太阳能远红外综合干燥装置

本发明涉及的是一种将太阳能干燥技术与远红外干燥技术结合为一体的综合干燥装置,它适用于食品加工业中的农副土特产品的干燥,各种蜜饯、果脯、果品的干燥加工,以及一些中草药和肉制品的干燥加工. 以往的太阳能干燥装置大体上可分为四大类型:第一类是温室型; 第二类是集热器型;第三类是集热器和温室相结合的干燥装置;第四类是柱状抛物面聚光的管型干燥装置.上述各类太阳能干燥装置,由于单一地依靠太阳辐射能,干燥装置内温度随太阳辐射能强度的变化而变化,干燥温度和相对湿度无法控制,不能连续干燥,干燥装置内蓄热保温效果不理想.这种干燥装…     

半导体冰箱冷热端散热条件实验研究

半导体制冷器件是一种高热流密度元件,在红外测量、低温超导、生物医学、空间技术等领域有重要的应用,还可开发成专用制冷装置,适用于野外施工、勘探,考古以及郊游等户外活动食品饮料的保鲜,也可用于食品、饮料及医用疫苗等的冷藏。在给定工况下,通过改善半导体器件的冷热端散热条件,可使系统制冷量和制冷性能系数大幅提高。本文设计了实验装置,特别设计了8种实验工况对采用强迫对流换热和热端采用热管换热器散热的实际半导体制冷装置进行了实验分析,提出了改善半导体制冷元件散热条件的具体措施。     

问与答

<正> 一、温度对光学冷加工的影响如何? 理论和实践都证明了温度对光学冷加工的速度有着明显的影响,用相同的工艺参数进行冷加工是不能满足不同温度下的加工要求的。通过多年的实践我们给出了如下的不同温度下的冷加工曲线。     

稀土元素对铁的内耗的影响

本文对稀土元素含量(铈和镧含量的总和为:0,0.011,0.026,0.037,0.075,0.124％)不同的工业纯铁样品,在充分去碳、氮后进行了内耗测量。结果指出:铁的晶界激活能随稀土元素含量的变化出现极大值。这个极大值出现在稀土元素含量约0.03％左右,其值为11.3×10⁴卡/克分子,比不含稀土元素的铁样品(6.4×10⁴卡/克分子)约高一倍。对渗碳样品进行内耗测量得出:晶界内耗峰较充分去碳、氮样品的晶界内耗峰有近30℃的较大移动,各样品的晶界激活能趋近相等为7.6×10⁴卡/克分子(实验误差在±2000卡/克分子以内)。对碳在铁中的斯诺克峰的测量得出:随铁中稀土元素含量的增加,峰的高度被降低,而峰的位置和铁的比较,并没有变化。对各样品的冷加工内耗测量得出:未去碳和氮的原始样品(断面缩减率为88％)的冷加工内耗峰出现在230℃附近,峰值随稀土元素含量的增加而显著降低。对样品充分去碳、氮以后再重新渗氮,并进行冷加工(断面缩减率为88％),则冷加工内耗峰出现在190℃,这个峰也随着稀土元素含量的增加而显著降低。本文对于铁的这三个内耗峰(晶粒间界峰,斯诺克峰,冷加工峰)随着稀土元素含量而发生变化的可能原因,进行了初步的讨论。     

常用光学玻璃在冷加工抛光中的分类和抛光剂的应用系列

影响玻璃抛光的因素是极为复杂的。为避免玻璃抛光中存在的盲目性,提高生产效率,必须抓住影响玻璃的主要因素,以及对抛光剂的正确选择,本文就此讨论,并在生产实践的基础上,提出常用玻璃在冷加工抛光中的分类及适用于各种光学零件加工的抛光剂系列。     

食品辐射保藏原理及运用

应用辐射技术延长食品的保藏期，为食品保藏工作开辟了一条新的途径．用射线处理食品可以起到杀虫、灭菌、消毒、防霉和防腐以及抑制蔬菜、瓜果发芽变质的作用，达到降低农产品产后消耗、延长食品保藏时间、提高食品质量、增进食品卫生和改进某些食品的加工适应性的目的．本文论述了食品辐照装置、食品辐射保藏原理、食品辐射保藏效果以及辐射食品的安全卫生性等问题．     

铌钛铜合金的多因子实验设计法研究

一、引言 Nb-Ti合金是目前工业上用的一种超导材料,由于其加工性能良好,在超导装置中获得了广泛的应用.为了进一步提高Nb-Ti合金的超导性能,国内外最近在成分上用第三元素(例如铜等)合金化;在工艺上用冷加工和热处理多次交替进行处理,取得了较好的结果.     

