中低温余热驱动的正逆耦合循环系统集成研究

发布时间：2017-12-28 00:32

本文关键词：中低温余热驱动的正逆耦合循环系统集成研究　出处：《中国科学院工程热物理研究所》2017年博士论文　论文类型：学位论文

【摘要】：随着我国能源消费需求持续增长和环境污染等问题日益严重,高效回收利用工业生产和生活中的余热已经成为我国节能减排的重要举措。本文依托国家重点基础研究发展计划(973计划)、国家自然科学基金和国家科技支撑计划等项目,围绕中低温余热驱动的正逆耦合循环系统开展研究,探索了中低温余热利用的新方法,从关键过程能量转换机理、系统集成和实验验证等方面开展了研究。在正逆耦合循环中,吸收-发生构成的热压缩过程是实现工业余热,特别是低温余热梯级利用的重要途径。通过深入分析热压缩过程,提出了以增压率作为特征参数的热压缩过程模型。增压率作为一个无量纲参数,表征了热压缩过程实际升压占极限升压的比例。探究了热压缩过程对低温余热的能量转化机理和热压缩过程的热力学特性规律,发现增压率作为特征参数可有效简化热压缩过程的设计和参数优化。进一步提出了热压缩过程在正逆耦合循环中的集成方式,研究了热压缩与机械压缩耦合的热力学性能及规律,为正逆耦合循环系统集成奠定了理论基础。通过将热压缩过程与机械压缩机进行耦合,实现了正逆循环间的热能和机械功的双重耦合,构建了中、低温余热互补利用的功冷联产系统。中温热源通过混合工质动力循环转换为机械功,低温热源通过热压缩过程和机械压缩过程耦合完成制冷,机械压缩耗功由混合工质透平提供。该系统不仅能高效回收内燃机烟气余热,为解决动力余热利用过程中的温度断层难题提供技术方案,还能全部回收利用缸套水余热用于制取0℃以下的冷量。系统针对不同品位的热源通过采用了不同的回收利用方式以减少不可逆损失,具有较好的热力性能。经济性分析结果表明,该功冷联产系统具备较好的经济效益和推广价值。研究了一种回收透平排气有效成分的新型开式功冷联产系统,探索了提高有效成分回收潜力的新方法。该系统中透平排气携带的较高温冷凝热在再沸器中为精馏过程提供热负荷,较低温冷凝热用于预热精馏塔进料;透平排气经过降温后形成的气液两相混合物中,气相组分的有效成分(制冷剂)浓度与透平排气相比明显提高,适合在制冷中回收利用。新型开式功冷联产系统验证了正、逆循环间物质耦合的有益效果,为正逆循环耦合提供了新思路。根据中低温余热的梯级利用机理,高品位热能通过动力循环转换为功,低品位热能通过热压缩过程用于提高气态工质压力。将热压缩过程与机械压缩机相结合,并用动力循环的输出功驱动机械压缩机,构建并研究了两种新型低温制冷系统。两种系统的区别在于热压缩过程与机械压缩机的耦合分别采用了复叠和复合两种形式。对比研究结果表明,复合式低温制冷具有更优的热力性能。节能机理分析结果表明,在逆循环中引入机械压缩过程解决了制冷温度过低导致热压缩过程性能急剧恶化的问题;同时,在热源与吸收式制冷循环之间构建混合工质动力循环,减少了热源与循环工质的换热温差,实现了余热的梯级利用,降低了系统的不可逆损失。通过对系统的热力性能进行敏感性分析,为系统进一步优化指明了方向。研制了中低温动力余热驱动的功冷联产系统实验平台。该实验平台主机由氨水蒸气发生子系统、透平膨胀作功子系统和氨水吸收式制冷子系统构成,系统设计发电功率为20 kW,制冷量为40 kW。配套的辅助实验系统包括烟气发生子系统、冷量输出子系统、冷却水循环子系统、数据监测与采集子系统、安全防护子系统等。通过氨水混合工质发电性能实验和氨水吸收式制冷性能实验研究探索了实验平台各子系统的运行特性,为后期进一步开展功冷联产系统性能实验和变工况实验奠定了基础。
[Abstract]:As China's energy consumption demand continues to grow and environmental pollution is becoming more and more serious, efficient recycling of waste heat from industrial production and life has become an important measure for energy saving and emission reduction in China. Based on the national key basic research and development program (973 Program), National Natural Science Foundation and the national science and technology support program project, drive around the middle and low temperature waste heat coupling inverse circulation system to carry out research, to explore a new method of low temperature waste heat utilization, carry out research from the key process of energy conversion mechanism, system integration and test verification etc.. In the positive and inverse coupling cycle, the thermal compression process composed of absorption and occurrence is an important way to realize industrial waste heat, especially the cascade utilization of low temperature waste heat. Through the deep analysis of the thermal compression process, a thermal compression process model is proposed, which takes the supercharging rate as the characteristic parameter. As a dimensionless parameter, the turbocharging rate represents the proportion of the actual rising pressure in the thermal compression process to the limit lift. The energy transformation mechanism and the thermodynamic characteristics of hot compression process in the process of hot compression are explored. It is found that the design and parameter optimization of heat compression process can be simplified effectively by using the supercharging rate as the characteristic parameter. The integration mode of hot compression process in positive and negative coupling cycle is further presented. The thermodynamic properties and laws of thermal compression and mechanical compression coupling are studied, which lays a theoretical foundation for the integration of positive and negative coupled cycle system. By coupling the thermal compression process with the mechanical compressor, we achieve the dual coupling between thermal energy and mechanical work between the positive and negative cycles, and build a power cooling co production system with complementary utilization of medium and low temperature waste heat. The temperature heat source through the mixed refrigerant cycle is converted to mechanical power, low temperature heat source by hot compression process and mechanical compression process coupling complete