Combined-type diesel engine waste heat energy recycling system

Abstract

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.

Description

technical field [0001] The present invention belongs to the energy -saving and emission reduction technology of internal combustion engines, which involves a system that recovers the heat use of multiple waste heat in diesel engines. Background technique [0002] With the increasing shortage of energy and environmental pollution, the energy conservation and emission reduction of internal combustion engines have attracted the attention of the world. At present, the energy released by the burning of diesel engine is only about 30-45 % of the energy output. Most of the other energy is discharged into the external environment in the form of waste heat, which not only caused the waste of energy and increased the burden on the cooling system in the diesel engine. The recycling of this part of energy can effectively improve the thermal efficiency of the system, reduce thermal emissions and reduce pollution. However, the residual heat generated by the engine is diverse, and the qua...

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Problems solved by technology

The organic Rankine cycle has the characteristics of high thermal efficiency for low-grade heat sources, but the single-stage Rankine cycle does not fully utilize engine cooling water, recirculated exhaust gas, and exhaust waste heat

Moreover, organic working fluids are easy to decompose at higher temperatures (generally not higher than 350 ° C), which also limits its application range

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