【作者】 彭亮；

【导师】 卢军；

【作者基本信息】 重庆大学 ， 供热、供燃气、通风及空调工程， 2008， 硕士

【摘要】 随着人类使用能源越来越多,能源对人类经济社会发展的制约和对资源环境的影响也越来越明显。节能减排已经成为全球各国关注的焦点之一。地源热泵技术由于其具有显著的节能环保特性,正在受到人们的重视。本文根据上海某办公楼采用的地源热泵项目,对其系统的设计和运行情况进行了介绍和分析。根据DEST能耗模拟软件计算所得的建筑全年负荷,针对全部采用地源热泵制冷供热的方案和采用地源热泵+风冷冷水机组辅助供冷的方案进行比较。考虑到系统的初投资等原因,选择采用风冷冷水机组辅助供冷的复合式地源热泵系统。该办公楼地源热泵项目在地下埋管管壁贴附了Pt100A级铂电阻测温计进行逐时温度的测试。项目已经运行一年多,根据2007年5月份第一次开机到2008年5月开机这一个运行周期内的地温测试数据对该项目的换热器的运行情况进行分析。由于办公建筑仅在上班时间开启空调,地源热泵系统是间歇运行的。因此在夏季制冷季测试温度值呈“上升—下降—上升”波动形状,且当建筑负荷越大时,波动的幅度越大。随着系统运行,地下土壤平均温度逐渐增大,测点温度平均值最大达到29.5℃,最大单位孔深排热量达到53W/m。冬季供热季测试温度值呈“下降—上升—下降”波动形状,同样当建筑负荷越大时,波动幅度越大。地下土壤平均温度值随着系统运行逐渐减小,测点温度值最小达到11.9℃,最大单位孔深吸热量达到37 W/m。整个系统运行情况较好,基本达到设计要求。但是由于系统采用的是定流量设计,因此在制冷季初期末期和冬季常常出现“大流量,小温差”的情况,建议改造成变频水泵。针对部分负荷运行时间较多,可以施行地下埋管换热器分区轮换运行来增加系统的间歇运行时间,缓解土壤温度的变化。本文根据《地源热泵系统工程技术规范》和线热源数学模型,编制了地源热泵设计与模拟程序。实现了地源热泵地下埋管换热器的长度设计,钻孔壁土壤温度模拟和换热器进出水温度随建筑负荷逐时模拟的功能,同时可以通过计算热泵机组能耗,水泵能耗,辅助供冷能耗来计算系统能耗。并将前述办公楼工程中各项参数带入程序中进行计算,模拟结果良好,符合实测数据的变化规律。同时根据实际应用情况提出了程序进一步完善的方向。通过编制程序对影响地源热泵系统性能的参数进行研究,结果显示:在土壤、回填材料和管材等材料的热物性参数中,土壤和回填材料的热物性参数对系统性能影响最大,应该提高土壤的导热系数,回填材料的导热系数来提高系统性能,降低能耗。提高土壤的导热系数可以通过土壤洒水的方式,增加土壤中水分含量能有效提高系统能效,缓解土壤温度升高。且回填材料的导热系数采用2.0W/m℃是比较经济的。在对钻孔内热短路的影响因素分析中通过计算发现采用对钻孔内出口支管包裹保温层来增加管材的导热热阻是减小热短路影响的最有效措施。本文还针对前面提出的部分负荷下地下埋管换热器分区轮换运行的方式进行了分析计算,发现这种方式能够有效的缓解当系统连续运行时带来的土壤温度升高对系统造成的不利影响。当轮换的次数越频繁,换热器周围土壤温度变化越小。特别对于连续在部分负荷运行时间较长的系统,采用埋管换热器分区轮换运行的方式能够有效的提高系统性能。更多还原

【Abstract】 With the increasingly expense of energy by human beings, the impact of energy to the human economic, social, resource and environmental becomes more and more obvious. Energy reduction has become the focus of all countries concerned. Ground-source heat pump technology has been caught more and more attention due to its significant energy saving and environmental protection features.According to a ground-source heat pump project of a office building in Shanghai, this paper introduced and analyzed the design and performance of this project. Based on the building load calculated by the DEST simulation software, two programs were compared. One just uses the ground-source heat pump, another makes use of a ground-source heat pump and an air-cooled chiller as an auxiliary cooling equipment. Taking the system’s initial investment into account, we chose the composite ground-source heat pump program.In this project, the Pt100A level PRTs were attached in the pipe wall in order to test the temperature changing. The paper analyzed the heat exchanger performance according to the temperature data in a operation cycle from may 2007 to may 2008. The ground-source heat pump system was operating intermittently because of the characteristic of the heat load in the office building. In the summer, the temperature fluctuated. And when the building load became bigger, so is the extent of the fluctuations. As the running of the system, the average soil temperature increased. The average maximum temperature reached 29.5℃, the largest capacity of single-hole reached 53W / m. In winter, the temperature fluctuated as well. As the operation of the system, the average soil temperature reduced. The average minimum temperature drop to 11.9℃, the largest capacity of single-hole fell to 37W/m. The system was running well, it met the design requirements. However, because the constant water system, it often appeared that“big flow but small temperature difference”in the early and end of the cooling season as well as heating season, the author suggests that it be changed into variable water system. For the system usually runs in partial load, the rotatable operation of heat exchanger was been proposed. In this rotatable operation, it can extend the time for the resumption of the soil and ease the change of the soil temperature.In this paper, the author developed a ground-source heat pump system and simulation program according to the Technical code for ground-source heat pump system and one-dimensional line-source model. The program achieved the function of the length design of the heat exchanger under the ground, simulation of the soil temperature and the water temperature in and out of the exchanger. And it also can calculate the system energy consumption by referring to the heat pump unit consumption, water pump consumption, and auxiliary cooling system consumption. When we put the parameters of the office building project into the program, the calculate result well matches the measured data. At the same time, we put forward to further improvement of the process according to the actual application of this program.By studying on factors effect on the performance of underground heat exchanger by the program, the results indicated that the thermal properties of soil and the backfill material have the largest impact on the performance of the system. We should increase the heat conductivity of the soil and the backfill material to reduce the energy consumption. Increasing the soil moisture content by watering the soil can reduce the rise of the soil temperature and energy consumption effectively. The heat conductivity of the backfill material with the conductivity of 2.0W/m℃is economical. When studying the influence factor of the heat short-circuit in drill, it showed that wrap insulation on the out water pipes is the most effective measures to reduce the negative impact of the heat short-circuit.In the end, the paper analyzed the rotatable operation of heat exchanger. It found that this operation can alleviate the negative impact of soil temperature rise because of the long time running of the system. And when rotate more frequently, the smaller the change of the siol temperature. Particular for some project usually running in partial load for a long time, using the rotatable operation of heat exchanger is an effective way to improve system performance.更多还原