There is a relation between displacement limited rating of acoustic and electrical power (Par)with effeciency(eta):eta=Par/Per. I wanted to knw what is the relation of thermal power capacity Pe(max). (I am looking for a formula since i am making a small matlab program)?

Since i am already asking a question i was also looking for a relation between Qtco(Q when source resistance is zero) and Qtc of the closed box is there any?