چكيده به لاتين
Restrictions on the use of fossil fuels and environmental regulations have cause to extensive research into energy efficiency. Internal combustion engines are one of the largest consumers of fossil fuels in the world. 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 exhaust gases of internal combustion engine, use of Stirling engine has been suggested. For this purpose, modeling of the Stirling engine was started with using the second-order method, assuming adiabatic processes. To aproch operating conditions of the stirling engine to actual state, the real performance of the heat exchangers was added to the model. Also, heat and working losses including flow resistance when passing through the heat exchangers, engine walls heat transfer, shuttle effect, hystersis and seal leakage for each moment of the Stirling engine movement were calculated separately and added to the modeling. The sum of the mentioned cases led to the creation of Modified model. In order to validate the Modified model, modeling of "GPU-3" stirling engine was done with the mentioned method and the efficiency and production work of the engine were equal to 56/36% and 4009 watts, respectively. These values in comparison with the experimental result (efficiency of 35% and the production work of 3889 watts) show the appropriate convergence of the Modified model. The modeling of the Stirling engine was performed for three operating pressures (76/2, 13/4 and 52/5 MPa) and seven engine speed (1000 to 3500 rpm), 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 internal combustion 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 engines by using different operating conditions of stirling engine.
