基于线热源模型结合参数估计计算岩土热物性方法探讨

介绍了地源热泵空调系统中基于线热源模型结合参数估计法下的4种岩土热物性计算方法,结合工程实例对比分析了这4种方法的计算结果。建议在实际工程中采用三参数估计法来计算岩土导热系数、钻孔内热阻和岩土容积比热容为妥。     

地源热泵岩土热响应现场测试及分析

介绍地源热泵的岩土热响应现场测试的测试方法和计算模型等。现场测试采用恒热流测试法,并以线热源模型为基础,结合工程最优化方法,采用复形调优法,从而得出所需要的热物性参数、周围岩土综合导热系数和综合比热容,利用实例验证该方法的准确性。     

岩土热响应测试及应用中的问题探讨

岩土热物性参数是地源热泵系统设计的重要基础依据,其准确程度决定着地源热泵系统运行的可靠性和经济性。本文介绍了岩土热物性测试设备构成及数据处理模型,并对热响应测试的某些问题进行了讨论。热响应测试是地源热泵工程应用的基础工作,具有重要意义。目前仍需要对其计算模型、测试方法及装置进行研究。     

地源热泵岩土热响应测试影响因素分析

建立了地源热泵岩土热物性现场测试系统的三维数值模型,基于所建数值模型分析了测试时间、舍弃初始小时数、钻孔半径、岩土体初始温度、加热器输入功率等因素对岩土热响应测试结果的影响。研究结果表明:对于柱热源模型,随着钻孔尺寸的增大,辨识得到的热导率越小;采用参数估计法作为辨识方法时,岩土初始温度的测试精度对辨识结果有较大影响。测试得到的热导率有6%~18%的偏差。     

地源热泵岩土导热系数测试影响因素分析

建立了地源热泵岩土导热系数现场测试系统的三维数值模型,基于所建数值模型分析了测试时间、舍弃初始小时数、钻孔半径、岩土体初始温度、加热器输入功率等因素对岩土导热系数测试结果的影响。研究结果表明:热响应测试时间应大于70h;对于柱热源模型,随着钻孔尺寸的增大,辨识得到的导热系数逐渐减小;岩土初始温度对岩土导热系数辨识结果没有影响,但采用参数估计法作为辨识方法时,岩土初始温度的测试精度对辨识结果有较大影响;对于纯导热模型,加热器输入功率对岩土导热系数辨识结果没有影响。     

两种地源热泵竖埋U型换热器计算模型适用性比较

地下换热器传热模型是地源热泵系统长期运行性能预测以及岩土热物性参数测试的基础。本文通过对经典的线热源解析模型以及一维柱热源数值模型进行比较,整体上数值模型及解析模型的计算平均水温与实测值接近,并且数值模型偏差比解析模型小。数值模型具有较高准确性,并且可以进行变热流计算,具有较强的工程实用价值。     

基于点热源模型的地下岩土热物性参数测试

目前现场热物性测试广泛采用热响应试验方法测得岩土综合热物性参数,而获取各层岩土热物性参数值可以减少地源热泵系统地埋管的设计偏差,满足工程需要。本文提出基于点热源模型进行各层岩土热物性参数测试的方法,并通过模拟验证的方式可以准确得到热物性参数值,可靠性较高,但点热源模型测试方法应用于实际工程是否准确可靠尚须进一步验证。     

岩土热响应试验在土壤源热泵系统设计中的应用

结合南京某土壤源热泵项目,分析了岩土热响应试验中的关键问题,对岩土热响应测试的方法与步骤进行了规范的阐述.针对某一实际项目建立了100m深双U型垂直埋管试验井测试装置进行热响应试验,并采集了岩土热物性参数,得到了土壤原始地温以及地埋管系统的供回水温度响应曲线,进而确定了每延米井深的换热量等参数.数据分析表明,土壤的原始地温为17.95℃,夏季工况(35℃)和冬季工况(5℃),每延米井深的换热量分别为69.6W/m和51.2W/m.该工程区域内综合地质条件比较适宜采用土壤源热泵空调系统.     

对岩土热响应试验的几点思考

岩土热响应试验的目的是确定岩土热物性参数。本文提出一种获得更为准确的岩土热物性参数及钻孔内热阻的方法,介绍如何利用岩土热响应试验数据来推导不同工况下（不同埋管形式、加热功率等）地埋管换热器的运行情况,以期为工程设计提供更多翔实的参考数据。     

地源热泵系统的热响应实验方法研究

土壤的平均导热系数与热阻是影响地下埋管换热器传热性能及地源热泵系统节能性与经济性的重要因素。利用线热源理论,通过地源热泵的工作试验过程,得到系统进出口水温等参数,并通过最小二乘法对所得数据进行拟合,得到地埋管换热器钻孔的导热系数及土壤热物性参数,测试结论对于指导土壤热交换器设计与施工具有一定的参考价值。     

岩土热物性测试若干问题探讨

针对目前在地源热泵岩土热物性测试领域存在的不规范现象,在研究与实践基础上,对测试参数、数据处理、功率、单位延米换热量的获得方法、测试工况等问题进行讨论,并提出相关建议。     

岩土热响应测试仪的开发与应用

开发一套岩土热响应测试仪,介绍其原理与组成,以及配套开发的控制软件、数据采集软件、数据处理软件的功能和使用方法。使用所开发的仪器进行现场实测,测试结果表明,该设备及配套软件完全达到预期性能指标,能够在今后对外开展岩土热响应试验的工作。     

热响应试验过程及相关参数探讨

为使相关测试人员更好地了解热响应试验,获得准确的岩土体热物性参数,结合笔者长期的试验经验对热响应试验原理、试验过程、试验相关参数及各参数的影响因素等内容进行全面阐述,对单位换热量和钻孔热阻进行深入分析.     

