Design And Key Technologies Research On Multi-Operating Condition Reaction Velocity Type Carbon Dioxide Expander

The development of human society is inseparable from the support of various energy sources.At present,non-renewable energy is still the main energy supply of human society.In order to improve the utilization efficiency of non-renewable energy,a series of thermodynamic cycle systems have been developed.However,the traditional thermodynamic cycle system has low energy utilization rate and the emission of synthetic circulating refrigerant into the air will pollute the environment.Therefore,CO₂is used to replace the synthetic circulating refrigerant in the system,and a series of studies on the CO₂thermodynamic cycle system are carried out.In order to improve the cycle efficiency of the CO₂thermodynamic cycle system,the structural innovation design and research of the expander in the CO₂thermodynamic cycle system is conducted in this thesis.On the basis of summarizing and analyzing the research status at home and abroad,a kind of new structural form of multi-condition reaction-type speed expander is proposed here.In order to enable the expander to adapt to the working conditions of the working medium under variable working conditions,a new valve group structure is introduced into the expander,and the valve and the expansion flow channel are designed respectively.With the controlling of the valve,the working medium of the expansion flow channel inlet under variable working conditions could be controlled within a small pressure range,thereby the system energy loss caused by the changing of system working conditions could be reduced.The main work is as follows:（1）Firstly,the structure,working principle and application of various types of valves are studied and analyzed.Then,combined with the operation mechanism of the expander and the purpose of the design of the expander valve,an automatic valve group that could meet the working conditions of the variable working conditions is designed.With the control of the automatic valve group,the working refrigerant from the expander inlet under variable working conditions could be shunted,so that the pressure of the working refrigerant at the inlet of the expansion channel is controlled within a small pressure range,thereby the energy loss of the working refrigerant in the expansion channel could be reduced.（2）The expansion process of the working refrigerant in the flow channel is studied and analyzed,and the variation law of the cross-sectional area of the expansion channel with the expansion of the working refrigerant is obtained,so that,the calculation method of the structural parameters of the expansion channel is teased out.Combined with the pre-designed opening and closing pressure range of the valve unit in the automatic valve group,the mid-pressure of the pressure range of the working refrigerant adapted to the valve unit is used as the design pressure of the expansion channel,and the calculation of the structural parameters of the expansion channel is completed.（3）The automatic valve group and the expansion channels are arranged in the expansion turbine reasonably,and then the structural design of the expansion turbine structure is completed.Then the expansion turbine is reasonably connected with the power generation part,and finally the overall structure of the expander is designed and the 3D model of the expander is completed.Finally,the processing scheme of the expansion turbine is analyzed and designed,and the processing and manufacturing of the expansion turbine are completed.The structure of a new type of expander designed in this thesis provides a choice for how to reduce the degree of excessive expansion or inadequate expansion of the working refrigerant in the forward thermodynamic cycle system of thermal power generation under variable operating conditions and how to recycle the expansion work in the process of working refrigerant expansion and pressure reduction in the reverse thermodynamic cycle system of refrigeration and heat pump.