高压脉冲电场技术在液体食品杀菌中的应用

利用高压脉冲电场技术对液体食品进行杀菌，可以在不破坏食品的营养结构与原有风味的基础上起到杀菌保鲜作用，本文介绍了杀菌装置的基本结构、杀菌机理、影响杀菌效果的基本因素和存在的关键问题。     

阿尔芬波加热托卡马克等离子体的能量平衡问题

本文用“剖面不变性”确定等效电子热导系数,研究了TCA装置上阿尔芬波加热的能量平衡,结果与实验符合很好。证明本文所用的方法对不同装置、不同加热方式都适用。     

原子光谱线位移机理的研究

在 0～ 80 0nm光谱范围 ,观察发现了原子光谱线位移与波长、温度、湿度及压力变化之间的非线性函数关系 ,绘制了它们之间的非线性函数关系曲线 ,给出了表达方程式 ;实验证实这些非线性函数关系对不同类型的光谱仪具有普遍适用性。观察发现了原子光谱线半宽度与温度变化之间的非线性函数关系。利用以上发现 ,开发了电感耦合等离子体光谱仪的智能波长校正装置和方法。实践证明 ,该装置和方法能有效地校正波长。     

Investigating the range of working temperatures of single-crystal piezoelectric elements based on crystals of the langasite family

The mechanical properties, thermophysical parameters, and thermal stabilities of the phase composition of crystals of the langasite family are studied. The results from examining the temperature dependences of the thermophysical parameters (thermal conductivity, thermal capacity, and thermal expansion coefficient), phase composition, and mechanical strength of crystals allows us to predict the operation of piezodevices based on crystals of the langasite family in the temperature range of 25–1000°С in high-temperature modern sensor acoustic and piezoelectric equipment.     

A method of controlled pulse heating: Applications

This paper is devoted to the state-of-the-art and technical potentials of the pulse heating method for the thin wire probe created in the Ural thermophysical school for studying the kinetics of spontaneous boiling and the related phenomenon of liquid attainable superheating. Special attention is paid to the search for technical means for controlling the power of the probe heating in a pulse experiment with the thermophysical properties of the substance taken into account. Applications of three particular cases are considered: techniques for the constant heating power, the thermal stabilization of the pulse-heated probe, and cooling of the shock-heated probe for investigating the behavior of multicomponent and high-molecular fluids essentially superheated above the temperature of phase equilibrium and/or temperature of molecule thermodestruction in a quasi-static process. Opportunities for application of the method are presented, in particular, for fast detection of volatile admixtures (including their traces) in high-molecular fluids, e.g., in oils of power equipment.     

纳米流体对流换热系数增大机理

纳米流体流动换热能力优于传统流体介质.研究了纳米流体热物性的提升和热散射对其对流换热系数的影响.结果表明,纳米颗粒的加入,优化了介质的热物性,增大了导热系数,强化了纳米流体内颗粒、流体以及流道管壁碰撞和相互作用,同时加强了流体的混合脉动和湍流,从而增大了对流换热系数. 关键词： 纳米流体 换热系数 热散射     

Phase diagram of aqueous solution at high pressure and low temperature

Abstract

This paper presents a constant mass high pressure isothermal calorimeter and describes the range of applications that this type of equipment can deal with. As an example, the thermophysical properties of an aqueous solution of MgSO₄ at low temperature and at high pressure have been investigated. The main results showed that the phase change heat of the solution decreased with increasing pressure and the phase change temperature of the eutectic concentration was depressed under high pressure. Those changes could be related to the MgSO₄ solubility and to water latent heat changes.     

