【摘要】 基于有限元分析方法,建立套管式地埋管三维非稳态传热模型,利用自行搭建的套管式地埋管传热实验台实验验证了所建数理模型。数值模拟研究了回填材料、流体进出口方式、不同管径组合等工况下的套管式地埋管换热器传热特性。研究结果表明:实验与模拟结果的相对误差在10%以内,证明了所建立数理模型的合理性;导热系数和热扩散率大的回填材料能获得较高的单位井深换热量和较低的出口水温,热短路现象明显;相比外进内出的流动方式,内进外出的方式能获得更低的出口水温,但后者热短路现象更为严重;在套管换热器外管管径不变的条件下,增大内管管径可缓解热短路现象,提高换热器传热性能。更多还原

【Abstract】 Based on the finite element method,a three-dimensional unsteady heat transfer model of vertical double-pipe ground heat exchanger is established in this paper. The heat transfer experiments of vertical double-pipe ground heat exchanger were performed to validate the mathematical model. On this basis,the heat transfer characteristics of vertical double-pipe ground heat exchanger under the conditions of backfill materials,inlet and outlet modes of fluid,and combination of different pipe diameters were studiedby numerical simulation. The results show that the relative error between the experimental resultsand simulation results was less than 10%,which proves the rationality of the mathematical model. The higher average quantity of heat per meter and lower outlet water temperature were obtained through the use of backfill material with high thermal conductivity and thermal diffusivity,but the phenomenon of thermal short circuiting was more obvious atthe same time.Compared with the flow mode of inside out and outside in,lower outlet water temperature can be obtained and the phenomenon of thermal short circuiting was more obvious through the use of inside in and out mode. When the external diameter of double-pipe ground heat exchanger was constant,increasing the internal diameter can alleviate the thermal short circuiting phenomenon and improve the heat transfer performance of the heat exchanger.更多还原