The convective instability in a microemulsion Phase-Change-Material slurry layer

In the present experimental study, the stability of Rayleigh-Bénard convection has been investigated in rectangular enclosures filled with microemulsion Phase-Change-Material (PCM) slurry. The PCM slurry exhibited a pseudoplastic non-Newtonian fluid behavior. Hysteresis in convection was clearly observed while the PCM were in a solid phase and in phase changing. The critical Rayleigh number decreases with the PCM mass concentration while the PCM is in phase changing. The fluid temperature at the center of the enclosure showed a time-dependent oscillation during the transition from a heat conduction state to a convection state. The maximum Nusselt number has been observed for all of the slurries while the heating plate was controlled at a temperature that most of PCM was in phase changing.