基于运行阶段土壤热承载力的大规模地源热泵设计方法重构

Large-scale ground source heat pump system (LSGSHPS) has been developed and widely used in China. However, existing design theory does not cover system reliability and ground thermal capacity around the buried pile cluster of LSGSHPS. First, we propose to analyze a series of typical scenarios with different building load characteristics in different regions. Second, the reasonable threshold range of the design soil temperature can be determined by theoretical calculations, and a prediction model, which is based on Resistor-capacitor model, can be built to determine the dynamic temperature changes of the surrounding soil. Using the cross-linked analysis of energy efficiency and heat exchange attenuation surrounding the pipes, the effective depth and borehole distance is calculated with various heat fluxes, the effects of different pile cluster temperature change characteristics and additional heat capacity-thermal resistance are analyzed for the reliability of LSGSHPS system. Third, the upper threshold of thermal capacity for the finite soil around pile cluster in LSGSHPS system can be calculated based on thermodynamics and experimental data. According to the temperature distribution of soil around the buried pile cluster and the setting reliability level of system, the evaluation indicators of thermal capacity and monitoring method can also be discussed. By conducting the research, the design parameters of LSGSHPS can be optimized based on the heat transfer characteristics of the soil，and a design method can be presented to better support application of the LSGSHPS.

针对现有设计理论没有反映大规模地源热泵可靠性和土壤热承载力等不足，本项目对不同气候区、建筑负荷特性的典型场景，提出根据设定的不同可靠性和经济性水平，确定土壤设计计算温度选取原则及合理的阈值范围，并建立基于阻—容模型的埋地管群周边岩土体动态温度变化预测模型；对大规模地源热泵系统埋地管群近壁处换热量衰减与能效进行关联分析，分析不同负荷强度对应的埋管有效深度、合理管间距，得到不同设计管群布置方式的温变特性与热容附加热阻对大规模地源热泵系统可靠性的影响；根据热力学原理与实验测试数据，分析计算得到大规模地源热泵系统埋地管群岩土体的热承载力限值，根据埋地管群周围岩土体的温度分布特征及设定的可靠性水平，探讨了大规模地源热泵系统热承载力的评价指标与监控方法。根据上述研究成果，对基于埋地管群土壤传热限值的大规模地源热泵系统的设计参数进行优化，形成有理论研究成果与基础数据支撑的大规模地源热泵设计理论。

完成研究：用于动态热特征分析的热物性参数计算方法；不同典型气候区、土壤类型及建筑负荷特性对应的土壤设计计算温度与系统可靠性水平的关联分析；节能性和经济性的多因素敏感性分析；土壤计算温度确定原则与阈值范围。基于阻-容模型的埋地管群周边岩土体动态温度变化的预测模型；间歇运行时近壁处岩土体恢复特性；基于埋地管群换热强度变化的热泵机组参数匹配与优化；运行阶段管群换热量衰减与机组运行能效的关联性分析；间歇运行管群换热量波动对热泵系统出力及能耗的计算方法。地管群岩土体热承载力评价指标与计算方法；地埋管群岩土体热承载力监控方法、提高岩土体热承载力的地埋管群布置方式、岩土体热承载力对热泵系统总取放热量限值。基于土壤热承载力限值的热泵系统最大出力的限值；热泵运行参数与竖直埋管有效深度、合理管间距的确定原则；地埋管换热强度与土壤热物性参数、运行时间及运行方式的关联性；运行阶段埋管换热量衰减与设计管内循环流体经济流速范围。