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岩土导热系数是地源热泵地埋管换热器的重要设计参数;测井单位深度换热量是地埋管换热器系统的设计依据。掌握工程区域岩土的热物性及换热性能,是保证地源热泵系统高效、稳定运行的关键。文章建立了现场测试岩土导热系数及换热量的方法,并结合沈阳浑南高新技术产业开发区某地源热泵工程,测试分析了岩土导热系数和测井单位深度换热量。结果表明,该区域的岩土具有较好的导热能力,适合采用地埋管地源热泵系统;在特殊地理条件下设计地源热泵系统方案前,应对拟建区域的地质条件进行全面勘探,以优选工程区域,为岩土热响应测试结果的可靠性提供保障。 相似文献
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通过原位热响应试验数据验证了TRNSYS软件中U型地埋管换热器模块Type557计算模型的可靠性,应用TRNSYS软件建立地埋管换热模型。基于正交试验的研究方法,综合分析了埋管壁、回填材料、埋管周围岩土的导热系数对埋管换热器换热效果的影响规律。得到影响地埋管换热过程的最主要因素是岩土导热系数,回填料导热系数对其影响程度略低于岩土导热系数,埋管壁导热系数对其影响不大的结论。 相似文献
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由于取样的扰动和室内试验方法的局限性,用岩土样品导热系数代表岩土层原位有效导热系数存在明显误差。基于"杭州市浅层地温能调查评价项目"中40个热响应试验孔的地层结构和现场热响应试验成果,用多元线性回归分析理论和行业数据统计SPSS软件(statistical product and service solutions)程序,以各岩土层厚度为自变量、原位有效导热系数为回归系数,热响应试验所确定的试验孔岩土的综合导热系数为因变量,确定各岩土层的原位有效导热系数,回归方程和回归系数显著可信,可用于计算统计区域内其他地埋管热交换工程孔岩土的综合导热系数。 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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《Applied Thermal Engineering》2007,27(2-3):430-441
This paper presents the results of experimental measurement and numerical simulation of the performance of a heat pump system designed to make use of rainwater and ground as heat sources/sinks. The system was tested under laboratory conditions. A refrigerant was circulated through a closed loop heat exchanger to transfer heat between the heat pump and rainwater in a storage tank and another heat exchanger made of solid bars or heat pipes to transfer heat between the stored rainwater and surrounding soil. Physical and thermal properties of soil such as water content, density, specific heat, thermal diffusivity and thermal conductivity were determined. Numerical simulations were also carried out for a rainwater storage tank installed under ground for domestic application of the heat pump with different operating modes, heating loads and the sizes and types of heat exchanger. 相似文献
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K. Nithyanandam R. Pitchumani 《International Journal of Heat and Mass Transfer》2011,54(21-22):4596-4610
Latent thermal energy storage system (LTES) is an integral part of concentrating solar power (CSP) plants for storing sun’s energy during its intermittent diurnal availability in the form of latent heat of a phase change material (PCM). The advantages of an LTES include its isothermal operation and high energy storage density, while the low thermal conductivity of the PCM used in LTES poses a significant disadvantage due to the reduction in the rate at which the PCM can be melted (charging) or solidified (discharging). The present study considers an approach to reducing the thermal resistance of LTES through embedding heat pipes to augment the energy transfer from the heat transfer fluid (HTF) to the PCM. Using a thermal resistance network model of a shell and tube LTES with embedded heat pipes, detailed parametric studies are carried out to assess the influence of the heat pipe and the LTES geometric and operational parameters on the performance of the system during charging and discharging. The physical model is coupled with a numerical optimization method to identify the design and operating parameters of the heat pipe embedded LTES system that maximizes energy transferred, energy transfer rate and effectiveness. 相似文献
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孔隙率与含水率对砂质土样导热系数的影响 总被引:3,自引:0,他引:3
鉴于研究岩土体导热系数的变化规律及影响因素,对岩土的导热理论和工程实践的现实意义,利用热探针测定了不同孔隙率和含水率条件下的砂质土样导热系数,分析其变化规律,并用1stOpt软件得到孔隙率、含水率与导热系数的拟合公式。计算结果与试验结果表明,导热系数随孔隙率的增加而减小,随含水率的增加而增大,且在一定含水率下,导热系数随孔隙率的增加呈线性减小,孔隙率为0.468~0.511时,导热系数降幅为20.19%;在一定孔隙率下,导热系数随含水率的增加呈非线性增长,含水率0~10%时,导热系数增幅为338.38%,含水率10%~15%时,导热系数的增幅为8.83%。 相似文献
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Embedded copper tube sand mold casting is the main manufacturing method of iron‐making blast furnace copper cooling stave, comparing embedded copper tube outer wall temperature with copper melting point is used to judge the fusion between liquid copper and embedded copper tube. On the basis that the computational model is reliable though experimental proof, the paper studies the influence of cooling medium characteristics on the embedded copper tube outer wall temperature. The calculated results show that the cooling medium thermal physical properties play a vital role on heat transfer between the liquid and embedded copper tube in the process of casting and determine the embedded copper tube outer wall temperature and the fusion. Through the numerical research, the cooling medium with suitable physical properties is found, adjusting the cooling media Reynolds number is an effective way to regulate the embedded tube outer wall temperature to the temperature required for fusion; in addition, modifying the cooling medium temperature entering the embedded tube is also a means adjusting the embedded tube outer wall temperature and improving the fusion between the embedded tube and liquid copper, but the method is not easy to operate in practice. 相似文献