Performance Study Of Radial Inflow Turbine For Organic Working Fluid

The radial inflow turbine which applied in Organic Rankine Cycle experiment system at about 120℃ is researched by both simulation and experiment in this thesis.The internal flow field of turbine for organic working fluid is analyzed by using CFD technology and the simulated results is verified by experiment, which provide a basis for performance optimization study of turbo expander. The main research results are as follows:1. The models of turbo expander for ORC experimental system are made and the internal simulation of the flow field is studied. The results show that: expect for the partial loss in the blade trailing edge and the volute tongue, the whole flow field evenly distributed in radial turbine and the isentropic efficiency of the turbine is 83.41%, which met the requirements of the original design basically.2. The performance of radial inflow turbine for organic working fluid in off-design conditions is researched. The results indicate that: the speed and pressure of turbine make a large influence on leaving loss; The inlet and outlet kinetic energy of turbine cannot be ignored in the formula of output power; There is an optimal speed range and inlet pressure that make the expander isentropic efficiency and output power reach the maximum, which the range of the optimum speed is45000~50000rpm and the optimal pressure is 0.55 MPa.3. The impact of impeller tip clearance on turbine performance is studied. Because of the influence of the gap leakage, the internal fluid flow in turbine is more complex, the expander output power and isentropic efficiency decreased by6.85% and7.97%. As the top clearance of impeller increases, the efficiency reduced and turbine flow capacity enhanced; compared with axial clearance,radial clearance make a greater impact on turbine performance.4. Experimental test on radial turbine that based on low temperature waste heat power system is studied. The results show that: the thermodynamic parameters values of turbine go well with the simulated values in stable conditions; as theinlet temperature increases, the turbine efficiency decreases and the leaving loss increases; the isentropic efficiency and output power increases as the turbine speed increases. Experimental results further validate the reliability of the results of numerical simulation.