[bobo5195]

for subs primary consideration is noise.

Engines of this sort can be very fuel efficant if large and expensive. The alternatives like gas turbines are normally cheaper and more eifficant.

if you want range on a sub you go nuclear but that is the kind of place where you would use stirling engines as steam turbine plant is very loud. The energy input for nuclear is enough that it can be done econmically and efficantly by using very high temps.

As cooling and for most normal uses there is no point. It will get comprehensively beaten by normal IC engines and for external combustion (low pollution) there is alot of gas turbine tech that is far far better for the heat input. As a heat pump its too large, too expensive and frankly not very good. refrigerant tech can get you better temps with focues cooling.