Conductive Heat Transfer of Regenerator Block in Gamma Stirling Engine Model

The conductive heat transfer block is set to planar, when i try to change it to cylndrical for more realistic model as the regenerator is in fact cylindrical.

My inputs are as follows:

Inner Diameter = geometry.displacer_piston.radius

Outer Diameter = geometry.displacer_piston.radius + geometry.displacer_piston.glass_thickness

Length = regenerator.geometry.length

Conductivity (K) = regenerator.conductionHeater.k

For both of the conductive blocks, when i do that the engine simply fails to operate.

I used temperature sensors and in original model the temperature between heater and ambient are about 1550 but when i do the cylindrical modification it starts at that difference then decrease to zero as time move on

I want to understand why am i doing wrong.

[Yifeng Tang]

Is it possible to include your model for diagnostics.