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S. Entezari,I. Chitsaz,S. Kazemzadeh Hanani,M. Monemi 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2
Most of the vehicle pollutants during emission tests are raised from catalyst inefficiency during cold start. Catalysts usually convert harmful emissions only when their temperature reaches around 250 °C to 350 °C. In this research, the vortex tube is implemented to recover the waste heat energy of exhaust gas during the cold start to improve catalyst heating. The experiments are conducted on the turbocharged direct-injection gasoline engine to extract the boundary conditions of numerical simulations. Numerical simulations are performed to evaluate the effects of different hot exhaust mass fractions on the flow regime and waste heat recovery. The results reveal that the level of turbulence inside the vortex tube increases for higher hot mass fractions that lead to lower exhaust temperature on the hot side. By implementing the vortex tube, the maximum temperature at the hot exhaust is related to 20 % of the hot mass fraction and after that, the hot exhaust temperature decreases. By implementing the vortex tube, gas temperature before the catalyst is reached to 658 K at 52.3 % hot mass fraction which shows 48 K increase in exhaust temperature before the catalyst. At this point, 300 W heat is transferred to the exhaust gas that improves transient cold start time.