中低温余热有机朗肯循环热经济性优化及实验研究

发布时间：2018-03-25 09:55

本文选题：有机朗肯循环　切入点：热经济性优化　出处：《哈尔滨工业大学》2016年博士论文

【摘要】：目前,日益增大的能源需求和严重的环境污染,迫切要求改变能源结构、节约利用传统能源和优化能源利用方式;同时,我国具有丰富的中低品位能源,如中低温余热能、太阳能和地热能等。作为一项理论成熟的中低温余热回收技术,有机朗肯循环(Organic Rankine cycle,ORC)具有结构简单,效率高和环境友好等优点。因此,利用有机朗肯循环高效回收中低品位余热,对提高我国的能源利用率和改善环境问题具有重要的意义。基于热力学第一定律和第二定律,构建了ORC的热力模型和经济模型,研究了系统运行参数对系统热力性能和经济性能的敏感度,基于排序法下的最佳经济性能,优选了适用于中低温热源的工质。结果表明考虑最佳经济性能的情况下,R11、R123和R245ca是比较适合于中低温余热的工质;综合考虑系统净输出功、热效率和?效率时,R142b和R114被认为在确保最佳经济性能下的优选工质。针对BORC(Basic organic Rankine cycle,BORC)和RORC(Regenerative organic rankine cycle,RORC)的热力模型和经济模型,研究了五种系统运行参数对两种循环的?效率和LEC(Levelized energy cost,LEC)的影响,并进行了基于最大?效率和最小LEC的双目标优化研究,进一步开展了最大?效率、最大净输出功和最小LEC的三目标优化研究。结果表明,改善系统热力性能会导致系统经济性能的恶化;通过对比双目标与单目标优化结果,发现较高的?效率和热效率必定伴随较低的净输出功和较差的经济性能;而较高经济性能可以保证较好的净输出功,然而?效率和热效率较低;双目标优化的帕累托最优解中和了热力性能和经济性能,因此,比较适合工程人员应用于工程决策问题。根据泡点温度和冷凝露点温度位置不同,提出了混合工质的四种工况,开展了四种工况的热经济性分析,并进一步对比了纯工质和混合工质的热经济性。研究结果表明,相比于纯工质,混合工质并不一定总是表现较好的热力性能和经济性能,主要取决于系统运行参数和混合工质质量分数;综合考虑分别以最大?效率和最小LEC的单目标优化结果,混合工质泡点温度位于相变结束点,露点温度位于相变起始点时,热力性能和经济性能最佳;对比混合工质和纯工质的帕累托最优解发现,相比于纯工质,混合工质表现出较好的热力学性能和几近同等的经济性能。建立了双ORC的热力模型,经济模型和环境评价模型,研究了顶部循环的蒸发温度,过热度,窄点温差,冷凝温度,以及底部循环的蒸发温度和冷凝温度对系统性能的影响,讨论了双ORC循环基于热力性能和经济性能的帕累托最优解,进一步探讨了双ORC循环热力性能、经济性能和环境性能的规律。基于TOPSIS工程决策法,分别得到了双ORC热经济性双目标优化和热环境三目标优化的帕累托最优解。基于3kW的中低温有机朗肯循环发电系统,实验测量分析了质量流量,过热度,膨胀机进口压力和工质泵进口压力对系统组件运行特性及系统性能的影响。研究了运行参数的敏感度,并通过修正工质泵和膨胀机的等熵效率和机械效率来对理论模型进行修正研究。实验对比了混合工质和纯工质的系统组件特性和性能。研究发现,质量流量的敏感度较大;修正模型比理论模型与实验测量的偏差值减小了67-84%;实验结果显示,混合工质的热效率和系统发电效率优于纯工质。
[Abstract]:At present, the increasing demand for energy and serious environmental pollution, urgent need to change the energy structure, the traditional way of using energy saving and optimization of energy; at the same time, China is rich in low grade energy, such as low temperature waste heat energy, solar energy and geothermal energy. As a theory of low temperature waste heat recovery technology is mature organic Rankine cycle (Organic, Rankine, cycle, ORC) has the advantages of simple structure, high efficiency and environmental friendly. Therefore, the use of organic Rankine cycle efficient recovery of low grade waste heat, it has important significance to improve China's energy utilization and environmental issues. The first and second laws of thermodynamics based on the construction of the heat the economic model and the model of ORC, studied the sensitivity of the system operation parameters on the thermal performance and the economic performance of the system, the best economic ranking method of based on optimized for The refrigerant in the low temperature heat source. The results show that considering the best economic performance in the case of R11, R123 and R245ca are more suitable for refrigerant in low temperature waste heat; considering the system net power output, thermal efficiency and efficiency, R142b? And R114 was considered in ensuring the best economic performance under the optimum medium. According to the BORC (Basic organic Rankine cycle, BORC) and RORC (Regenerative organic Rankine cycle, RORC) of the thermodynamic model and economic model, studied five kinds of system operation parameters on two cycle efficiency and LEC (Levelized energy? Cost, LEC) influence, and the study of double objective optimization based on maximum efficiency? And the minimum LEC, to carry out the maximum efficiency of three? Optimal maximum net power output and the minimum of LEC. The results show that the improved system thermal performance will deteriorate the system economic performance by double target; compared with the single objective optimization The results found that high? Efficiency and thermal efficiency must be accompanied by the economic performance of the net power output and poor low; and high economic performance can ensure that the net power output, better yet? Efficiency and low thermal efficiency; Pareto optimal solution and the thermal performance and economic performance, therefore, more suitable for Engineers used in engineering decision problem. According to the different bubble point temperature and condensation dew point position, put forward four kinds of conditions of mixed refrigerant, the thermal economic analysis of four conditions, and further compared with pure refrigerants and mixed refrigerant thermal economy. The results of the study show that, compared to pure. Matter, mixed refrigerant is not always better thermal performance and economic performance, mainly depends on the system parameters and the mixed refrigerant mass fraction; considering respectively with maximum efficiency and minimum? Single objective optimization LEC The mixed refrigerant bubble point temperature is located at the phase transition end point, the dew point temperature is located at the phase transition at the start point of thermodynamic performance and the best economic performance; comparison of mixed refrigerant and pure refrigerant Pareto optimal solution found that compared to the pure refrigerant, refrigerant mixture showed good thermodynamic and almost equal to economic performance. A thermodynamic model of double ORC, economic model and environment evaluation model of evaporation temperature, top cycle superheat, pinch point temperature, condensation temperature, evaporation temperature and condensation temperature and bottom cycle influence on system performance, discusses the double ORC loop Pareto optimal thermal performance and economic performance based on solution further, discusses the double ORC thermal performance, economic performance and environmental performance was studied. TOPSIS decision method based on the project are three objective optimization of double ORC thermal economy double objective optimization and thermal environment The Pareto optimal solution. 3kW in low-temperature organic Rankine cycle power generation system based on experimental measurement and analysis of the mass flow, superheat, effect of expander inlet pressure and refrigerant pump inlet pressure on the performance and operation characteristics of system components. The effects of the operating parameters of sensitivity, and by modifying the refrigerant pump and expander the isentropic efficiency and the mechanical efficiency of modified research on theoretical model. Comparison of the components of the system characteristics and performance of mixed refrigerant and pure refrigerant. The study found that the mass flow is more sensitive than the error correction model; theoretical model and experimental value is reduced by 67-84%; the experimental results show that the mixed refrigerant the thermal efficiency and power efficiency is higher than that of pure refrigerants.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TK115

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