Flow boiling instability of liquid nitrogen in horizontal mini channels

In the study, flow boiling instability in horizontal mini-channels is investigated by developing a numerical model that couples flow boiling with the flow supply of liquid nitrogen. The model is validated relative to the experimental results. The results indicate that the heat flux and inlet subcooling significantly influence steady-state characteristic curves. Transient responses of Ledinegg instability, density wave, and pressure drop oscillations are investigated, and comparisons with room-temperature fluids are presented. With respect to the Ledinegg instability, the flow is stabilized away from the site where a positive flow disturbance occurs at the two-phase negative slope region, and the flow exhibits periodic oscillations initially when the negative disturbance is applied. With respect to the conditions of the density wave and pressure drop oscillations, the flow exhibits periodic oscillations when disturbance occurs. The characteristics of the three types of instability of liquid nitrogen flow boiling are compared with those of water/refrigerant fluids.