Research And Numerical Calculation On The Performance Of Radial-inflow Turbine For Organic Rankine Cycle

The Organic Rankine Cycle(ORC)has obvious advantages in the utilization of low-temperature heat source.In the cycle,an expander is the key component to convert low-grade thermal energy into useful energy,and its performance plays an important role in the system.Under same low temperature heat source parameters(150?),six kinds of dry working fluids were chosen to confirm design condition of radial-inward-flow turbine of organic working fluids,the sieve method was used for parameter optimization and thermodynamic design of turbine design,and analyzing the matching of the thermodynamic design scheme of different working fluid turbines with heat source.The calculation results show that the designed relative internal efficiency of turbine using R600 a is mediacy,but the system has maximum thermal efficiency of 9.17% and the largest internal power of 80.70 kW,respectively.The system has thermal efficiency of 8.44% for using R123 and the lowest internal power of 68.53 kW.The thermal efficiency and internal power of radial-inflow turbines system using the R245fa?R600 and R600 a respectively as working fluids are higher has better matching attribute with the given heat source condition,but combined with the need of safety,R245 fa should be a better working fluid.On the basis of the design parameters,three-dimensional modeling and numerical simulation were carried out,analyzing flow fields of flow path and overall performance of the turbines combined system thermal performance parameters.According to the analysis and comparison of the CFD simulation results,compared with the radial-inflow turbine using R245 fa as working fluid,the flow field distribution of through flow part for R600 turbine is reasonable relatively.The result shows that the radial-inflow turbine using R600 as working fluid has the advantages of high relative internal efficiency?high system output and good thermal matching with specific low grade heat source,respectively reaching 74.28% and 73.98 kW.Numerical simulations are used in the design and off-design conditions for the turbine,including sliding-parameters and sliding-pressure with variation of heat source parameters.To obtain the precise parameters about performance of the turbine,a novel method of reconfiguration process is proposed.Based on the method,the performance of the turbine in the off-design conditions can be predicted and analyzed.The results show that there is an optimal relative internal efficiency of the turbine during the off-design conditions and the decrease of the power output compared with the design condition.Exhausted velocity loss is the largest among all the losses in the turbine.The drop of the heat source temperature leads to the efficiency decline.Compared with the turbine relative internal efficiency,the ideal cycle thermal efficiency has a greater impact on the system thermal efficiency.Combined with the performances of the turbine and the system,in the off-design conditions with variation of heat source parameters,the performance of sliding-pressure has more advantages than the one of sliding-parameters,and has better matching with off-design conditions.