Organic Rankine cycle diesel engine tail gas and waste heat utilization system using two-stage single-screw expanding machine

Abstract

The invention relates to an organic Rankine cycle diesel engine tail gas and waste heat utilization system using a two-stage single-screw expanding machine, belonging to the field of energy conservation and emission reduction, and mainly comprising a gas compressor, an engine, a turbomachine, a tube bundle type evaporator, a single-screw expanding machine I, a magnetic powder dynamometer I, a single-screw expanding machine II, a magnetic powder dynamometer II, a plate type condenser, a liquid storage tank, a working medium pump, an intermediate heater, a cooling tower, an adjustable flow pump, a flow divider valve I of an expanding machine outlet, a flow divider valve II of the expanding machine outlet, a flow divider valve III of the expanding machine outlet, an exhaust control valve I, an exhaust control valve II, a turbomachine and compressor coupling shaft, a coupling shaft I, a coupling shaft II and various connecting pipelines. According to the conditions of different rotating speeds and different loads of a diesel engine, by utilizing the invention, the opening and closing of the flow divider valves of the expanding machine outlet and the exhaust control valves are adjusted, waste heat recoveries at different levels are realized and the energy taken away by the tail gas of the diesel engine is furthest recovered and utilized.

Description

technical field [0001] The invention relates to a two-stage single-screw expander organic Rankine cycle diesel engine tail gas waste heat utilization system, which is mainly used for recycling the heat taken away by the tail gas of a vehicle diesel engine, and belongs to the field of energy saving and emission reduction. Background technique [0002] According to heat balance analysis, the heat converted into effective work in a diesel engine only accounts for 30%-45% of the heat emitted by fuel combustion, while 25%-45% of the total heat of fuel combustion is discharged with the exhaust gas. If some technical means are used to recover the heat taken away by the exhaust gas of the diesel engine, it can not only improve the comprehensive energy utilization rate of the diesel engine, but also have a significant fuel-saving effect. [0003] At present, the methods of recovering the energy taken away by the exhaust gas of diesel engines mainly include exhaust gas turbocharging t...

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Problems solved by technology

The working fluid used in the classic Rankine cycle is water. Under normal pressure, steam will only appear when the temperature reaches 100°C. The design of the turbine requires that no liquid droplets appear in the turbine, so the evaporation temperature of the system is at 100°C. ℃ and above, the system can be guaranteed to be in a normal operating state; in addition, the latent heat of vaporization of water is very large compared with organic working fluids, and the heat that water needs to absorb when changing from a saturated liquid state to a saturated gas state is relatively higher than that of organic working fluids. The mass is very large, so the requirements for the heat source are relatively high, and the energy of the low-grade heat source cannot be absorbed; while the output power of the turbomachinery that can be seen on the market is tens of kilowatts or more, and the turbine is used as an expansion machine. In the Ken cycle, what is needed is a heat source with a large flow and high temperature, but it is difficult to recover a heat source with a small flow and low temperature

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