Influence of aperture modification on heat storage and backup duration of solar receiver integrated with phase change material for a micro gas turbine

This study investigates the effects of receiver aperture modification, involving coupled variations in aperture diameter, frustum radius, and cone angle, on the thermal performance and backup duration of a conical cavity solar receiver integrated with eutectic Mg Si PCM and multiple heat-recovery tubes, using air as the working fluid for micro gas turbine applications. A three-dimensional numerical study is conducted for a fixed PCM mass under a solar flux of 500 kW/m 2 using ANSYS FLUENT Solar Load Model's ray tracing, with surface-to-surface radiation accounting for radiative exchange between the receiver and ambient wall. The enthalpy-porosity method is used for modeling PCM melting and solidification. Realizable k-ε turbulence model is used for the airflow inside the tubes. The results show that a reduction in the aperture diameter of the receiver improves the thermal retention and provides uniform melting across the PCM and thus higher wall temperatures. The estimated backup time provided by the PCM-integrated receiver, keeping the air outlet temperature above the turbine cutoff temperature of 1073 K, increased from 20.40 min for the baseline case to 32.66 min for a reduced aperture diameter under the same solar radiation conditions.