重庆某工程土壤源热泵地埋管换热器夏季间歇运行模式研究

发布时间：2018-05-14 13:44

本文选题：土壤源热泵 + 地埋管换热器　；参考：《重庆大学》2014年硕士论文

【摘要】：随着土壤源热泵的快速发展和广泛应用，在土壤源热泵系统多年运行过程中，其运行性能的变化情况成为人们关注的热点。随着系统连续运行，地埋管周围土壤的物理性质是固定的，热量持续不断的被土壤吸收或释放，地埋管周围土壤的温度场随时间持续变化，，造成地埋管换热器的换热性能不断下降，进而导致热泵系统性能的降低以及机组能耗的增加。土壤源热泵系统间歇运行是通过合理地控制热泵运行的时间，使土壤处于间歇蓄/放热状况，从而促使地埋管换热器周围土壤的温度场得到周期恢复，改善土壤的传热，增强地埋管换热器的换热能力，以及改善土壤源热泵系统的运行性能。但在实际工程中，热泵机组的启停比需要根据建筑实际负荷的特点来确定，具有一定的随机性。本文针对建筑的非满载负荷段，在满足建筑负荷的前提下，对土壤源热泵地埋管换热器进行夏季间歇运行模式的研究，该运行模式既满足建筑的负荷需求，又可以使土壤得到间歇恢复。本文以重庆某工程土壤源热泵系统为研究对象，建立实测系统，测试了实际运行下的地埋管换热器周围不同深度的土壤温度，分析了不同地埋管换热器周围土壤的恢复特性。利用fluent技术建立了地埋管换热器三维传热模型，并通过实测数据验证其合理性。根据实测数据分析总结出的地埋管换热器周围土壤的恢复规律，制定了土壤源热泵系统在非满载负荷段（0~25%，25~50，50~75%）下的不同地埋管管群运行模式。再模拟了原浆回填地埋管分别在不同负荷段、不同的间歇运行工况下的土壤温度分布情况及出口温度变化情况。通过对比不同运行模式对土壤温度分布的影响以及机组的能耗，得出不同非满载负荷工况下，相应的最佳运行模式。研究表明，各地埋管不同深度地温恢复情况大致相同。在前2天的恢复过程中，各测点的下降幅度较大。第1天的下降幅度占整个过渡季的58.15%~92.52%，第2天的下降幅度占整个过渡季的3.82%~11.93%，剩余时间段逐日各测点温度下降幅度随时间逐渐减缓，占整个过渡季的0.14%~5.42%。结合实际工程，针对3个管群制定了3种运行模式：运行模式1，一个管群运行，单个地埋管换热器以运行1天恢复2天为周期的重复运行；运行模式2，两个管群运行，单个地埋管换热器以运行2天恢复1天为周期的重复运行；运行模式3，所有管群运行，单个地埋管换热器均处于工作日。通过模拟分析，在同一建筑负荷段下，当地埋管换热器全开连续运行时，单个地埋管管内流量较小，土壤温度及地埋管出口温度的上升幅度也就较小。但恢复期较短，其逐日上升幅度较大，进而机组的能耗会越来越大。当地埋管换热器分群交替运行，单个地埋管换热器所需要承担的负荷不超过其满载运行时，单个地埋管管内流量较大，土壤温度及地埋管出口温度的上升幅度也就较大。但管群交替运行，其逐日上升幅度较小，进而机组的能耗上升幅度较小。当地埋管换热器分群交替运行，单个地埋管换热器所需要承担的负荷超过其满载运行时，需结合具体建筑负荷来确定地埋管换热器间歇运行是否合理。超出比额越大，其地埋管换热器间歇运行的意义越小。通过模拟分析，该工程在建筑负荷满载段前期，建筑负荷率为25%时，地埋管换热器间歇运行模式宜优先选择运行模式1；建筑负荷率为50%时，地埋管换热器间歇运行模式宜优先选择运行模式2；建筑负荷率为75%时，地埋管换热器间歇运行模式宜优先选择运行模式2。通过模拟分析，在建筑负荷满载段后期，建筑负荷率为75%时，地埋管换热器间歇运行模式宜优先选择运行模式2；建筑负荷率为50%时，地埋管换热器间歇运行模式宜优先选择运行模式1；建筑负荷率为25%时，地埋管换热器间歇运行模式宜优先选择运行模式1。
[Abstract]:With the rapid development and wide application of the soil source heat pump, the change of the performance of the soil source heat pump system has become a hot spot of attention. With the continuous operation of the system, the physical properties of the soil around the buried pipe are fixed. The soil is absorbed or released by the soil, and the soil around the buried pipe is the soil. The temperature field continuously changes with time, resulting in the decrease of heat transfer performance of the buried pipe heat exchanger and the decrease of the performance of the heat pump system and the increase of the energy consumption of the unit. The intermittent operation of the soil source heat pump system makes the soil in the intermittent storage / exothermic state by reasonable control of the time of the heat pump operation, thus promoting the heat transfer of the buried pipe. The temperature field around the soil is recovered periodically, the heat transfer of the soil is improved, the heat transfer capacity of the ground heat exchanger is enhanced, and the performance of the soil source heat pump system is improved. However, in the actual project, the start stop ratio of the heat pump unit needs to be determined according to the characteristics of the actual load of the building. In the non full load section, under the premise of satisfying the building load, the summer intermittent operation model of the soil source heat pump heat exchanger is studied. The model not only satisfies the load demand of the building, but also enables the soil to recover intermittently.
