Performance Analysis And Optimization Research Of Mid-low- Temperature Waste Heat Power Generation Using Organic Rankine Cycle

There is large amount of mid-low-temperature waste heat in China, especially in the industrial field. If it can be used fully, we will save tremendous energy for the whole country. Power generation system based on Organic Rankine Cycle(ORC) has the advantages: simple system, high efficiency, environment friendly, strong adaptability to load, and so on. Therefore, it'll play a vital role in the utilization of mid-low-temperature waste heat. This work presents the study of the system, detail of this work is as follows:Firstly, this work built the model of main components and performance evaluation, and the global model for the ORC system. The logic diagram for calculating the global model was drawn and a software called EES was used for programming. Learning from principle of selecting working fluid for the power generation system using ORC at home and abroad, principle of selecting working fluid for the system was put forward, based on which, 16 potential working fluids suit for the system were picked out from 49 working fluids. applicable condition, isentropic and saturated properties of the working fluids was studied. For the 16 working fluids, system performance under subcritical or supercritical condition was analyzed and optimized, and the optimal performance was compared by programming. Through the comparation, R152a was determined as the optimal working fluid.Then, taking R152a as the working fluid, this work optimized the system, whose operating condition is in supercritical region. This work added internal heat exchanger(IHX) to the basic system, and compared the performance of system without and with IHX by programming. Some discovery was summarized as below: after adding the IHX, the thermal performance of the system goes up, the cost of investment goes up slightly, in the long run, the profit outweighs the disadvantage. In view of the improved system, by the way of multi-objective optimization, the condition for designing and system performance which meets the actual need of engineering was obtained.Based on it, this work analysed the exergy loss of every component. The result shows that the exergy loss of the expander is about 40% of the total exergy loss. Through the comparision of various types, inward-flow-radial turbine was selected. Internal efficiency was determined as the evaluating indicator. Optimization of the expander was carried out by programming. After the optimization, the internal efficiency is up to 80.13%. Meanwhile, the basic thermal and structural parameters was got. Based on the program, this work developed the software which is used for the thermal design and characteristic analysis of the inward-flow-radial turbine.The research results will be theoretical basic for the exploitation of mid-low-temperature waste heat power generation technology and provide some theoretical guidance for the next step experiment.So, it has important theoretical value and realistic significance for promoting the energy saving and emission reduction in our country.