Endoreversible thermodynamics was discovered multiple times, with Reitlinger (1929), Novikov (1957) and Chambadal (1957), although it is most often attributed to Curzon & Ahlborn (1975). 
Reitlinger derived it by considering a heat exchanger receiving heat from a finite hot stream fed by a combustion process.
A brief review of the history of rediscoveries is in.