Stirling's air engine - a thermodynamic appreciation

Stirling's original engine is remarkable for having been the first applicat ion of the thermal regenerator-and an instant technological success. While the patents and their intriguing history are the normal focus of study, thi s paper shifts attention to the insights afforded by reconstructing the the rmodynamic personality of the engine itself. The kinematics of the drive me chanism are recovered, and volume variations determined as a function of cr ank angle. Recently developed thermodynamic tools are introduced and applie d to the construction of the fluid particle trajectory map. The map forms t he integration grid for calculation of the temperature response of the rege nerator. The claim for 2 bhp from the original engine is explored. Potentia l is identified for an up-to-date version of Stirling's elegant concept in the form of cheap quiet power units of attractive specific output.