| A large amount of medium and low temperature waste heat is widely existed in China. If it can be used fully, we will optimize the energy consumption structure of our country. As a new waste heat utilization technology, Organic Ranking Cycle has the advantages of high efficiency, less investment and environment friendly and can be used in the recycling of various waste heat. Therefore ORC play a vital role in the utilization of waste heat. This work presents the study of ORC system for utilizing medium and low temperature waste heat. The content of this research is as follows:Based on the basic law of thermodynamics, this work built the model of components and performance evaluation for the ORC system in MATLAB. The principle of selecting organic working fluid for this system was put forward, and the thermodynamic performances of eleven working fluids were compared in two groups. The results indicate that the thermodynamic performances of R245fa and R113 are better than of others. Besides that, the sensitivity analysis of ORC system is carried out. And it indicate that evaporating temperature, degree of superheat and condensing temperature have a large effect on the system thermodynamic performances, but degree of supercooling do not.The optimization of ORC system was carried out. Firstly, this work used genetic algorithm to investigate parameter optimization of ORC system, and obtained the maximum thermal efficiency. Secondly, a multi-objective optimization model of ORC system was built considering both of the two aspects of technology and economy, and the Pareto solutions were obtained by using NSGA-II. And the optimal solution was selected from the Pareto solutions with the aid of an ideal point. Thirdly, the ORC system with and without internal heat exchanger were compared, and the results indicate that internal heat exchanger is advantageous to improve the system thermal performance.Based on the total design scheme, the type of equipment in experimental platform was selected, and the necessary design calculation was carried out, and the parameter measurement and control system was built up. The platform mainly consists of three parts: the circuit for working fluid, heat source section and cold source section. This platform can be used for the experimental study of various working fluid. Medium and low temperature flue gas and room temperature water were regarded as heat source and cold source respectively, and the turbo expander adopted integrated design plan. |
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