多功能低温实验箱的改进与应用

针对食品冻结与储藏保鲜要求恒温、恒湿、空气流速和电子膨胀阀特性等研究工作,在原有低温箱的基础上进行了改进,使其具有模拟低温环境的功能.本文重点研究恒温恒湿、电磁阀的控制方式以及介绍一系列相关实验的结果.     

恒温恒湿空调系统的优化控制与性能模拟

针对传统恒温恒湿空调系统表冷器采用固定露点方法导致热湿补偿损失较大的缺点,采用热湿独立控制装置和PID分程控制方法,研制了一套恒温恒湿空调系统。在实验的基础上,利用TRNSYS 16软件建模,对系统在不同热湿负荷下的运行状况及节能效果进行了模拟分析。结果表明,该系统能自动调节表冷器冷冻水流量与温度,以及加热器或加湿器的投入量,实现对空气温湿度的独立控制,并达到设定的温湿度;在设计此类表冷器时,换热面积应该以较高的冷冻水进口温度(如12℃而不是通常的7℃)来进行计算。该系统节能效果显著,比传统系统在低温高湿工况下节能30%以上;在高温低湿工况下节能50%左右。     

恒温恒湿空调房间的解耦控制方案

采用机制分析和实验分析相结合的方法，建立恒温恒湿空调系统的数学模型，推导四输入、四输出的传递函数矩阵，采用前馈补偿法设计解耦补偿器，使恒温恒湿空调系统的传递函数矩阵变换为对角矩阵，从而解除各个控制回路之间的耦合，并通过仿真进行验证。结果表明，该解耦控制器在恒温恒湿空调系统中的应用效果较好，改善和提高系统的品质和性能。     

高精度恒温恒湿空调的研发及试验验证

叙述普通恒温恒湿机组存在的弊端，阐述提高恒温恒湿机组精度的几种常用方法，着重论证通过粗调回风温湿度和微调送风温湿度的控制方法的简单性、经济性和可行性。     

高精度恒温恒湿空调最佳控制方法研究

针对不同制冷系统配置及控制方法,对恒温恒湿空调系统进行对比试验,结果表明,采用容量可调的数码涡旋式压缩机和电热式加湿器,以及4通道独立PID等的控制方法可以大幅提高恒温恒湿空调的控制精度。     

低湿度恒温恒湿环境的实现方法

通过对一种新型恒温恒湿空调器的设计、安装及调试介绍，说明实现低湿度恒温恒湿环境的方法。该恒温恒湿空调器适用于电子、电池生产等行业低湿度、高精度恒温恒湿要求的场合。     

关于恒温恒湿空调器问题的探讨

本文从恒温恒湿空调器的工作原理、机组设计选型、施工及调试运行等方面进行介绍分析,指出采用恒温恒湿空调器的系统存在的常见问题,并提出一些处理建议供参考.     

档案馆母片库低温低湿环境的实现

通过一种空气处理的方法,实现档案馆母片库的低温恒温恒湿要求。     

马铃薯种子贮藏环境的温湿度智能控制应用

马铃薯种子贮存需要一个恒温恒湿的环境，本文对马铃薯种子贮藏环境温、湿度的微机测控系统进行研究，并应用到实际工程当中，取得了很好的效果，提高了贮存质量。     

恒温恒湿空调系统全年运行控制

结合焓湿图分析了空调系统全年恒温恒湿空气处理过程,分别给出了小型和中大型精密恒温恒湿空调系统的控制系统图．并介绍了相应的全年运行控制方法。     

Scanning iron temperature lidar for mesopause temperature observation

We introduce a new method for temperature profile measurements in the mesopause region in the altitude range from 80 to 105 km. A frequency-doubled narrowband alexandrite laser is used to scan the iron resonance line at 386 nm. The isotopic shifts of the iron isotopes and the laser bandwidth are derived by the measurement itself. Neglecting the minor isotopes results in large temperature errors up to 28 K. We discuss the derived temperatures in comparison with results of our potassium temperature lidar. The iron lidar-derived temperatures have typically a statistical error of 0.4 K and vary by less than 10 K, which is due to the daily natural variation. The all-solid-state system, which is compact, can be containerized and deployed at remote locations.     

