature distribution in several zones of the loop directly. The conclusion obtained in this study was a single-phase natural circulation loop with vertical heater and vertical cooler did not indicate a reversal of the direction of heat transfer at each operating power and geometry configuration. This study is expected to be one of the references to the design of a single-phase natural circulation loop as an advanced nuclear reactor passive safety system.
Read more4Experimental study on natural circulation precooling of cryogenic pump system with gas phase inlet reflux configuration
Experimental study on natural circulation precooling of cryogenic pump system with gas phase inlet reflux configuration
5A methodology to investigate the effect of vertical seismic acceleration on the qualitative dynamic behaviors of a natural circulation loop with parallel nuclear-coupled boiling channels
A methodology to investigate the effect of vertical seismic acceleration on the qualitative dynamic behaviors of a natural circulation loop with parallel nuclear-coupled boiling channels
Read more4Study of density wave instability in natural circulation with parallel channels under inclined and heaving conditions
Study of density wave instability in natural circulation with parallel channels under inclined and heaving conditions
16Experimental research on reverse flow phenomenon in an equal-height-difference natural circulation system at low pressure
Experimental research on reverse flow phenomenon in an equal-height-difference natural circulation system at low pressure
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