The invention discloses a multi-grade
waste heat energy
cascade recycling
system for a
diesel engine, and particularly relates to a combined-type
diesel engine waste heat energy recycling system. The
waste heat energy recycling system is structurally characterized in that a high-temperature
Rankine cycle system is composed of a working medium pump, a
thermoelectric generator, an EGR
heat exchanger, an
exhaust heat exchanger, a
steam turbine, a condenser and the like of a high-temperature system; a low-temperature
Rankine cycle system is composed of a working medium pump, an EGR
heat exchanger, an
exhaust heat exchanger, the cylinder
body cooling water
heat exchanger, the supercharged air heat exchanger, a
steam turbine, a condenser and the like of a low-temperature system. A middle electrical
machine is arranged between a
turbine motor and a
supercharger; the waste heat of cooling water, supercharged air, exhausted gas, EGR recirculated
waste gas and the like are utilized, and through the high-temperature and low-temperature organic Rankine cycles, thermoelectric power generation,
turbine direct power generation and the like, heat exchange can be carried out between various kinds of waste heat generated by the
diesel engine and working media sequentially according to the grade. Due to arrangement of the middle electrical
machine, the
expansion ratio of the exhausted gas can be improved, and excess pressure energy of the exhausted gas can be directly recycled. Full recycling of multi-grade waste
heat energy of an
internal combustion engine can be achieved, irreversible losses of the system are reduced, the fuel economical efficiency is effectively improved, and therefore the aims of saving energy and reducing emissions are achieved.