Dynamic temperature model and dynamic temperature compensation ofcrystal oscillators

In temperature-compensated crystal oscillators (TCXO), the compensating action is commonly estimated as a function of one variable-environmental temperature, At the same time, experimental data show that TCXO frequency stability is also dependent on the dynamics of the temperature process. The greater the temperature variation, the more pronounced Is the loss of temperature compensation. In this paper, the origins of this phenomenon are analyzed, and a method for reducing its effects is presented. A new approach is suggested according to which the compensating action is formed as a function of two variables: the temperature and the rate of its variation. A theoretical basis for this method is given. A functional model of the devices performing the dynamic temperature compensation is suggested. Experimental investigations of a TCXO with a microprocessor-based dynamic temperature compensation system confirmed the possibility of TCXO frequency stability improvement in nonstationary thermal conditions. In a system using an AT cut resonator and a separate Y-cut thermosensor, the application of dynamic temperature compensation resulted in an order of magnitude improvement as compared to conventional digital temperature compensation procedures. Even with dual-mode SC-cut resonators, the application of dynamic temperature compensation is shown to be useful     

Assessment of failure temperature of ultra-high temperature ceramic plates

A theoretical model is presented to assess the failure temperature for ultra-high temperature ceramics (UHTCs). The parameters in the present work, such as thermal expansion coefficient and Young’s modulus, are considered functions of temperature to calculate the stress field of UHTCs under high temperature conditions. The critical elevated temperature for failure is calculated by using the Maximum Principle Strength theory. By establishing the relation between the temperature and the mechanical properties of the UHTCs, it is found that the failure behavior of UHTCs is affected by initial temperature.     

Assessment of failure temperature of ultra-high temperature ceramic plates

A theoretical model is presented to assess the failure temperature for ultra-high temperature ceramics (UHTCs). The parameters in the present work, such as thermal expansion coefficient and Young’s modulus, are considered functions of temperature to calculate the stress field of UHTCs under high temperature conditions. The critical elevated temperature for failure is calculated by using the Maximum Principle Strength theory. By establishing the relation between the temperature and the mechanical properties of the UHTCs, it is found that the failure behavior of UHTCs is affected by initial temperature.     

液氦温区国际温标的转换

概括介绍液氦温区国际实用温标的发展情况,系统地给出温标T24,T29,T32,T37,TBS,T48,T55E,TL55,T58,T62,T68,T76以及目前正在采用的T90之间的转换关系,为此编写了计算机程序,可直接用于以上各温标间的数值转换.     

Real-time temperature calculation and temperature prediction of wet multi-plate clutches

Forschung im Ingenieurwesen - Many applications of wet multi-plate clutches are within safety-critical areas since malfunction or failure of the clutch is often equivalent to “loss of...     

Relationship between crystallization temperature and melting temperature in crystalline materials

The ratio of the absolute temperature at which the homogeneous nucleation rate or the crystal growth rate is maximum (T _cmax) to the absolute melting temperature (T _m) is analysed by two parameters: one is the ratio of the activation energy for migration (E) and the heat of fusion (H _m), the other is the ratio of mean molar surface energy and H _m. In analysing the crystallization data for a large number of crystalline materials such as metals and inorganic, organic and polymeric materials, the ratios and E/H _m show roughly constant values for a given type of material. The constancy of the two parameters will then give rise to a constant value ofT _cmax/T _m.     

超高温传感器用感温材料与结构特性分析

针对现有蓝宝石光纤温度传感器测温上限难以突破1 700℃的瓶颈问题,本文分别从传感器测温结构和感温材料两方面进行了分析改进,以满足对2 000~2 500℃超高温的测量需求.提出了一种接触-非接触相结合的新型传感器测温结构,并结合非接触式测温结构特点给出了Plank黑体辐射温度误差补偿公式,解决了非接触结构的准确测温问题.结合不同感温材料特性分别对难熔金属、陶瓷基复合材料和C/C复合材料的高温性能进行分析比较,包括材料强度、密度、抗氧化性、塑性、熔点等,筛选出适合作为超高温传感器的备选感温材料.针对筛选出的感温材料设计了抗热震性试验和抗氧化烧蚀试验,实验结果表明Hf B2-Si C复合材料能够满足超高温环境下对感温材料物理特性的特殊需求.传感器温度试验结果表明,采用接触-非接触式新结构和Hf B2-Si C感温材料的新型光纤温度传感器可对2 500℃高温进行长时间稳定测量,测量精度达到±1%.     

Spatial distribution of temperature and temperature instability of a thermoelement

We show that, depending on the spatial distribution of temperature in semiconducting thermoelements, both "negative" (onset of temperature instability at negative temperature differences) and "positive" temperature instabilities may set in. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 3, pp. 542–543, May–June, 1998.     

盲孔测温传感器瞬态温度测试研究

目前炮膛内壁瞬态温度具有温度高、变化快、测试环境恶劣等特点,不便于准确测量,普遍采用动态校准方法来减少瞬态温度的误差,但是该方法对仪器动态性能要求高。该文根据测试系统原理,利用盲孔测温传感器验证炮膛内壁瞬态温度的变化,采用非接触式测量瞬态温度,同时利用分析法外推技术对0.05 cm和0.1 cm处的温度进行推导。实验表明:在误差允许的范围内,0.05 cm和0.1 cm处的温度与实验测得的温度变化一致。论证该系统对炮膛内壁瞬态温度测量的可行性,可以完成在恶劣环境下的数据测量,并且该系统成本低,数据可靠,结构简单,对今后更加深入地研究膛内壁瞬态温度有参考价值。