共查询到20条相似文献,搜索用时 62 毫秒
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研制了一种智能非接触全热流计,该热流计由辐射检测器和单片微型计算机信号采集与处理系统组成。用它不仅可以在线测量表面的全热流,而且还可同时测出被测表面的真实温度和发射率。当被测表面温度范围为100~450℃、发射率不低于0.5时,全热流的相对测量误差小于4.0%。 相似文献
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在对热流计自身性能校准时,被校热流计是用双面胶纸粘在主加热器上,因而造成在热流计粘上和撕下的多次操作中很容易损坏加热器。为此,作者对校准时热流计的安装方法进行了改进,改粘贴方法为对准方法,实验表明,采用对准方法后的偏差不超过0.85%,而且对主加热器没有任何损伤,大大地提高了其使用寿命与可靠性。 相似文献
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研究了风速对电容武湿度传感器最终测量值和响应时间的影响,并分析了产生影响的机理;根据测量数据拟合出了电容武湿度传感器的响应时间和风速之间的函数关系. 相似文献
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在全面分析煤油燃气辐射特性的基础上,结合煤油燃气的具体特点,提出了适合于测量煤油燃气温度的辐射测量方法[4],并且建立了辐射测温系统,通过对煤油燃气温度的实际测量,验证了辐射测温法测量燃气温度的可行性。 相似文献
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利用复数矢量法和图论的理论对胶印机榆墨系统响应时间进行建模,构建了胶印机输墨系统响应时间的教学模型.根据这一新的模型可以计算任意的给定参数的胶印机输墨系统响应时间,为胶印机输墨系统的设计者提供理论依据,具有一定的理论和实际应用价值. 相似文献
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Yu. I. Azima 《Measurement Techniques》2006,49(12):1224-1232
A method of measuring unsteady heat flow, based on the balance equation of heat flows at the entrance and inside the object,
is described. The theoretical principles for obtaining formulas and results of investigations on a thermal model are presented.
Diagrams of a heat meter and of a measuring system are given.
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Translated from Izmeritel’naya Tekhnika, No. 12, pp. 37–41, December, 2006. 相似文献
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露点是低温风洞运行的关键参数,为解决低温风洞极低露点(–100℃)测量中存在的响应速度低、量程小和精度不高的问题,在–80℃露点测量装置研究基础上,通过优化专用斯特林制冷系统性能,大幅缩短降温时间;采用具有内狭缝换热器的一体化镜面,提高镜面结露的均匀性,使得反射光强度阶跃特征点更清晰;测量光路上加装球面镜头,提高–100℃露点温区结露时光电信号的强度,保证测量的可靠性;采用基于周期法露点测量方法,避免镜面结露的平衡振荡过程,缩短露点检测周期,提高露点测试响应时间。测试结果表明,在–100℃露点温区时,实现±1℃的露点测量精度,从–90℃到–100℃露点温区的露点测试响应时间仅为12 min,可以满足低温风洞极低露点测试的需求。 相似文献
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Raj PK 《Journal of hazardous materials》2008,159(1):61-71
The NFPA 59A Standard and the Federal Regulation, 49 CFR Part 193, stipulate a level of 5 kW/m(2) as the criterion for determining the hazard distance to people exposure from a LNG fire. Another regulation (24CFR, Section 51.204) while stipulating a lower exposure limit of 1.42 kW/m(2) provides administrative relief from the regulation if mitigation measures are provided. Several countries in Europe and the Far East have adopted both a specified heat flux value (generally, 5 kW/m(2)) as well as modified dose criteria for human exposure hazard calculation in risk assessments. In some cases, the regulations in Europe require the use of lower values for children and physically challenged persons. This paper reviews the available literature on the phenomenon of skin burn caused by radiant heat exposure. The associated thermal and spectral properties of human skin are reviewed. The basis for regulatory setting, of 5 kW/m(2) and other exposure criteria (as a part of hazard and risk calculations) for evaluating distances to hazards from the exposure of people to radiant heat effects of large fires, is evaluated. An example calculation is provided to show the extent of reduction in the hazard distance to specified radiant heat flux from a fire when the spectral reflection and absorption properties of skin are considered with and without the inclusion of the mitigating effects of clothing. The results indicate that hazard distances calculated including the reflective and band absorptive properties (in IR wavelength) of skin results in a reduction of between 30 and 50% in the hazard distances obtained with current methodology, which ignores these effects. Unfortunately, there are no test results, from full-scale human-exposure-to-IR radiation, with which these predictions can be compared. 相似文献
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U型竖埋管地源热泵-辐射地板联合运行冬季启动特性实验研究 总被引:1,自引:0,他引:1
对U型竖埋管地源热泵-辐射地板联合运行实验冬季运行启动特性进行分析,研究启动阶段U型竖埋管进出水温的变化规律,得出平均每米井深的换热量。研究启动阶段辐射地板供暖的进出水温的变化规律,为地源热泵及辐射地板在长江中下游地区的工程设计与应用推广提供参考。 相似文献
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周兴红 《制冷与空调(四川)》2007,21(4):90-93,97
根据地板采暖的特点,建立数学模型,采用有限差分法对地板层内部的非稳态传热过程进行计算,并就地板层内部、地板表面温度场的分布及其影响因素进行分析,并对预热时间进行研究,为地板辐射采暖系统的推广和应用奠定一定的理论基础。 相似文献
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根据热能表的基本原理,选择MSP430系列单片机,采用超声流量计与铂电阻测温相结合的方法设计了公称直径为DN15的低功耗超声热能表.按照国家相关标准对该系统进行了检定.结果表明,该超声热能表符合国家2级表标准,系统的平均工作电流为35μA. 相似文献
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在对冰浆流体的换热情况提出一系列假设前提下,建立等效比热容模型,用于描述冰晶粒子融化吸收潜热。运用有限差分的方法,对所得的差分方程组进行求解,从而得到定热流状态下圆管内层流冰浆流体的传热特性。计算结果表明,随着含冰率的增大和Ste的减小,平均Nu增大,换热性能得到加强。 相似文献
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This paper describes the measurement of the peak and recovery heat flux densities (qP, qR) in a bath of subcooled superfluid helium. A RhFe wire (d = 51 μm, L = 34.8 mm) was horizontally immersed in a He Ilp cryostat, which served as the sample, the heater and the temperature sensor. For the steady state measurement a programmed voltage method with a triangular waveform of 20 s was applied. The measured qP and qR values cover the temperature range 1.81–2.1K at a pressure of 0.1 MPa. On the basis of the heat and mass transfer through phase interfaces, theoretical relations (without geometrical parameters) of qP and qR are derived, which have very wide application range due to the relative critical heat flux density method used for the calculations. The theoretical results fit the experimental results well for both qP and qR. 相似文献
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地埋管换热器实际运行时,热流总是变化的。为了研究变热流模型的正确性,本文讨论变热流下叠加原理在无限长线热源模型中的应用,以及此模型下地埋管换热器进出口水温的理论解。先保证热流恒定,对上海市某别墅地源热泵项目进行现场实测,将测试得到的相关参数作为已知。待岩土温度恢复到初始值时,进行变热流试验,通过变热流模型计算的进出口水温与实测的进出口水温比较,相对误差基本小于2%,最大误差不超过3%。 相似文献