Two-dimensional model of the air flow and temperature distribution in a cavity-type heat receiver of a solar stirling engine

A theoretical study on the air flow and temperature in the hear receiver, a ffected by free convection, of a Stirling Engine for a Dish/Stirling Engine Power System is presented. The standard k-epsilon turbulence model for the fluid flow has been used and the boundary conditions employed were obtaine d using a second level mathematical model of the Stirling Engine working cy cle. Physical models for the distribution of the solar insolation from the Concentrator on the bottom and side walls of the cavity-type heat receiver have been taken into account. The numerical results show that most of the h eat losses in the receiver are due to re-radiation from the cavity and cond uction through the walls of the cavity. It is in the region of the boundary of the input window of the heat receiver where there is a sensible reducti on in the temperature in the shell of the heat exchangers and this is due t o the free convection of the air. Further, the numerical results show that convective heat losses increase with decreasing tilt angle.