Stability Analysis of Double-Loop Natural Circulation under Asymmetric Conditions

In order to study the stability change of double loop natural circulation under asymmetric conditions, taking the single loop natural circulation heat carrying system as the starting point, the displacement term in the dimensionless governing equation set of single loop natural circulation is expanded by Fourier expansion, and the Jacobi matrix characterizing the single loop natural circulation heat carrying system is obtained, and verification is conducted. On this basis, the Jacobi matrix analysis model of double loop is constructed. Based on the constructed model, the stability analysis of double loop natural circulation under different load difference and resistance difference is carried out, and the influence of loop geometric characteristics on the stability boundary is carried out. The results show that for a double loop system, there are two critical Reynolds numbers. When the load difference between the left and right loops is greater than these two critical Reynolds numbers, the system will become unstable. Increasing the aspect ratio, reducing the pipe diameter, increasing the length of heating section and reducing the length of cooling section can increase the range of loop stability area, and the stability boundary of reactor loop is more sensitive to the aspect ratio and the length of heating section; Besides, within the allowable range of natural circulation loop formation, increasing the loop pressure drop can improve the system stability.