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土壤源热泵地下水平埋管换热性能及其周围土壤温度场的影响研究 总被引:4,自引:0,他引:4
通过建立地下水平埋管换热器模型,模拟了土壤导热系数对埋管及其周围土壤温度场分布和埋管换热量的影响.分析了埋管管材及埋管埋深、管径、管壁厚度等对埋管换热的影响.模拟结果显示,当土壤导热系数从1.1W/(m·℃)增大到2.5W/(m·℃)时,埋管单位管长换热量增幅达100.8%,且到埋管距离越近的点,其土壤温度随土壤导热系数的变化相对较快.地下二层埋管外表面温度及其周围土壤温度变化比地下一层换热稳定性好,换热量大.适当的加大管径,减小管壁厚,有利于增强埋管换热. 相似文献
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建立了水平埋管的三维数学模型,使用Fluent软件详细模拟了冬夏季工况下水平埋管及其周围土壤温度场的分布规律。通过文献中的实验数据对算法进行验证,证明该模型算法具有可靠性。 相似文献
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多钻孔竖直U型埋管换热器传热研究 总被引:1,自引:0,他引:1
以地源热泵地下U型埋管四钻孔换热器为研究对象,利用有限元计算方法,编制程序,模拟分析了系统运行时间及钻孔顺序排列和交叉排列时钻孔间距和布置形式对土壤温度场的影响。结果表明:随着运行时间的增长,热干扰现象越强烈,热干扰主要发生在钻孔之间,在两钻孔中间影响最大;从土壤能源利用均衡性角度来讲钻孔交叉排列的形式优于顺序排列的形式。 相似文献
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为了确定渗流对竖直地埋管换热器换热性能的影响,基于多孔介质传热理论与Darcy定律,利用多物理场耦合软件COMSOL建立了三维热渗耦合模型,模拟了有无渗流条件下竖直地埋管换热器周围土壤温度场的变化。结果表明,地下水渗流有助于竖直地埋管换热器换热,且渗流速度越大,竖直地埋管换热器换热效果越明显;平行于渗流方向处温度场偏向下游,垂直于渗流方向处温度场始终保持对称分布,渗流速度由0m/s增大到1.0×10-5 m/s时,对应热作用半径由0.42m减小到0.32m。 相似文献
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文章搭建了土壤热湿迁移实验装置,并利用该装置研究了不同进口流体温度、土壤体积含水率条件下,地埋管换热器周围土壤温度场、湿度场的变化特性。分析结果表明:随着进口流体温度逐渐升高,土壤温度、湿度的最大值均逐渐升高,土壤温度、湿度的下降速率逐渐加快;土壤的初始体积含水率越大,热源对土壤温度的作用半径越大,当土壤的初始体积含水率分别为0%,35%时,热源对土壤温度的作用半径分别为280,380 mm;当土壤与地埋管之间的径向距离为0~225 mm时,土壤含水率主要受温度梯度的影响,随着该径向距离逐渐增加,土壤含水率逐渐升高,当土壤与地埋管之间的径向距离为225~380 mm时,土壤含水率会受到温度梯度与含水率梯度的共同作用,使得水分逐渐向热源方向逆向迁移,当土壤与地埋管之间的径向距离为225 mm时,土壤含水率出现峰值,当土壤与地埋管之间的径向距离大于380 mm时,温度梯度对土壤水分迁移的影响逐渐减弱,土壤含水率逐渐降低,当土壤与地埋管之间的径向距离为525 mm时,土壤含水率保持稳定。 相似文献
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Fouling is one of the main problems of heat transfer which can be described as the accumulation on the heat exchanger tubes, i.e.; ash deposits on the heat exchanger unit of the boiler. A decrease in heat transfer rate by this deposition causes loss in system efficiency and leads to increasing in operating and maintenance costs. This problem concerns with the coupling among conduction heat transfer mode between solid of different types, conjugate heat transfer at the interface of solid and fluid, and the conduction/convection heat transfer mode in the fluid which can not be solved analytically. In this paper, fouling effect on heat transfer around a cylinder in cross flow has been studied numerically by using conjugate heat transfer approach. Unlike other numerical techniques in existing literatures, an unstructured control volume finite element method (CVFEM) has been developed in this present work. The study deals with laminar flow where the Reynolds number is limited in the range that the flow field over the cylinder is laminar and steady. We concern the fouling shape as an eccentric annulus with constant thermal properties. The local heat transfer coefficient, temperature distribution and mean heat transfer coefficient along the fouling surface are given for concentric and eccentric cases. From the results, we have found that the heat transfer rate of cross-flow heat exchanger depends on the eccentricity and thermal conductivity ratio between the fouling material and fluid. The effect of eccentric is dominant in the region near the front stagnation point due to high temperature and velocity gradients. The mean Nusselt number varies in asymptotic fashion with the thermal conductivity ratio. Fluid Prandtl number has a prominent effect on the distribution of local Nusselt number and the temperature along the fouling surface. 相似文献
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H. A. Asghar 《国际能源研究杂志》1991,15(6):509-513
The paper addresses the problem of the estimation of ground losses from underground structures. Existing work has been limited to the cylinder and the sphere for steady state conditions. The numerical solution of the three-dimensional equations for time-dependent conditions requires a prohibitive amount of computing time. The present paper analyses a spherical underground structure with a periodic source at its centre and with periodic ground surface temperature. 相似文献
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. oas-sous tw con~ tot ed trsmeans of meving Pactri tal bo bo widsly nsed intw ot wet boal. ~ or not od,mp Of gaS aDd solid waSte hot and otherinMal tw. W bas the adVantage Of bo bedpem tw, cope edgUhaOn anu easr cootOf -al reshaCe tim diStritw (RTD in hedexChaDg over the fhadhal bo mfor. HOWeVer uP tohaX the -- on the hod transfer in thes kindOf bea tw are od feW to our We.McGa wt a two -ed hamch COnSistw Of pe -- l,], in which themoha ~ We was divital into man diotch an0 the bo o… 相似文献