Finite element analysis of the localised thermal quench of an HTS tape

In this work, we perform a finite element method (FEM) analysis of the localised thermal quench of a high temperature superconducting (HTS) tape. One 3D thermo-electric coupling FEM model, which is constructed to address the actual development of the localised thermal quench occurred in the HTS tape, has been proposed. One quench experiment is performed to validate this model. It is shown that the mode can quantitatively reflect the dynamic and static quench characteristics when comparing the results of the experiment with the model. The FEM model generates an estimate of the location of the highest temperature and visualisation of the quench dynamics.     

钛合金锥形件温热剪旋热力耦合有限元模拟

成形过程中的温度场变化对钛合金锥形件温热剪旋成功与否,以及产品的精度影响很大.在数值模拟时叠加符合实际的热源边界条件显得非常重要.针对TC4钛合金锥形件建立了三维热力耦合有限元模型,在有限元模拟过程中叠加了火焰加热边界条件.计算了成形过程中工件和芯轴上温度场的分布情况.所建立的有限元模型更加符合实际工况,模拟结果更加真实可靠.     

人工神经网络在玻璃配方设计中的应用研究

应用人工神经网络技术,采用Neuralworks Predict软件建立BP网络模型,通过对R2O-MO-Al2O3-SiO2系统玻璃组成与热膨胀系数关系实验数据的训练,以期能预测该系统指定组成的玻璃的热膨胀系数?研究结果表明,所建立的神经网络模型能较正确地反映玻璃氧化物组成与其热膨胀系数之间的规律性。模型对给定组成玻璃热膨胀系数的预测值与实际测试值的相对误差在6．4％以内,表明由神经网络技术建立的这一模型能正确反映R2O-MO-Al2O3-SiO2系统玻璃组成与热膨胀系数间的内在规律性。     

Features of calculating the descent velocity of the lower boundary of the near-ceiling layer in a fire in an atrium

Results of calculating the dynamics of descent of the lower boundary of the near-ceiling gas layer in a model atrium using various zone approaches and a field model are presented. Comparison with experimental data is made. It is shown that when a zone mathematical model is used it is necessary to take account of the shape of the convective column formed above the source of combustion. It is pointed out that the application of the approximation of an unrestricted buoyant plume to describing parameters of the convective column does not reflect the actual thermodynamic picture of the fire development (primarily the effect of the atrium ceiling) and can lead to both an understatement and an overstatement of the fire danger of atria.     

Crown Sensitivity of the Magnetic Recording Head Gimbal Assembly Bonded by a Viscoelastic Adhesive

The temperature excursions inside a magnetic recording disk drive can be as much as 20 to 60°C. When subjected to these temperature changes, thermal expansion coefficient mismatch between the ceramic slider and the stainless steel suspension causes bending. This thermal bending is mediated by the viscoelastic properties of the polymeric adhesive attaching the slider and the suspension. We employ the elastic-viscoelastic correspondence principle to model thermal bending. We calculate thermal bending up to 30 nm for a high-modulus adhesive and only 0.8 nm for a low-modulus adhesive over typical temperature variations. The low-modulus adhesive exhibited remarkable time-dependent oscillations during a successive ramp-and-hold temperature profile. These oscillations are expected to be a general phenomenon that should be observed under similar conditions of length, time, temperature, and mechanical properties of the bonded beams and adhesive. The calculated rate of temperature-dependent thermal bending was in good agreement with that measured on actual magnetic recording head gimbal assemblies. This is the first analysis that employs a viscoelastic adhesive model and the correspondence principle to describe slider crown phenomenon.     

导热高分子材料在包装印刷领域的研究进展

目的综述导热高分子材料在包装印刷领域的应用及研究现状,拓展导热高分子材料的应用领域。方法首先介绍2类导热高分子材料的制备方法,即本征型和填充型导热高分子材料;其次全面综述用于包装印刷领域的导热膜/纸、导热胶黏剂和导热油墨;最后总结常用的各类导热机理模型。结果与本征型导热高分子相比,填充型导热高分子具有加工简单、成本低廉、应用面广等优点,是目前研究最多的导热高分子材料。导热膜/纸、导热胶黏剂和导热油墨具有广泛的研究基础,市场需求旺盛。导热预测模型虽能够有效预测复合材料的热导率,但会受到填料含量和粒子形貌的影响。结论导热高分子材料在包装印刷领域拥有巨大的应用需求,开展导热高分子的研究具有重要的现实和理论意义。     

Illusion Thermotics

“Fata Morgana” or “Mirage” phenomena have long been captivated as optical illusions, which actually relies on gradient‐density air or vapor. Man‐made optical illusions have witnessed significant progress by resorting to artificially structured metamaterials. Nevertheless, two long‐standing challenges remain formidable: first, exotic parameters (negative or less than unity) become inevitable; second, the signature of original object is altered to that of a virtual counterpart. It is thus not able to address the holy grail of illusion per se, since a single virtual object still exposes the location. In this study, those problems are successfully addressed in a particular setup—illusion thermotics, which identically mimics the exterior thermal behavior of an equivalent reference and splits the interior original heat source into many virtual signatures. A general paradigm to design thermal illusion metadevices is proposed to manipulate thermal conduction, and empower robust simultaneous functions of moving, shaping, rotating, and splitting heat sources of arbitrary cross sections. The temperature profile inside the thermal metadevice can mislead the awareness of the real location, shape, size, and number of the actual heat sources. The present concept may trigger unprecedented development in other physical fields to realize multiple functionalized illusions in optics, electromagnetics, etc.