Performance analysis of bladeless jet propulsion micro-steam turbine for micro-CHP (combined heat and power) systems utilizing low-grade heat sources

Recently, the micro CHP (combined heat and power) systems were developed to utilize the various low-grade heat sources in the industrial and residential sectors. However, the low-grade heat sources for micro-CHP systems were unsuitable for application to the conventional blade-type micro-steam turbines, because the low-grade heat sources of the saturated steam conditions included with condensing droplets caused blade erosion. The bladeless jet propulsion micro-steam turbine, a new-concept turbine, has been designed to operate with the low-grade heat sources of saturated steam conditions. In this paper, the theoretical study predicted the performance of this turbine under the given condition, while the experimental study was performed to obtain the performance factors. We estimated the amounts of turbine loss and the reasons for the losses through a comparison of the theoretical and experimental results. In the experimental results, we obtained an electrical power of 1.5 kW and a turbine efficiency of 6.3% at the pressure ratio of 4. These results show the application potential to micro-CHP system using low-grade heat sources. We also concluded that the bladeless jet propulsion micro-steam turbine can be applied to micro-CHP systems in the industrial and residential sectors if the performance of the turbine can be increased through improvements.