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Modern diesel engines are struggling to enhance the power density. This is usually realized by being equipped with a turbocharger, which demands higher performances on exhaust flow and exhaust waste energy recovery (WER). In the present study, we investigated the variations of exhaust flow and exhaust energy recovery performance with different geometrical parameters of exhaust system and proposed an evaluation and optimal design method of the exhaust system for a turbocharging diesel engine with a module pulse converter (MPC) system. The macro engine performances and the micro flow fields in exhaust system are obtained from the one/three dimensional (1D-3D) coupling simulation, and the energy of exhaust gas is quantified and analyzed with a concept of air power. It can be concluded that with a view to the exhaust performance and exhaust energy utilization, the diameter of the exhaust pipe should be set equal to the outlet diameter of the manifold and there is an optimized value of the contraction rate of the exhaust manifold. Besides, a parameter of the exhaust system called power potential coefficient is proposed to qualitatively evaluate the exhaust performance and exhaust energy. [ABSTRACT FROM AUTHOR]