单级闪蒸-卡琳娜循环发电热力学性能分析与优化

Analysis and optimization of thermodynamic performance of single flash-Kalina cycle in power generation

在卡琳娜循环的基础上,根据梯级用能理论开发单级地热闪蒸-卡琳娜循环技术,分析循环工质的热力学物性,确定系统关键运行参数并建立热力学性能评价指标。基于Peng-Robinson状态方程,借助Aspen HYSYS软件,在氨质量分数为48%、50%和52%时对系统的热效率和?效率进行基于遗传算法(Genetic Algorithm)的单目标优化和带精英保留策略的非支配排序遗传算法(Elitist Non-dominated Sorting in Genetic Algorithm)的多目标优化。热力学分析结果表明,氨水混合物蒸发压力、液化天然气(LNG)气化压力、天然气输送压力、地热水蒸发压力和氨质量分数对系统热力学性能影响较大;单目标优化结果显示,系统在氨质量分数为52%时获得的最大热效率为34.46%,最大?效率为50.65%,较优化前分别提高了12.47%和3.43%;采用LINMAP决策方法从多目标优化结果中搜索获得的系统最优热效率为32.14%、?效率为45.31%,对应的氨水混合物蒸发压力、LNG气化压力、天然气输送压力、地热水蒸发压力和氨质量分数分别为1 627.80 kPa、3 232.85 kPa、503.40 kPa、582.55 kPa和52%。

Based on the Kalina cycle,a single-stage geothermal flash-Kalina cycle was proposed,incorporating the principles of cascade utilization theory.By analyzing the thermodynamic properties of the working fluid in the cycle,the system's crucial operating parameters were determined,and thermodynamic performance evaluation metrics were established.Utilizing the Peng-Robinson state equation and employing software of Aspen HYSYS,the system's thermal efficiency and exergy efficiency were optimized using single-objective optimization based on the genetic algorithm(GA) and multi-objective optimization based on NSGA-Ⅱ for ammonia mass fractions of 48%,50%,and 52%.Thermodynamic analysis results revealed that the evaporation pressure of the ammonia-water mixture,LNG gasification pressure,natural gas transmission pressure,geothermal water evaporation pressure,and ammonia mass fraction had a significant impact on the system's thermodynamic performance.The single-objective optimization results indicated that the maximum thermal efficiency achieved at an ammonia mass fraction of 52% was 34.46%,with a maximum exergy efficiency of 50.65%,representing improvements of 12.47% and 3.43%,respectively,compared to the initial optimization.Employing the LINMAP decision method,the system's optimal thermal efficiency was found to be 32.14%,with an exergy efficiency of 45.31%.The corresponding values for the ammonia-water mixture evaporation pressure,LNG gasification pressure,natural gas transmission pressure,geothermal water evaporation pressure,and ammonia mass fraction were 1 627.80 kPa,3 232.85 kPa,503.40 kPa,582.55 kPa,and 52%,respectively.