Hello,
You do not need an additional UDS to solve the solid temperature in the porous zone. In the case of the non-thermal equilibrium model, Fluent will simply create an additional solid cell zone (which is spatially coincident with its fluid zone) and solves the energy equation in both these cell zones for their respective temperature. You do not need to add another scalar equation for this.
Hope this answers your question.
Thanks.
Best,
Karthik