Influence of intake pressure on the performance of single screw expander working with compressed air

In order to meet the demand of small expander in the field of waste heat recovery, distributed renewable energy, gas liquefaction and compressed air vehicles, a single screw expander with 175 mm diameter rotor is developed in our lab. An experimental system using compressed air has been built to test the performance of single screw expanders. The experiments were conducted for different intake pressure, and important parameters were measured, such as flow rate, intake and exhaust temperature, output power and rotating speed. The influence of intake pressure on the performance was obtained. Results indicate that satisfactory power output and economic performance can be obtained at high intake pressure and high rotational speed, meanwhile a good working efficiency is maintained. The speed of 2800 rpm is considered as the best working speed, and fitting formulae are given for dynamic performances versus intake pressures. The highest overall efficiency that can be reached is 55% and the maximum output reached is 22 kW. The preliminary experimental study indicates a very good working performance for the first generation of self-developed single screw expanders.