共查询到19条相似文献,搜索用时 140 毫秒
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地下水渗流对竖埋管换热器与岩土体的热量交换具有显著影响。该文应用地下水渗流理论和传热学理论,建立考虑热传导和地下水渗流共同作用的热渗耦合传热模型;针对南宁河流阶地土层,模拟分析地下水渗流对竖埋管换热器传热的影响。研究结果表明:1)地下水渗流可以强化地埋管的换热,且随着渗流速度的增大,强化换热作用越明显;2)地下水渗流对换热器热交换的影响具有方向性,在此基础上,对竖埋管换热合理的布置方式进行分析;3)南宁河流阶地地区,仅考虑砂砾层存在地下水渗流对换热的影响,更符合工程实际。 相似文献
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渗流对地下埋管换热器传热管间距的影响 总被引:1,自引:0,他引:1
为确定地下水渗流对土壤蓄冷与土壤耦合热泵集成系统中竖直地下管群换热器管间距的影响,本文基于热渗耦合作用下的数学模型,采用整体求解方法模拟了冬、夏季工况下管内流体、地下埋管换热器及周围土壤的温度场,分析了地下水渗流对其传热过程的影响。结果表明在冬夏工况下管间距宜不同,地下水运动对温度场的影响明显,而且地下水流速越高影响越大。 相似文献
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为确定地下水渗流对土壤蓄冷与土壤耦合热泵集成系统中竖直地下管群换热器管间距的影响,本文基于热渗耦合作用下的数学模型,采用整体求解方法模拟了冬、夏季工况下管内流体、地下埋管换热器及周围土壤的温度场,分析了地下水渗流对其传热过程的影响.结果表明在冬夏工况下管间距宜不同,地下水运动对温度场的影响明显,而且地下水流速越高影响越大. 相似文献
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地下水流动对地下管群换热器传热的影响分析 总被引:2,自引:1,他引:2
为确定地下水渗流对土壤蓄冷与土壤耦合热泵集成系统中竖直地下管群换热器的影响,该文基于热渗耦合作用下的数学模型,采用整体求解方法求得冬、夏季工况下管内流体、地下埋管换热器及周围土壤的温度场数值解,从而分析了地下水渗流对其传热过程的影响,结果表明地下水运动对原温度场的影响明显,而且越高的地下水流速影响越大。 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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地下含湿岩土热渗耦合模型及换热埋管周围土壤温度场数值模拟 总被引:2,自引:0,他引:2
考虑了地下水的渗流作用和U型换热埋管的实际形状,建立了U型管地下换热器管内流体以及周围土壤热渗耦合物理数学模型.模型将土壤视为均匀的、各向同性的饱和多孔介质,土壤中水的渗流视为二维.管内湍流流动采用Realizable k-ε模型,数值计算采用Fluent软件.给出了管内流体以及周围土壤的温度分布数值模拟结果,分析了土壤中水的渗流对传热过程的影响、U型管两支管的热短路作用及回填材料对土壤温度场的影响.所得结论对地下换热器的设计具有理论意义. 相似文献
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以埋设在均匀渗流介质中的螺旋埋管为研究对象,结合地源热泵工程应用背景,将地下螺旋埋管简化为连续的螺旋线热源,通过移动线热源理论与格林函数法,建立二维和三维非稳态的导热与对流联合作用的渗流传热问题的传热模型;求得无限长及有限长螺旋热源形态下渗流问题的温度响应的解析解。通过与纯导热模型的对比可知,地下水渗流会在一定程度上影响地下温度场的分布及传热达到稳态所需的时间。指出渗流速度是体现地下水流动对换热过程影响程度的重要参数,且渗流对整个螺旋管群的换热影响也被分析讨论。 相似文献
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为了确定地源热泵工程中地埋管换热器管群的最优排列方法和管间距,建立了热渗耦合下的地埋管换热器管群三维传热模型。利用Fluent软件通过数值方法模拟了不同排列方法、不同管间距下的换热器出水口温度,着重研究了存在地下水渗流时管群排列方法对换热能力的影响,并且提出了管群单位面积换热量这一评价指标。研究结果表明,叉排管群的换热能力要高于顺排管群,地下水的渗流作用使之更加明显。无论是叉排还是顺排,管群的换热能力都和地下水渗流方向密切相关。 相似文献
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A study on the performance of a geothermal heat exchanger under coupled heat conduction and groundwater advection 总被引:1,自引:0,他引:1
Being environmental friendly and with the potential of energy-efficiency, more and more ground-source heat pump (GSHP) systems are being widely used. However, the influence of groundwater advection on the performance of the geothermal heat exchanger (GHE) in a GSHP is not still clearly known. In this paper, the configuration of a vertical dual-function GHE used in an integrated soil cold storage and ground-source heat pump (ISCS&GSHP) system, which charged cold energy to soil at night and produced chilled water in daytime in summer, and hot water for heating in winter, is firstly presented. This is then followed by a report on a mathematical model for the GHE considering the impact of the coupled heat conduction and groundwater advection on the heat transfer between the GHE and its surrounding soil. The GHE model developed was then integrated into a previously developed simulation program for an ISCS&GSHP system, and the operating performances of the GHE in an ISCS&GSHP system having a vertical dual-function GHE have been studied by simulation and reported. These simulation results, firstly seen in open literature, are much helpful to the design of a GHE buried in soil and widely used in GSHP systems or ISCS&GSHP systems. 相似文献
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A two-region simulation model of vertical U-tube ground heat exchanger and its experimental verification 总被引:2,自引:0,他引:2
