Research On The Single Screw Expander And Organic Rankine Cycle System

The waste heat and pressure recovery is one of the key technologies in improving energy efficiency. Currently there are a lot of small-scale waste heat resources in our industry, which have not been fully utilized due to lacking of effective technical means, resulting in a low overall energy efficiency. Therefore, the development of a new and efficient low temperature waste heat power generation system has great significance in improving energy efficiency.Based on the characteristics of low temperature waste heat, a power generation system combined by a single screw expander and Organic Rankine Cycle was put forward to improve the low efficient use of waste heat. Firstly, the author designed and built a basic performance test bench of single screw expanders with compressed air as the power source. The characteristic curves in full load and different valve opening and the performance curve in different humidity and backing pressure were obtained. The experimental results of the single screw expander prototype indicated that: during the operation, single screw expander runs steadily with low noise, it has good power output characteristics, the maximum output power may reach 5kW,and the temperature drops significantly, up to 63℃; But the efficiency of the prototype is not very satisfactory, there are still many imperfections especially the large mechanical loss. However the maximum mechanical efficiency may reach 95%, the isentropic efficiency 59% and the overall efficiency 35%. The prototype basically meets the preliminary design, meanwhile there is also considerable room for improvement.Secondly, the method of determining the main parameters about the organic Rankine cycle system with 400℃flue gas as power source was proposed, and the main parameters of the system which two kinds of refrigerant R134a and R245fa were used in calculated by matlab. With 400℃flue gas as power source, the advantages and disadvantages of two refrigerants were compared and the influence of superheat degree on the circulatory system of the organic Rankine was also analyzed. The calculations of the Organic Rankine Cycle system with the flue gas as the power resource show that, for the refrigerant R134a and R245fa, overheating does not have much significant on increasing the output power of the thermodynamic system. And the performance of R134a is better than R245fa on the basis of comprehensive comparisons in lower temperature. However, R245fa is better in higher temperature.Finally, a experimental system of Organic Rankine Cycle power generation with single screw expander was designed and built on the basis of the performance test of the expander. In addition, in this paper, the application case of the Organic Rankine Cycle power generation system with single screw expander which was used in the low temperature waste heat power recovery was designed and analyzed innovatively in the future.