Simulation And Performance Analysis Of Flow Characteristics In Blade Disc Turbine

With the shortage of traditional fossil fuels and the aggravation of environmental pollution,clean and renewable energy and the recycling of waste heat resources has gradually become a key research point in the current energy research field.Organic Rankine cycle(ORC)is an effective way to utilize low-grade thermal energy,and how to select suitable turbine for ORC system has become a key research direction in recent years.As an unconventional turbine form,disc turbine has the advantages of low cost and can be easily small-scaled,which is especially suitable for small-scale ORC systems.Meanwhile,disc turbines have not been commercially used due to the low efficiency and low operation torque.In this paper,a new type of disc turbine structure is designed by adding blades based on the traditional disc turbine structure,and a three-dimensional mathematical model is established for the improved disc turbine with blades.The established mathematical model can calculate the fluid velocity and pressure distribution in the narrow channel between adjacent discs,as well as the operation torque,output power and efficiency of the turbine.CFD software 'Fluent17.0' was used to conduct numerical simulation calculation on the internal flow of a single narrow channel between two adjacent discs,and the numerical simulation results were used to verify the validity of the mathematical model established in this paper.Using the mathematical model established in this paper,the performance analyses were made between the disc turbine with blades and traditional bladeless disc turbine.The calculation results showed that the operation torque of disc turbine with air as working medium nearly doubled after increasing the blades,while the turbine efficiency increased from 20% to 55.31%.At the end of the paper,a simulation analysis model of ORC power generation system with a blade disc turbine as the prime motor was established to study the influence of different working media and operating parameters on the performance of ORC power generation system.The results showed that the thermal efficiency of the system is proportional to the critical temperature of the organic working medium.When using R123 as the working medium,the thermal efficiency of the ORC system reached 16.98%.The research of this paper shows that the blade disc turbine is one of the power equipment suitable for small-scale ORC power generation system with low temperature heat source because of its compact structure,low cost and relative high efficiency.