  We consider two modifications of a recently proposed three-terminal quantum
dot heat engine. First, we investigate the necessity of the thermalization
assumption, namely that electrons are always thermalized by inelastic processes
when traveling across the cavity where the heat is supplied. Second, we analyze
various arrangements of tunneling-coupled quantum dots in order to implement a
transmission function that is superior to the Lorentzian transmission function
of a single quantum dot. We show that the maximum power of the heat engine can
be improved by about a factor of two, even for a small number of dots, by
choosing an optimal structure.
