Ansys Employee

You need to figure out what's in the model. If the block is present in both cases, you can use a source into the solid volume. Or you add a flux through a surface, a profile may be suitable for that. 

Shell conduction means heat can conduct along a thin wall, otherwise it can't. The heat generation doesn't need shell conduction and is a way to get heat into a thin wall: typical use case could be underfloor heating or heating jackets on pipes.