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非稳态过程导热系数测定及仪器研制 总被引：1，自引：0，他引：1
基于傅里叶导热基本定律,采用固定热面温度、测定非稳态过程冷面温度及积分法测定传导热量的方法,建立导热系数的简单测定方法.对冷面温度和测得的导热系数进行回归分析得到0℃时的导热系数及温度系数.此方法及基于此方法研制的仪器用于导热系数测定,测定结果与资料的给定值一致. 相似文献
2.
石玉冰 《濮阳职业技术学院学报》2010,23(4):147-149
本文根据对非电解质水溶液导热系数影响因素的分析,导出了估算非电解质水溶液导热系数的计算模型。利用该模型计算了14个体系446个数据点不同温度和组成的二元水溶液的导热系数,计算值与实验值的总平均相对偏差为1.273%,与实验数据吻合很好,计算准确性在相当大程度上优于文献方法。本文方法简单方便,只需要水溶液各组分的临界温度、临界体积和导热系数数据,就可以直接预测各种温度和组成的非电解质水溶液的导热系数。 相似文献
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基于逐层传热计算方法,计算高真空多层绝热传热量,进而确定高真空多层绝热综合导热系数.结果表明,外界环境温度越高,升高相同温度,高真空多层绝热传热量增加越多,综合导热系数增加越多;基于综合导热系数,进行高真空多层绝热温度场数值模拟研究.结果表明,越靠近冷端,绝热层中温度变化越大,温度降低越明显;越靠近热端,绝热层中温度变化越小,温度升高越微弱. 相似文献
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《南阳师范学院学报》2017,(9):28-32
南阳盆地处于中国南北气候过渡带和东西地理交会处,研究南阳盆地的土壤呼吸温度敏感性对探究中国陆地生态系统碳循环过程的气候变化的响应和适应有重要意义.土壤呼吸温度敏感系数Q10值是模拟全球变暖与生态系统碳释放之间反馈强度的重要参数,利用ACE自动土壤呼吸测量仪对南阳市郊的农田裸地进行土壤呼吸探测,对研究地的土壤呼吸变化的温度敏感性进行评析.结果表明研究地的土壤呼吸随土壤表层温度上升呈上升趋势,通过分析得出研究地土壤呼吸温度敏感系数Q_(10)为1.75.土壤表层温度、土壤相对湿度在不同程度上影响着土壤呼吸变化,其中土壤表层温度的影响最为显著(R2=0.4858). 相似文献
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研制了一种基于FD-TC-B型导热系数测量仪的加热平台.采用DS18B20集成温度传感器对温度信号采集,由AVR单片机结合上位机编辑LabVIEW软件功能模块进行数据处理,通过PID算法稳定控制加热盘温度,实现全自动数据采集和处理,实时显示温度曲线,数据自动存储和计算,良好人机界面功能的改进型导热系数测量仪.介绍了系统硬件和软件设计,并通过测量验证了改进型导热系数测量仪装置可靠,数据直观准确、精度高、测量时间短和测量方法简单,能满足科研测试和教学实验的要求. 相似文献
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吉世Yu 《昆明师范高等专科学校学报》2001,23(4):77-78
通过对温度从300K到2500K范围内，作为热发射体常用基底金属W的导热系数的实验结果进行分析，得到了W的导热系数随温度变化的经验公式，为W作为基底的发射材料的热学研究提供了依据。 相似文献
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《南阳师范学院学报》2020,(4):9-15
为探明南阳盆地降水对土壤呼吸的影响,利用ACE自动土壤呼吸测量仪对南阳市郊区人工林地进行土壤呼吸速率及环境因子探测.结果表明:①土壤水分对土壤呼吸有促进作用,同时会降低土壤呼吸的温度敏感性,在20～30℃和24～34℃温度区间,雨后Q_(10)值均小于雨前.②在正常情况下,通过单因子回归分析,发现土壤呼吸速率与土壤温度和土壤体积含水量的相关性都处于低度水平,土壤呼吸速率与土壤温度拟合的相关性优于土壤呼吸速率和土壤体积含水量的相关性,采用决定系数最优法筛选单因子拟合方程,发现幂函数模型效果最好(R2=0.272).③土壤体积含水量的提高会降低土壤呼吸速率与土壤温度的相关性,由0.371(p≤0.01)下降至0.345(p≤0.01),控制土壤体积含水量,计算出土壤呼吸速率与土壤温度之间存在低度正相关关系,偏相关系数为0.297～0.383(p<0.01),且偏相关系数小于未加控制的相关系数. 相似文献
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沥青混合料作为一种感温性材料,其组成材料的导热系数关系到路面温度场的变化及路面性能.采用XIATECH TC3000型导热系数仪测试四种岩性集料、四种沥青和四种级配类型下的沥青混合料导热系数,并基于灰关联性和分形维数计算混合料组成特性和环境因素与导热系数的灰关联度.研究发现,水分、短期老化和温度环境因素对沥青混合料的导... 相似文献
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在共晶盐BaCl2水溶液中添加亲水性分散剂,经过超声振动制备了粒径为20nm的4种不同体积分数的TiO2-BaCl2-H2O纳米流体。运用瞬态热线法对其进行导热系数的量测。实验表明,加入纳米粒子后可显著提高其导热系数。本文同时分析了温度及粒子体积份数对导热系数的影响。 相似文献
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At present ,during the design of ground source heatpump (GSHP) systems ,technical attention is always fo-cused on vertical borehole heat exchangers and surroundingsoil[1 ,2],butthe effects of their shallowhorizontal connect-ing pipes ,or horizontal ground… 相似文献
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李薇 《兰州石化职业技术学院学报》2005,5(3):9-10
通过对化工管道设备热损失的计算分析,推出结论:并非在任何情况下保温材料的厚度越大,保温效果越好;用两层保温材料保温时,导热系数小的材料包在内层,热损失小,保温效果好. 相似文献
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INTRODUCTION It is recognized that the transfer of soil moistureand heat occur simultaneously and are interrelated.Since the 1950s, many models have been developed,based on two nonisothermal water-heat coupledmodels by Philip and de Vries (1957) and Taylor andLary (1964), respectively. In China, some researcheson modeling coupled transfer of soil moisture andheat have also been conducted on the arid soils innorthern China (Kang et al., 1993; Guo and Li, 1997;Hu et al., 1992; … 相似文献
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Simulation models of heat and water transport have not been rigorously tested for the red soils of southern China.Based on the theory of nonisothermal water-heat coupled transfer, a simulation model, programmed in Visual Basic 6.0, was developed to predict the coupled transfer of water and heat in hilly red soil. A series of soil column experiments for soil water and heat transfer, including soil columns with closed and evaporating top ends, were used to test the simulation model. Results showed that in the closed columns, the temporal and spatial distribution of moisture and heat could be very well predicted by the model,while in the evaporating columns, the simulated soil water contents were somewhat different from the observed ones. In the heat flow equation by Taylor and Lary (1964), the effect of soil water evaporation on the heat flow is not involved, which may be the main reason for the differences between simulated and observed results. The predicted temperatures were not in agreement with the observed one with thermal conductivities calculated by de Vries and Wierenga equations, so that it is suggested that Kh, soil heat conductivity, be multiplied by 8.0 for the first 6.5 h and by 1.2 later on. Sensitivity analysis of soil water and heat coefficients showed that the saturated hydraulic conductivity, Ks, and the water diffusivity, D(θ), had great effects on soil water transport; the variation of soil porosity led to the difference of soil thermal properties, and accordingly changed temperature redistribution,which would affect water redistribution. 相似文献
