Investigation of the performance and flow characteristics of two-phase reaction turbines in total flow geothermal systems

Abstract

In a total flow geothermal system, the two-phase turbine can generate output power and recover fresh water for the water-deficient area. The performance of the two-phase turbine under various working conditions is significantly affected by operation parameters of the geothermal system. This paper presented performance evaluation methods of two-phase turbines, including one-dimensional (1D) method, two-dimensional (2D) method and three-dimensional (3D) method. The 1D method was a fast iteration approach and could reflect average flow parameters along the impeller channel. The 2D method included nonuniform effects in the rotational direction and the 3D method could derive the complete 3D flow in the channel using CFD methods. The three models were validated with experimental results under various rotational speeds. Compared with the 3D method, the 1D method and the 2D method could significantly reduce computational time. The performance of the two-phase reaction turbine was evaluated under various working conditions. A correction method based on 1D and 3D results was proposed to generate the performance map and evaluate the influence of operation parameters of the geothermal system on the turbine performance. Proposed methods and analysis can be widely used in the design, selection and operation of two-phase reaction turbines for various thermal systems.