Study On Natural Circulation Flow In a Closed Loop : 2nd Report, Stability Analysis of Flow in a Loop with an Inverse U-Shaped Cooler

Abstract

An analysis of the stability of natural circulation in a closed loop with an inverse U-shaped cooler was performed. The loop consists of an inverse U-shaped tube cooler heating boxes and connecting bent pipes. The calculate flow at a steady state was obtained by one-dimensional analysis using a simplified loop model of the test loop. Stability of the natural circulation flow was studied by linear stability : the flow was investigated by linearized equations to determine whether perturbation of the temperature and the flow rate added in the steady state flow would grow or diappear. Nyquist criterion was used to predict the stability limit. The curves for neutral stability were obtained as a function of the two parameters, non-dimensional cooler heat flux and non-dimensional flow rate, for the various elvation differences between the cooler and the heater. The effect of experimental parameters on the flow stability was studied. The comparison between analysis and experiment showed favorable agreement.