Validation of SAS4A/SASSYS-1 for predicting steady-state single-phase natural circulation

2021 ◽  
Vol 377 ◽  
pp. 111149
Author(s):  
Taiyang Zhang ◽  
Erik R. Smith ◽  
Caleb S. Brooks ◽  
Thomas H. Fanning
Keyword(s):  
Steady State ◽  
Single Phase ◽  
Natural Circulation

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.

Experimental and Numerical Investigation of a Single-Phase Square Natural Circulation Loop

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Ritabrata Saha ◽  
Swarnendu Sen ◽  
Saikat Mookherjee ◽  
Koushik Ghosh ◽  
Achintya Mukhopadhyay ◽  
...  
Keyword(s):  
Steady State ◽  
Ambient Temperature ◽  
Single Phase ◽  
Numerical Models ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Periodic Oscillations ◽  
Heater Power ◽  
Natural Circulation Loop ◽  
Moderate Power

Experimental and numerical analyses are carried out for a natural circulation loop (NCL) under low and moderate heater power. The effect of ambient temperature variation on the loop thermal behavior has been taken into account in present study. The effect of liquid inertia has a role in the initial transience, as revealed by the numerical and experimental observations. The steady-state results from the present analyses are validated with the reported dimensionless results for NCL. The experimental steady-state results are in fair agreement with the developed lumped numerical models. At moderate power, the numerical and experimental results indicate periodic oscillations.

scholarly journals Effect of Loop Diameter on the Steady State and Stability Behaviour of Single-Phase and Two-Phase Natural Circulation Loops

2008 ◽  
Vol 2008 ◽  
pp. 1-17 ◽  
Author(s):  
P. K. Vijayan ◽  
A. K. Nayak ◽  
D. Saha ◽  
M. R. Gartia
Keyword(s):  
Steady State ◽  
Driving Force ◽  
Power Plants ◽  
Single Phase ◽  
Natural Circulation ◽  
Two Phase ◽  
Stability Behavior ◽  
The Stability ◽  
Riser Height ◽  
Heat Transport Capability

In natural circulation loops, the driving force is usually low as it depends on the riser height which is generally of the order of a few meters. The heat transport capability of natural circulation loops (NCLs) is directly proportional to the flow rate it can generate. With low driving force, the straightforward way to enhance the flow is to reduce the frictional losses. A simple way to do this is to increase the loop diameter which can be easily adopted in pressure tube designs such as the AHWR and the natural circulation boilers employed in fossil-fuelled power plants. Further, the loop diameter also plays an important role on the stability behavior. An extensive experimental and theoretical investigation of the effect of loop diameter on the steady state and stability behavior of single- and two-phase natural circulation loops have been carried out and the results of this study are presented in this paper.

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