Modeling the Effect of Thermophysical Properties on Pyrolysis of Intumescent Fire-retardant Materials

Thermophysical properties of intumescent fire-retardant (IFR) materials are important input parameters to simulate the pyrolysis process of IFR materials in fire scenarios. In this article, the effects of the thermophysical properties on pyrolysis of IFR materials are simulated based on a pyrolysis model of IFR materials. The selected thermophysical properties here are the specific heat capacity of the virgin material, thermal conductivity of the virgin material and char layer, heat of decomposition, density of virgin material, intumescent temperature, and surface emissivity of virgin material and char layer. Simulated mass loss rates (MLR) for the IFR materials at an incident heat flux of 50 kW/m² are investigated for the varied thermophysical parameter values. The results show that changes in these property values can affect the pyrolysis behavior of materials profoundly. Comparison with experimental results indicates that the simulations of MLR are in reasonably good agreement with the experiments.     

Effect of covalency,zero-point energy and charge transfer on the phase-transition,elastic and thermophysical properties of Ca-chalcogenides under compression

The pressure induced phase-transition, elastic and thermophysical properties of Ca-chalcogenides have been investigated by means of many body potential. The modified charge transfer potential consists of long-range Coulomb and charge-transfer interactions modified by covalency and short-range overlap repulsion extended up to second neighbours and zero-point energy effects. Another charge-transfer model excludes covalency and zero-point energy effects. These chalcogenides undergo first-order phase-transition at P _T = 39.23, 36.30 and 31.20 GPa and their equation of state show volume collapse of 10.12, 7.61 and 4.55% for CaS, CaSe and CaTe, respectively, which are in good agreement with the experiments. The elastic and thermophysical properties of these compounds have also been computed at normal and high pressures. Both the models are capable of explaining the Cauchy-discrepancy (C₁₂ ≠ C₄₄), elastic, phase-transition and thermophysical properties successfully.     

基于板式换热器的天然气冷却模拟与实验研究

结合实际工程项目,针对某新型天然气冷箱液化流程中的三台钎焊板式换热器,采用双通道耦合换热模型,以分段线性插值法计算天然气物性,基于FLUENT软件进行了天然气冷却换热过程的CFD数值模拟仿真,并开展了该新型冷箱的实验测试研究。将数值模拟计算结果与HSYSY工艺流程设计值以及实验测试结果进行对比。结果表明,数值模拟计算结果与HSYSY设计值平均误差为4.94%,证明了采用CFD数值模拟方法对HYSYS工艺流程设计与设备选型进行校核具有一定的参考价值。数值模拟计算结果与实验测试结果平均误差为7.78%,证明了数值模拟仿真所采用的简化假设、换热模型以及求解方法对于板式换热器天然气冷却换热过程是合理的。     

Methods of Determining the Characteristics of Dispersed Media at a Phase Transition

Gradient methods of determining the thermophysical characteristics of dispersed media at phase transitions are suggested. The reliability and the rate of convergence of the suggested methods are tested for a model problem. A comparison of the results of reconstructing the thermophysical characteristics by the numerical and conventional quasi-stationary methods demonstrates their good agreement. The influence of the number and arrangement of sensors on the accuracy of reconstruction of the thermophysical characteristics is studied.     

Analysis of conditions for determining the thermophysical characteristics of energetic materials by the laser pulse method

An analysis of conditions for determining the thermophysical characteristics of energetic materials by the laser pulse method is performed. Based on the results of numerical solution of the heat conduction problems for a sample of a material irradiated with a short heating laser pulse corresponding to actual experimental conditions, the time dependences on the sample surface temperature are determined. The heat pulse duration required to determine the thermophysical properties of materials and the ignition delay time are compared. It is shown that the determination of the thermophysical characteristics of a typical energetic material by the laser pulse method is possible at pulse durations of no longer than 0.24 s.     

Design of reinforced composites with a given set of effective thermophysical characteristics and some adjoining problems of diagnostics of their properties

A thermal conductivity model is proposed for an orthogonally reinforced fiber medium with dispersed hardening of the bonding agent. On its basis, the problem of the design of a composite with a given set of effective thermophysical properties is solved as well as the solutions are derived for some inverse problems of the diagnostics of thermophysical properties of phase materials and the reinforcement structure of a fiber composite from known effective thermophysical characteristics.