Investigation on Static Characteristics of Self-lubricated Aerostatic Thrust Bearing of Organic Rankine Cycle Turbine Driven by Nuclear Heat

The nuclear power system of micro reactor with organic Rankine cycle is an effective approach to achieve multiple energy supply in special scenarios. The utilization of organic working fluid lubricated air bearing in organic Rankine cycle turbine generator set can eliminate the complex lubrication oil system, which is an effective measure to improve the compactness of the system. In order to investigate the static characteristics of organic working fluid lubricated air bearing, this paper focuses on the organic working fluid aerostatic thrust bearing, and the influence of inlet pressure, inlet temperature, and rotation speed on loading capacity and mass flow rate is discussed in detail. In addition, the effects of orifice type, axial clearance, and lubricating working fluid are further analyzed. The results show that under different operating conditions, the film pressure distribution characteristics remain basically consistent. The pressure gradually decreases radially from the orifice area to the outlet. Under the conditions with high inlet pressure, high inlet temperature and low rotation speed, the loading capacity can be kept at a high level. Compared to the thrust bearing with small orifice, bearings with slots have higher loading capacity and lower mass flow rate under the same inlet area. As the axial clearance increases, the film pressure significantly decreases, the loading capacity decreases, and the mass flow rate increases. The lubricating working fluid has a certain influence on the static characteristics. In most conditions, bearing lubricated by R134a performs the best static characteristics, followed by cyclopentane bearing, and R245fa bearing presents the relatively worst performance. The results in this paper can provide vital reference for the design optimization of organic working fluid lubricating bearings.