Natural circulation of saturated fluid in a differentially heated toroidal loop is considered. Since the density of the saturated fluid can change significantly even by small variations of the enthalpy, the usual Boussinesq approximation cannot be applied.
Effects of loop inclination $\theta_0$, vapor to liquid state ratio $x_0$, and heating rate A on the flow characteristics are investigated. Although the homogeneous one-dimensional analysis gives two possible steady state solutions, the linearized stability analysis shows only one solution can be stable. In this linearly unstable region, the flow shows periodic, period doubling, and chaotic behaviors as in single-phase analysis. Finally, non-Boussinesq approximated results are compared with the single-phase analysis by Boussinesq approximation.
