小型恒温箱恒温性能的理论及实验研究

通过分析恒温箱内外的热量平衡，建立箱体内部温度变化的动态方程，进行理论求解，并分析箱体形状系数和内热源对箱体内部温度的影响。同时设计1台有效恒温空间为1350mm×340mm×450mm的小型恒温箱，进行不同温度波动下的恒温特性。结果表明，冷热源方式对恒温箱内温度的稳定有较大影响，较大的体型系统有利于维持恒温，另外动态方程的计算结果与实验相符。     

流通环境对液氮充注蓄冷配送箱保温性能的影响

目的 为了提高液氮充注蓄冷配送箱在流通过程中的保温性能,保证配送品质。方法 搭建配送箱流通环境模拟试验平台,研究不同外界风速、外界温度和振动频率对蓄冷配送箱内空气温度变化和温度场分布的影响。结果 试验结果表明,当外界风速增大时,箱体内部环境的升温速度也会增大;外界温度对液氮充注完毕后箱内最低温度产生较大影响,箱体内部空气最低温度随外界温度降低而降低,同时始终在运输过程中维持较低的温度,箱体内温度场均匀性先提高后降低;振动对箱体内部环境的升温速度影响较大,而随着振动频率增大,箱体内部的温度场均匀性变差。结论 该研究可为蓄冷运输配送设备的设计与优化提供参考。     

低温冻土导热系数测定仪的设计与研制

冻土导热系数的测定对于研究冻土热物理性质、土体冻胀特性有着重要作用。本文将介绍低温冻土导热系数测定仪，包括其低温冷水域系统、制冷系统、温控系统、测温系统及数据采集系统的设计与研制。导热系数测量的关键在于温度的测量与控制，本装置利用比例积分微分（PID）调节原理，通过控制冷水域水箱内的加热管来调节冷液温度，保证其恒温精度要求。温度数据通过数据采集仪采集，并利用算术平均滤波法对结果进行处理。     

碳系水性电热油墨在外卖恒温箱中的应用

目的 改善外卖箱的保温性能，解决低温条件下热餐食物在配送过程中热量大幅度流失的问题。方法 应用发热性能良好且环保的碳系水性电热油墨，结合丝网印刷技术制备发热器件并装配在发泡聚丙烯(EPP)外卖箱中，从而维持箱内恒温。结果 所制备的发热器件在18 V电压条件下饱和温度可达到76.7 ℃，温度和功率密度呈线性关系，斜率高达782.6 ℃.cm²/W。在使用了发热器件之后，恒温箱内温度可长时间保持在60 ℃以上。在从环境温度开始加热的恒温箱中经过1 h的配送过程模拟实验，初始温度约为60 ℃热餐食物温度下降仅有5 ℃。在对比测试中，初始温度为60 ℃的热水分别放置在恒温箱和普通EPP外卖箱内，20 min后恒温箱保温效率比普通外卖箱的高27.3%。结论 碳系水性电热油墨制成的发热器件具有低功耗和高加热性能的特点，应用于外卖恒温箱中提高了保温效果，有效减少外卖食物温度流失。     

基于半导体制冷的医用恒温箱的设计研究

医用恒温箱主要用于药品、试剂的储存,血液的冷藏保温等,它需要一个低温的恒温环境。本文以血液存储为背景,基于半导体制冷原理设计加工出一个医用恒温箱。首先用三维软件Solidworks 设计出箱体的三维模型,以此为依据加工出实体,然后采用继电器开关控制进行温度的恒温控制,进行实验验证,结果表明所设计的半导体制冷恒温箱,能够满足血液存储的恒温要求。     

一种外循环式温度恒温箱设计

现阶段,微小压力一般采用流体压强原理来进行测量,其中流体多采用水介质。测量中环境温度对水的密度有很大影响,进而对测量结果产生很大影响。本文从温度技术参数方面介绍了一种基于水介质外循环控温的恒温箱的设计,用于满足微压计量中对环境温度的要求。通过PID控温、温度控制箱体与外循环恒温水槽分离式结构设计,降低了温度控制箱内温度的瞬时波动,提高了温度的稳定性。经过试验验证,该恒温箱的温度均匀度能够达到0. 1℃,15h内温度波动优于0. 1℃,可以满足微压力测量中对环境温度的严苛要求。     

某过滤净化装置内部流场优化

使用CFD技术对某过滤净化装置内的流场均匀性进行优化研究,计算并分析不同工况下装置内部空气的流速,并利用正交试验方法设计模拟方案,研究不同导流板对装置内部流场的影响,确定最合理的导流板布置形式。采用正交试验对模拟结果进行分析,发现各因素影响水平从大到小分别为导流板数、导流板长度和送风量。在送风量一定的条件下,设置9块导流板,导流板长度为100 mm时装置内部的流场均匀性最好。     

环境试验箱内温度场均匀性的模拟与实验

在精密的电子元器件环境试验测试中,环境试验箱内的温度场均匀性、波动度等对测试效果的好坏至关重要。为了研究开发出高性能的环境试验箱,本文首先根据不同送、回风口型式（箱体构造）对速度场和温度场的影响,对箱体内结构进行了优化设计,在顺时针和逆时针箱体结构的基础上拓展了不同的结构型式;并对这些不同结构型式的箱体进行了模拟仿算,包括不同的送风口型式、角度和不同的回风口型式结构;对比仿真结果后,对圆形回风几何中心结构的箱体进行了实验验证。研究结果表明：七种不同的箱体结构模型中,0°倾角顺时针、几何中心位置逆时针以及多出风口模型三种模型的温度平均值和温度标准偏差都非常接近;实验和仿真数据在温度场均匀性标准偏差方面仍然存在一定的差距,所有测点平均温度为-71.55℃,温度误差为-1.55℃,最大温度偏差为1.8℃,但数据去中心化后,温度场各测点的温度具有相似的分布趋势。     

电除尘器气流分布模拟试验研究

电除尘器内进口断面气流分布均匀性和电除尘器内气流组织是影响电除尘器效率的主要因素。通过对除尘器的气流分布进行模拟试验,找出适合该除尘器的气流分布板形式,以确保除尘器稳定高效运行。     

一种新型多温区恒温箱均温性的数值模拟与实验验证

本文针对自行设计的一种新型的具有三个箱体的多温区恒温箱进行其均温性的研究。以多温区恒温箱的一个箱体为研究对象,建立了三维稳态数值模型,模拟了加热器情况不同时该箱体内的温度分布。结果表明,采用方形薄片加热器并布置于风机下方时,该箱体内的温度场最均匀。恒温箱三个箱体的加热器均采用上述情况后,对其设定了工况1(各箱体的设定温度分别为-15℃,-10℃,-5℃)和工况2(各箱体的设定温度分别为-20℃,-15℃,-10℃)进行实验。结果显示,工况1(即模拟工况)下的模拟值与实测值较吻合,最大误差为3.1%;两种工况下各箱体的温度均匀度最大为0.54℃。结果表明,在不同的测试工况下该多温区恒温箱各箱体内的温度分布都能维持均匀。     

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。