Thermodynamic cycle system suitable for waste heat recovery of engine for automobile

Abstract

The invention relates to a thermodynamic circulating system which is applicable to the recycling of waste heat of a vehicle engine. The thermodynamic circulating system is a coupling of low-temperature Kalina cycle used for recycling the waste heat of the cooling water of the engine and high-temperature organic Rankine cycle used for recycling the waste heat of the exhaust of the engine and the waste heat of the lubricating oil, and comprises an exhaust heat exchanger, an expansion machine, a heat exchanger, a pump, a lubricating oil heat exchanger, a lubricating oil circulating pump, a cooling water heat exchanger, a cooling water circulating pump, a heat regenerator, a throttle valve, a separator, the expansion machine, a low-pressure condenser and a pump. The system can overcome the defects that the utilization ratio of the waste heat is not high in the traditional utilization method of the waste heat of the engine, thus obviously improving the recycling efficiency of the waste heat of the vehicle engine.

Description

technical field [0001] The invention belongs to the technical field of waste heat recovery, and relates to a thermodynamic cycle system suitable for waste heat recovery of a vehicle engine. The system adopts the coupling method of Kalina Cycle and Organic Rankine Cycle to realize vehicle engine waste heat recovery and utilization. Background technique [0002] After the fuel is burned in the engine, its chemical energy is converted into heat energy, part of which is converted into useful work through the internal combustion engine cycle, which is mainly used to drive the car forward; the rest is released to the environment in the form of engine cooling waste heat and exhaust heat. According to the second law of thermodynamics, in addition to the part of waste heat energy that must be released to the environment, the rest can theoretically be used. [0003] Research shows that the heat converted into useful work by the engine accounts for about 30-40% of the calorific value ...

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Problems solved by technology

[0005] At present, the energy conversion efficiency of using the temperature difference of exhaust gas to generate electricity is very low

In the experiment, the actual thermoelectric conversion efficiency is about 2.12%, while the highest conversion efficiency of similar devices is only about 10%; the engine waste heat heating system cannot be used when the engine stops working, and the heat exchange elements are required when used in alpine regions ; The engine waste heat absorption refrigeration system has the defects of low cooling power per unit mass of refrigerant, heavy system, and low utilization rate of waste heat.

The use of engine waste heat to do work is mainly to recover the exhaust waste heat of the vehicle engine by means of thermodynamic cycle. Water is usually used as the working medium of the waste heat recovery cycle. However, the waste heat recovery efficiency of the traditional engine waste heat recovery cycle is very low. The reason is that the traditional The engine waste heat recovery cycle only recovers the exhaust waste heat of the engine, but does not recycle the waste heat of the cooling water and the lubricating oil of the engine. In addition, because the temperature of the exhaust waste heat is lower than the heat source temperature of the industrial Rankine cycle, the use of water As a circulating working fluid, the efficiency of waste heat recovery is very low

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