Stirling Engine The engine which direct heat energy to mechanical work is Stirling Engine. It is named as Stirling after the name of Robert Stirling who invented this. Any working fluid can be used in it as input. Working:- In the stirling engine there are mainly three arrangements as: Alpha-type Beta-type Gama-type Alpha type is most easiest one in which there are two cylinders connected to the crankshaft, both cylinders are connected to each other with help of pipe filled with gas/working fluid. One cylinder must be at high temperature and other be at low temperature. To maintain that high or low temperature we can use any other external substance.i.e. direct heat to one cylinder and other is at room temperature or direct cooling to one cylinder and other be at room temperature. here the above arragement is Alpha type In this when the air inside the connecting rod is being heated then it start expanding and it start pushing the piston after absorbing the certain amount of heat, then