大庆地区太阳能—土壤源热泵系统模拟研究

发布时间：2018-05-02 09:38

本文选题：太阳能 + 土壤源热泵　；参考：《东北石油大学》2017年硕士论文

【摘要】：作为重要的可再生能源,太阳能和地热能受到广泛的重视。我国严寒地区供暖时间长,供暖消耗的一次性能源多。因此,研究可再生能源在供热领域的应用有着重要的意义。以大庆为例,大庆地广人稀,全面铺设热网不利于节能环保,很适合利用太阳能-土壤源热泵系统来实现供暖需求。本文主要研究工作及成果:(1)介绍了太阳能系统中集热器的形式和集热面积的计算公式,利用实验台的测试结果,对集热面积公式进行简化。分析地埋管换热器的传热原理和土壤的蓄热特性。(2)结合大庆地区土壤类型和特点,建立垂直U型管三维换热器模型。并根据实验数据与数值模拟结果相对比,验证所建模型符合实际工程。(3)对单根U型管换热器而言,在有渗流的情况下,模拟分析了进口流速、进口水温、回填材料及管材对单位管长换热量的影响。模拟发现出口的温度随流速的增加而增加,外径为32mm的PE管,管内流速经济合理的选择是0.4m/s~0.8m/s;地埋管换热器进口的温度逐渐增大时,其出口的温度也逐渐增大,单位管长换热量的变化曲线,呈现出线性上升趋势。回填材料尽量使用原土回填。若原土回填成本高,为提高换热量可以增加回填材料的导热系数。同理选择埋管管材时,也应尽可能选择导热系数大的。分析渗流层不同对出口水温的影响时发现,与无渗流层相比有渗流层时的出口温度比较低,渗流有利于提高埋管换热器的换热效率。渗流发生在不同的土壤层,出口温度也不同,在第二层时出口温度最低。(4)对管群换热器进行周期性模拟,根据土壤温度变化分析埋管间距、蓄热温度、蓄热时间、埋管排列方式对地下土壤温度场的影响。无蓄热时,埋管间距越大,换热井间的影响越小,越有利于换热。此种工况下多边形排列优于交叉排列和顺序排列。无蓄热连续运行时,埋管换热器效率降低,应引进蓄热工况。蓄热工况下运行时发现:埋管间距越小,温度升高速率越快;蓄热时,多边形排列取热后的冷量汇集在多边形内部并向中心集中,由于热量阻隔,使其不能释放到周围及更远的地方,蓄热效果也远不如其他方式。
[Abstract]:As an important renewable energy, solar energy and geothermal energy are paid more and more attention. Our country cold area heating time is long, the heating consumes the one-time energy more. Therefore, it is of great significance to study the application of renewable energy in the field of heating. Taking Daqing as an example, it is not good for energy saving and environmental protection to lay heat network in Daqing, so it is suitable to use solar-ground source heat pump system to meet heating demand. This paper mainly introduces the form of collector and the calculation formula of collector area in solar energy system, and simplifies the formula of collector area by using the test results of the test bench. Based on the analysis of heat transfer principle and soil heat storage characteristics of buried tube heat exchanger in Daqing area, a vertical U-tube three-dimensional heat exchanger model is established. According to the comparison between experimental data and numerical simulation results, it is verified that the model is in accordance with the actual project. For a single U-tube heat exchanger, the inlet velocity and inlet water temperature are simulated and analyzed under the condition of seepage. The effect of backfill material and pipe material on heat transfer of unit pipe length. The simulation results show that the outlet temperature increases with the increase of flow velocity, and the outlet temperature of PE pipe with outer diameter of 32mm is 0.4m / s / s and 0.8m / s respectively. When the inlet temperature of underground tube heat exchanger increases gradually, the outlet temperature increases gradually. The heat transfer curve of unit length shows a linear upward trend. The backfill material should be backfilled with the original soil as far as possible. If the backfill cost of the original soil is high, the heat conductivity of the backfill material can be increased in order to increase the heat transfer. In the same way, when the buried pipe is selected, the heat conductivity should be as large as possible. By analyzing the influence of seepage layer on outlet water temperature, it is found that the outlet temperature of seepage layer is lower than that of non-seepage layer, and seepage is beneficial to improve the heat transfer efficiency of buried tube heat exchanger. Seepage occurs in different soil layers and outlet temperature is also different. In the second layer, the outlet temperature is the lowest. (4) the tube group heat exchanger is periodically simulated. According to the change of soil temperature, the distance between buried tubes, heat storage temperature, heat storage time are analyzed. The influence of the arrangement of buried pipes on the temperature field of underground soil. When there is no heat storage, the larger the buried pipe spacing, the smaller the influence of heat transfer between wells, which is more favorable to heat transfer. In this case, polygon arrangement is superior to cross arrangement and sequential arrangement. Without heat storage, the efficiency of buried tube heat exchanger is reduced, so the heat storage condition should be introduced. Under the condition of heat storage, it is found that the smaller the distance between buried tubes is, the faster the rate of temperature rise, and when the temperature is stored, the cooling amount arranged by polygon is concentrated in the polygon and concentrated to the center, because of the heat barrier, It can not be released to the surrounding and further places, heat storage effect is far less effective than other ways.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU83;TU18

【参考文献】