Numerical study on the effect of dissymmetry heating on flow instability of supercritical water in two parallel channels

The effect of dissymmetry heating on flow instability of supercritical water in two parallel vertical upward channels is investigated by a time-domain model. It is found that dissymmetry heating imposes different effects on the system stability under different inlet mass flow or inlet fluid temperature. This is because that mass flow distribution presents different response characteristics to heat load distribution, and critical mass velocity (G_cr) determines this characteristics. When average mass velocity in the channel (G) is below G_cr under low inlet mass flow, the system presents positive response characteristics and system stability increases with dissymmetry heating degree. With the increase of inlet mass flow, positive response characteristics turn to negative response characteristics when G is higher than G_cr. When the system presents negative response characteristics, system stability decreases with dissymmetry heating degree. The stronger the system response characteristics, the more obvious the effect of dissymmetry heating on system stability.