Investigations on the Role of Secondary Convection Currents in Single-Phase Natural Circulation Loop Dynamics
Naveen Kumar1,a, J. B. Doshi2 and P. K. Vijayan1,b
1Reactor Engineering Division, Bhabha Atomic Research Centre Trombay, Mumbai 400 085, India.
aknaveen@barc.gov.in
bvijayanp@barc.gov.in
2Department of Mechanical Engineering, IIT Bombay, Mumbai 400 076, India.
doshi@me.iitb.ac.in
ABSTRACT
Fluid axial diffusion plays an important role in singlephase natural circulation system dynamics. Present 1-D models are unable to account for fluid axial diffusion. Start-up from rest cannot be simulated because of the inherent tendency of the predicted dynamics to be attracted by zero flow condition. In this paper, a model has been developed to account for fluid axial diffusion. The model is based on an order of magnitude analysis. The model developed has been incorporated in a 1-D model developed by the authors previously. The application of model to a rectangular singlephase natural circulation loop show that the model can predict the loop behaviour from start-up with a reasonable accuracy. The results of the analysis carried out have been presented. The model successfully predicts the unidirectional, bidirectional and chaotic behaviour observed in such loops.
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