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Based on the surface energy balance model which is widely used abroad, a temperature and humidity field coupling model of conservatory soil without crop vegetation in full illumination was established. Considering the relatively closed environment in conservatory, weak solar radiation and little surface evaporation of soil, the daily variation of water content in different soil layers may be neglected, then the temperature and humidity field coupling model was simplified to a one-dimensional thermal diffusion model. The simplified model and the temperature and humidity field coupling model adopted the same computational method of soil physical parameters and discrete format of heat diffusion differential equations, and were applied to the continuous simulation of temperature field in conservatory soil without crop vegetation in full illumination. Through the comparison between simulation results and experimental data, the precision of the simplified model was verified. The typical rule of soil heat flux variation in a 24 h cycle was also obtained. 相似文献
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宋君萍 《实验室研究与探索》2010,29(4)
使用激光导热仪测试4种炭黑以不同体积分数填充天然橡胶复合材料的导热性能。介绍了激光导热仪的测试原理、测试前的准备工作、测试过程以及测试工作的注意事项等,给出热扩散系数、比热与导热系数随温度的变化规律和不同炭黑的导热性能对比情况,并进行合理性分析。结果表明,采用激光导热仪测试橡胶导热性能是可行的,采用的方法是可靠的。 相似文献
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Thermal conductivity of soils with heavy metals concentration from the Niger Delta region of Nigeria
Akinyemi OD Olowofela JA Akinlade OO Akande OO 《Journal of Zhejiang University. Science. B》2006,7(8):615-618
INTRODUCTION Knowledge of soil thermal properties is an im- portant factor in understanding mass and energy ex- change processes in the soil-atmosphere system. The chemical composition of the soils will therefore in- directly relate to their thermal conductivities. Ac- cording to Usowicz (1993), this knowledge can also help in controlling the thermal-moisture regime of soils. Soil properties often correlated with metal ad- sorption include soil pH (Christensen, 1984; Harter, 1983), soil … 相似文献
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闫锡杰 《通化师范学院学报》2002,23(5):60-63
传统的稳态法测量不良导体的导热系数是用红外线灯泡当作热源，用热辐射的方式对被测样品进行加热，新改进的加热方式是用电熨斗当热源，采用接触的方式进行加热。实践证明：新改进的加热方式具有实验操作简单，测量的结果误差小，节省电能，降低成本等特点。 相似文献
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以Alaska北极美国Barrow气象观测站的地温观测资料和土壤热物理参数为基础。以伴有相变问题的一雏热传导方程的有限差分法为工具。在考虑和忽略未冻水2种情形下模拟了Barrow地区0.29,0.50和1．0m深处的地温值，并与观测值进行了比较,计算结果表明，未冻水对冻土热状况数值模拟结果有很大影响． 相似文献
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Measurement of the thermal transport properties of dielectric thin films using the micro-Raman method 总被引：1，自引：0，他引：1
The micro-Raman method is a non-contact and non-destructive method for thermal conductivity measurement. To reduce the measurement error induced by the poor fit of the basic equation of the original micro-Raman method, we developed a new basic equation for the heat source ofa Gaussian laser beam. Based on the new basic equation, an analytical heat transfer model has been built to extend the original micro-Raman method to thin films with submicrometer- or nanometer-scale thickness. Experiments were performed to measure the thermal conductivity of dielectric thin films with submicrometer- or nanometer-scale thickness. The thermal resistance of the interface between dielectric thin films and their silicon substrate was also obtained. The obtained thermal conductivity of silicon dioxide film is 1.23 W/（m.K）, and the interface thermal resistance between silicon dioxide film and substrate is 2.35×10^-8 m^2.K/W. The thermal conductivity and interface thermal resistance of silicon nitride film are 1.07 W/（m.K） and 3.69×10^-8 m^2.K/W, respectively. The experimental results are consistent with reported data. 相似文献