Utilization of Stirling engine to improve the performance and fuel consumption of an internal combustion engine by exhaust gas heat recovery

About 30 to 40 percent of the total energy produced in internal combustion engines is converted into useful mechanical work at best, and the rest is transferred to the environment through exhaust gases and engine cooling systems. One effective way to overcome mentioned issue is to recover the exhaust gas heat of internal combustion engines. In the present study, in order to recover the wasted energy from the ICE exhaust gases, use of Stirling engine has been suggested. For this purpose, modeling of the Stirling engine was performed by using the second-order method. To approach operating conditions of the stirling engine to actual state, heat and working losses for each moment of the engine movement were calculated separately and added to the modeling. The modeling of the Stirling engine was performed for three operating pressures in different engine speeds, depending on the thermal energy of the internal combustion engine. The results show that, at best condition, Stirling engine produce 5/8 to 10 horsepower and 20 to 22 N.m of torque. By adding these values to the IC engine, we will see a significant increase in power and torque of the hybrid system. It is also possible to achieve a constant torque over a wide range of engine speeds in hybrid engine by using different operating conditions of stirling engine.