Heat transfer around vertical ground heat exchanger (GHE) is a common problem for the design and simulation of ground coupled heat pump (GCHP). In this paper, an updated two-region vertical U-tube GHE analytical model, which is fit for system dynamic simulation of GCHP, is proposed and developed. It divides the heat transfer region of GHE into two parts at the boundary of borehole wall, and the two regions are coupled by the temperature of borehole wall. Both steady and transient heat transfer method are used to analyze the heat transfer process inside and outside borehole, respectively. The transient borehole wall temperature is calculated for the soil region outside borehole by use of a variable heat flux cylindrical source model. As for the region inside borehole, considering the variation of fluid temperature along the borehole length and the heat interference between two adjacent legs of U-tube, a quasi-three dimensional steady-state heat transfer analytical model for the borehole is developed based on the element energy conservation. The implement process of the model used in the dynamic simulation of GCHPs is illuminated in detail and the application calculation example for it is also presented. The experimental validation on the model is performed in a solar-geothermal multifunctional heat pump experiment system with two vertical boreholes and each with a 30 m vertical 1 1/4 in nominal diameter HDPE single U-tube GHE, the results indicate that the calculated fluid outlet temperatures of GHE by the model are agreed well with the corresponding test data and the guess relative error is less than 6%. 相似文献
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Theoretical study on the performance of an integrated ground-source heat pump system in a whole year
Being environmental friendly and with the potential of energy-efficiency, ground-source heat pump (GSHP) systems are widely used. However, in southern China, there exists large difference between cooling load in summer and heating load in winter. Thus the increase of soil temperature gradually year-by-year will decrease the COP of the GSHP system. In this paper, the configuration of a vertical dual-function geothermal heat exchanger (GHE) used in an integrated soil cold storage and ground-source heat pump (ISCS&GSHP) system, which charged cold energy to the soil at night and produced chilled water at daytime in summer, and supplied hot water for heating in winter, is presented. This is then followed by reporting the development of the mathematical model for the GHE considering the impact of the coupled heat conduction and groundwater advection on the heat transfer between the GHE and its surrounding soil. The GHE model developed was then integrated with a water-source heat pump and a building energy simulation program together for a whole ISCS&GSHP system. Then the operation performance of the ISCS&GSHP system used for a demonstration building is studied. These simulation results indicated the system transferred 71.505% of the original power consumption at daytime to that at nighttime for the demonstration building. And the net energy exchange in the soil after one-year operation was only 2.28% of the total cold energy charged. Thus we can see the feasibility of the ISCS&GSHP system technically. 相似文献
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M. Piechowski 《国际能源研究杂志》1998,22(11):965-979
Validation of ground heat exchanger (GHE) model is presented using the experimental data obtained for both single and double pipe horizontal GHE. Sensitivity analysis of the GHE model shows the influence of the variation in the soil thermal conductivity, specific heat and density on the thermal performance of a GHE. Finally, the thermal performance of a GHE is analysed using both heat and mass transfer models, and conduction only model, as well as the influence of the initial soil moisture content on the thermal performance of a GHE. © 1998 John Wiley & Sons, Ltd. 相似文献
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为准确预测地埋管换热器在分层岩土中的传热特征,采用分离变量法和格林函数法,基于单个圆环热源基本传热单元问题的解答,建立考虑岩土结构分层和横观各项同性特征的地埋管传热解析模型。该模型适用于工程中常见的垂直钻孔和桩基埋管换热器分层传热问题,具有较好的普适性。以2层岩土为例,利用模型解答对分层岩土中地埋管的传热特征以及分层参数对其影响规律进行研究。结果表明:均匀介质假设计算误差随作用时间的增加而逐渐增大,在靠近热源处误差更加明显,预测地埋管长时间温度响应时,应采用分层传热模型;在临界区域范围内,可用均质假设模型预测地埋管的传热特性,均质等效热物性参数取为对应岩土分层的热物性参数值;分层岩土导热系数对地埋管传热性能影响较大,岩土平衡温度随分层导热系数比的增大而明显降低;地埋管长度和直径的比值对地埋管传热性能有所影响,岩土平衡温度随长径比的增大而升高,且其影响程度随分层导热系数比的减小而增强。 相似文献
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基于线热源理论的垂直U型埋管换热器传热模型的研究 总被引:15,自引:0,他引:15
基于经典常热流线热源理论,通过引入叠加原理、阶跃负荷及孔洞热阻思想将其发展为能够适用于变热流埋管换热与地源热泵系统模拟的变热流线热源模型,并与改进的经实验与理论验证的圆柱源理论模型进行了比较与分析。结果表明:所发展的变热流线热源模型能够有效地模拟地下埋管的换热过程,可作为地下垂直U埋管换热过程的计算模型,为地源热泵地下埋管换热器的设计计算及地源热泵系统的模拟提供了一种新的简单而又实用的计算方法。 相似文献