| The rapid development of society makes a large increase of energy resource demand. As a result, the lack of energy resource becomes more and more serious, indeed to be a bottle-neck of area development. Although our country's energy resource is abundance, but because of the large number of people and the rapid development of economic, the remained energy resource is also very austere, and it makes the energy saving to be an urgent affairs. Auto industry is one of the support industries of our country economic, and with the development of auto industry, the energy consumed by car is also increasing rapidly, therefore, the energy saving of car has been turned more and more attention. If the waste heat of the car's exhaust could be recovered and transformed to electrical power to drive the car, the consumption of fuel would be reduced, and the energy would also be saved to a certain extent. Accordingly, engine's waste heat recovery is not only an effective way to settle energy problem, but also a good way to save energy.This article mostly researched the recovery of diesel engine's exhaust heat by using a model of single screw expander Organic Rankine Cycle. The involved theories of thermodynamics are used to calculate and choose the components of this cycle.First of all, this article used GT-Power to set up BJ493ZLQ3 diesel engine model based on the mapped geometry parameters, and checked this model according to the outer characteristic curve supplied by the manufacture. This model was used to get the relation between diesel engine exhaust energy in outer characteristic curve and rotate speed, and the relation is exhaust energy is increasing with the rotate speed. According to this calculated result, plentiful of experiments had been done in a demarcated relation speed of the diesel engine, to gain the average value of exhaust temperature and average value of exhaust flux.Secondly, the principle of Organic Rankine Cycle was used to analyze and calculate the influence of different working fluid to Organic Rankine Cycle efficiency, and to non-reversible power losing, when using 28 kinds of pure working fluids. At last, four kinds of circumstance-friendly type pure working fluids R245fa,R245ca,R123,R141b were chosen to be optional working fluids of single screw expander Organic Rankine Cycle system.Thirdly, the involved theories of thermodynamics was used to analyze the influence rule of different model to efficiency, when simple Organic Rankine Cycle model,double cycle model, two stage single screw expander Organic Rankine Cycle were used separately to recover diesel engine's exhaust energy. The result of analysis is as following: the efficiency of double cycle model is the most high, but the efficiency of simple Organic Rankine Cycle model is most low, and the efficiency of two stage single screw expander Organic Rankine Cycle is in the middle.At last, the experiment platform of using simple single screw expander Organic Rankine Cycle model to recover BJ493ZLQ3 diesel engine exhaust heat was built, considering the chosen organic working fluid of R245fa. The components of this system were chosen according to the working process parameters, and it's a helpful preparation for the building of experiment platform in future.This article recovers diesel engine's exhaust heat by using single screw expander organic Rankine cycle. The content of this article was the relationship between the exhaust heat of diesel engine and the rotate rate, working fluid optimization of the organic Rankine cycle, program optimization for recovering exhaust heat of diesel engine, and the components processing of simple single screw expander organic Rankine cycle. According to the research, single screw expander organic Rankine cycle system could decrease fuel consumption ration and exhaust temperature, and provide an efficient and feasible solution.
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