村镇级生物质燃气冷热电联产系统能量品位耦合机理及协同优化研究

The combined cooling heating and power (CCHP) system based on biogas in village level can make full use of livestock manure, fruit and vegetable waste, kitchen disposal and crop straw to produce biogas efficiently by the anaerobic fermentation technology. Combining the cogeneration, low-temperature waste heat driven refrigeration and air-source heat pump technologies, the proposed system can completely supply cooling heating power and biogas, solve the multi-level demands in the village and reduce pollutant emissions significantly. The all-operation model and collaborative optimization model are built and verified by experiment. The annual thermal performance will be obtained, and the multi-dimensional evaluation methodology can be established. The energy grade coupling and integrated control mechanisms between supply, accumulation, consumption and control of energy are analyzed for multi-energy and multi-mass system. The energy supply characteristics of integration, reconfiguration and separation are revealed. The optimized structural parameters and control strategy will be achieved simultaneously by collaborative optimization method. It can provide theoretical basis for the population and application of the system in China. The achievements of the research can help to build the distributed power system on the basis of local resources, satisfy the basic energy demand, and promote the construction of the beautiful countryside.

村镇级生物质燃气冷热电联产系统可充分利用禽畜粪便、果蔬废弃物、餐厨垃圾、农作物秸秆等废弃物资源，通过生物质恒温厌氧发酵技术高效生产沼气，有效结合内燃机热电联产、低温余热制冷、空气源热泵等技术进行能量梯级利用，大幅减少污染物排放，实现冷、热、电、气四联供，完全解决村镇居民多层次用能需求。本项目以系统全工况动态模型和协同优化模型建立与试验验证为基础，获取系统全年时变性能，构建系统多维度评价方法与体系；研究针对多能流、多物质流的供-蓄-用-控间的能量品位耦合与一体化调控机制，揭示能量集成、整合、分离的对口供能特性；在全年时域宽度和地域广度上，通过系统协同优化研究同步获得系统最优配置及运行策略，为系统规模化推广应用提供理论依据。本项目的研究成果有助于建成以村镇自有资源为基础的分布式供能系统，解决村镇基本用能需求，推动我国美丽村镇建设。

基于可再生能源的冷热电联产系统具有能源供应形式多样化、能量转换高效、能源供应清洁等优点，在我国实现“双碳”目标的历史大背景下具有巨大的发展潜力。村镇级生物质燃气冷热电联产系统由诸多类型的设备构成，设备间相互依存与影响，一旦配置不当或运行策略不佳，将直接导致设备的效率过低，影响系统经济性能。本项目建立系统全工况数学模型，构建基于基础指标、核心指标、外围指标的多属性综合评价体系，建立基于时间、空间维度的系统配置及运行控制协同优化理论与方法，并以甘肃省兰州市典型住宅为应用案例，多角度探索系统中关键过程的能量传递与转换规律、能量品位耦合特性、系统最优配置与运行策略。.基于系统多属性综合评价体系，将供能系统与村镇建筑相结合，探究了室内热环境舒适度与空气源热泵系统能耗的优化平衡点，在间歇运行模式下室内温度和水箱水温分别控制在14-16℃和38℃时，系统的供暖能耗降低了78.6%，室内热舒适满意度提高了31.03%。进而将多目标智能优化算法与主客观相结合的优化结果求解技术有效结合，充分考虑需求侧约束、能量平衡约束、系统运行约束，以一次能源节约率、二氧化碳减排率及费用年值节省率为目标函数，以主要设备容量为决策变量，开展系统配置及运行优化研究。优化后系统综合性能得到稳步提升，在无太阳能介入时，生物质能占比由优化前的78.17%增至85.61%，综合性能指标值由优化前的39.2%增至42.7%。在耦合太阳能光伏发电时，系统的主要环境效益指标由75.90%增加到82.53%，费用年值节省率由32.58%降低到31.74%，热力性能指标由10.24%增加到12.42%，系统综合性能指标较优化前提升了3.64%。同时，系统实际性能和优化结果受到系统成本参数、运行参数和技术参数的动态影响，存在典型的地域性差异及时变特性。本项目的研究成果有助于建成以可再生能源为基础的综合能源系统，解决冷热电气等基本用能需求，推动我国能源低碳转型，赋能全社会减碳可持续发展。