In this paper, the soil source heat pump system of a Chongqing project is used to establish the measured system. The soil temperature in different depths around the buried pipe heat exchanger under actual operation is tested and the soil recovery characteristics around the different buried pipe heat exchangers are analyzed. The three-dimensional heat transfer model of the buried pipe heat exchanger is established by using the fluent technology and the measurement is measured. The data is proved to be reasonable. According to the measured data, the restoration law of soil around the buried pipe heat exchanger is analyzed, and the operation mode of different buried pipe group under the non full load load section (0~25%, 25~50,50~75%) is formulated. The distribution of soil temperature and the change of the temperature of the outlet under the operating conditions are compared. By comparing the effects of different operating modes on the distribution of soil temperature and the energy consumption of the units, the corresponding optimal operation modes are obtained under different load conditions.
The study shows that the ground temperature recovery of different depths in different depths is approximately the same. During the first 2 days of recovery, the decrease of each test point is larger. The decrease of the first days is 58.15%~92.52% in the whole transition season, and the decrease of the second days is 3.82%~11.93% in the whole transition season. Gradually slowing down, accounting for the 0.14%~5.42%. combined with the actual project in the whole transition season, 3 operating modes are formulated for 3 tube groups: operation mode 1, a tube group running, a single buried tube heat exchanger to run for 2 days for 1 days, running mode 2, two tube groups running, and a single buried tube heat exchanger for 2 days to recover for 1 days. Cycle repetition operation; operation mode 3, all pipe groups running, and single ground heat exchangers are on working days.
Through the simulation analysis, under the same building load section, when the local pipe heat exchanger is running continuously, the flow of the single buried pipe is smaller, the soil temperature and the increase of the outlet temperature of the buried pipe are smaller. But the recovery period is shorter, and the increase of the energy consumption of the unit will become larger and larger. In alternate operation, the load required by a single buried tube heat exchanger is not more than its full load, the flow of the single buried pipe is larger, the temperature of the soil and the outlet temperature of the buried pipe are increased greatly. However, the daily rise of the pipe group is small and the energy consumption of the unit is small. When the load of a single buried tube heat exchanger is more than its full load, it is necessary to combine the concrete load to determine whether the intermittent operation of the buried pipe heat exchanger is reasonable. The greater the excess ratio, the smaller the significance of the intermittent operation of the buried pipe heat exchanger.
Through the simulation analysis, when the construction load rate is 25%, the intermittent operation mode of the buried pipe heat exchanger should choose the operation mode 1 when the building load rate is 25%. When the building load rate is 50%, the intermittent operation mode of the buried pipe heat exchanger should choose the operating mode 2 first; the ground heat exchanger is operated intermittently when the construction load rate is 75%. Patterns should be preferred to run mode 2.
Through the simulation analysis, when the building load rate is 75%, the intermittent operation mode of the buried pipe heat exchanger should choose the operation mode 2 when the building load rate is 75%. When the building load rate is 50%, the intermittent operation mode of the buried pipe heat exchanger should choose the operation mode 1 first; when the building load rate is 25%, the intermittent operation mode of the buried pipe heat exchanger is suitable. Priority selection operation mode 1.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU83

【参考文献】