Triangular cycle and Rankine cycle combined waste heat recovery system and method thereof

Abstract

The invention discloses a triangular cycle and Rankine cycle combined waste heat recovery system and a method thereof. The waste heat recovery system comprises working medium pumps, evaporators, expansion machines and condensers. In a triangular cycle, a working medium enters the high-temperature cycle evaporator, absorbs heat, always maintains a liquid state, and then, enters the expansion machine to act, and waste steam after acting preheats a low-temperature working medium in a Rankine cycle in the high-temperature cycle condenser; and in the Rankine cycle, the working medium enters the high-temperature cycle condenser, is in heat exchange with waste steam in the triangular cycle, then, enters the low-temperature cycle evaporator, is in counterflow heat exchange with low-temperature tail gas which is already in heat exchange with the high-temperature working medium in the high-temperature cycle, and then, enters the low-temperature cycle expansion machine to act. According to the triangular cycle and Rankine cycle combined waste heat recovery system, the working medium isothermal heat absorption process in the traditional Rankine cycle in the high-temperature cycle evaporator can be eliminated in the triangular cycle, the temperature matching problem between a heat source and the working mediums is solved, energy loss of the system is reduced, and efficient recycling of waste heat of automobile tail gas is facilitated.

Description

technical field [0001] The invention relates to the application field of waste heat recovery from automobile engine exhaust, in particular to a waste heat recovery system based on the combination of a triangular cycle and a Rankine cycle and a method thereof. Background technique [0002] The energy generated by the fuel during the combustion process of the engine is not completely converted into the kinetic energy of the car. Except for the consumption of the electrical system and the friction of the mechanical system, about 30%-40% of the energy is discharged into the atmosphere in the form of exhaust heat. Considering the huge number of internal combustion engine vehicles, if the waste heat from vehicle exhaust can be recovered and used, it will effectively improve the fuel economy of vehicles and greatly reduce greenhouse gas emissions. [0003] However, the waste heat of automobile exhaust belongs to low-grade waste heat, and the organic Rankine cycle is an effective te...

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Problems solved by technology

[0006] The problem to be solved by the present invention is to propose a waste heat recovery system and method combining a triangular cycle and a Rankine cycle for the low energy utilization rate of the traditional organic Rankine cycle in the process of realizing low-grade waste heat utilization

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