Ultra-compact post-processing system, supercharger assembly and engine

A supercharger assembly, comprising a supercharger body and an ultra-compact post-processing system, wherein

• the ultra-compact post-processing system comprises:
• a mixer, which is provided with an inlet joint to be connected with a supercharger body;
• a urea nozzle connected to the inlet joint;
• a shell provided outside a part of the mixer and provided with a gas outlet;
• and
• a catalytic disc, wherein
• the catalytic disc is positioned inside the shell, arranged between an outer periphery of the mixer and an inner wall of the shell, and divides an inner cavity of the shell into a mixing cavity and a gas-return cavity,
• the gas outlet of the shell is located at the gas-return cavity, and an outlet end of the mixer is provided with a mixing section that is located in the mixing cavity, and
• the supercharger body is provided with a supercharger outlet, which is connected to the inlet joint of the ultra-compact post-processing system.