refrigeration, mechanical compression work provided by the mixed refrigerant turbine. The system can not only efficiently recover the residual heat from the internal combustion engine flue gas, but also provide technical solutions for solving the temperature and fault problems in the process of power waste heat utilization, and it can also recycle the residual heat from cylinder liner to produce the cooling capacity below 0 degrees. The system can reduce the irreversible loss by using different recycling methods for different grade heat sources, and it has better thermal performance. The result of economic analysis shows that the power cooling system has good economic and promotion value. A new open type active cooling system for recovery of the effective components of the turbine exhaust is studied, and a new method to improve the recovery potential of the effective components is explored. This system carry high temperature turbine exhaust condensing heat in the reboiler of distillation process with heat load, low temperature condensation heat to preheat the feed to the column; the gas-liquid mixture is formed after cooling the turbine exhaust gas phase, the effective components group of points (refrigerant) concentration and turbine exhaust was higher than suitable for use in refrigeration, recovery. The new open type power cooling system validates the beneficial effect of the coupling between the positive and the reverse circulation, and provides a new idea for the positive and reverse cycle coupling. According to the cascade utilization mechanism of medium and low temperature waste heat, the high grade heat energy is converted into power through power cycle. Low grade heat energy is used to improve gas working pressure by hot compression process. Two new cryogenic refrigerating systems are constructed and studied by combining the thermal compression process with the mechanical compressor and driving the mechanical compressor with the output power of the dynamic cycle. The difference between the two systems is that the thermal compression process and the coupling of the mechanical compressor are used in two forms of overlapping and recombination respectively. The results of comparative study show that the composite cryogenic refrigeration has better thermal performance. Energy saving mechanism in the inverse analysis results show that the compression process is introduced to solve the mechanical cycle refrigeration temperature too low and cause a sharp deterioration in the performance of hot compression process; at the same time, the absorption refrigeration cycle with mixed refrigerant cycle construction heat, reduce the temperature difference and heat circulation medium, the waste heat cascade utilization and reduce the irreversible loss. Through the sensitivity analysis of the thermodynamic performance of the system, the direction is pointed out for the further optimization of the system. The experimental platform of the power cooling co production system driven by the medium and low temperature power waste heat is developed. The experimental platform is made up of ammonia steam generation subsystem, turbine expansion power subsystem and ammonia water absorption refrigeration subsystem. The power generation system is designed to be 20 kW and the cooling capacity is 40 kW. The auxiliary experimental system includes flue gas generation subsystem, cold output subsystem, cooling water circulation subsystem, data monitoring and acquisition subsystem, safety protection subsystem and so on. The operation characteristics of each subsystem of the experimental platform were explored through ammonia power mixture performance test and ammonia water absorption refrigeration performance experiment, which laid the foundation for further developing the performance test and variable condition experiment of the power cooling co production system.
【学位授予单位】：中国科学院工程热物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TK115

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