Optimization design and analysis of a novel total flow and Kalina cycle coupled system driven on low-medium temperature geothermal source with two-phase mixture

•A novel total flow and Kalina cycle coupled system on geothermal energy is designed.•Thermodynamic and mathematical models of proposed system are established.•Optimized design condition parameters of the novel system are obtained by using PSO.•Effects of evaporating pressure and basic concentration on performance are analyzed.•Trends of exergy destructions in components are calculated and display. A novel total flow and Kalina cycle coupled system has been proposed to utilize the geothermal energy with a certain dryness. To confirm the feasibility and advantages of the proposed system, Particle Swarm Optimization is introduced to optimization design the operating conditions of the system. At design conditions, maximum net output power which is as the single-subjective optimized goal reaches 781.88 kW and the corresponding thermal efficiency and exergy efficiency achieves 12.96 % and 48.54 %, respectively. Meanwhile, thermodynamic properties in each state point of the system are calculated and compared with those of the basic Kalina cycle by selecting the evaporating pressure and the concentration of basic ammonia water as variables. The maximum net output power of the novel system is 111.92 kW more than that of the basic Kalina cycle, while the thermal and exergy efficiencies are also 1.07 % and 6.95 % higher at their respective design condition. In terms of exergy destruction, the evaporator and the condenser occupy the most parts of the system total exergy destruction. Comprehensively analyzing the system performance from the aspects of thermodynamic first and second laws, the proposed novel system has an excellent performance and a great potential to apply in the industrial field.