半导体制冷器件原理及其应用

在功率较小的温度控制系统中,可以广泛运用半导体制冷,因为它在制冷时,没有污染、可靠性非常强。例如便携式汽车冷暖箱、冷热饮水机、微机芯片的制冷等。本文详细叙述了半导体制冷片(器件)的工作原理、工作过程及其特点,并研究开发了一套以单片机STC12C5A60S2控制为核心,数字式温度传感器,半导体制冷片以及固态继电器配合使用的微机芯片温度检测制冷控制系统。该系统具有很强的实用性和可移植性。     

Calculating the Refrigeration Coefficient by Using the Second Law of Thermodynamics

Refrigeration coefficient, ε, is usually calculatedby using the First Law of Thermodynamics. In this paper, anew derivation process is introduced through the combinationof the Second Law of Thermodynamics with the First Law of Thermodynamics. As a result, two new calculationequations for refrigeration coefficient are proposed. Oneequation is equivalent to the common method, but its form isa little complicated for real calculation. Another equation is the further simplification, and can be used to calculate therefrigeration coefficient instead of common method with apermit error.     

二维流动模型用于喷射器关键结构设计分析

在试验验证了喷射器二维可压缩流动模型可行性和计算准确性的基础上,应用该模型对喷射器结构与性能和流场之间的变化关系进行了研究．试验结果表明,二维流动模型在没有引入经验参数的条件下,能够较好地预测喷射器的工作特性和性能指标．喷射器内流场直观地显示了混合室截面大小对喷射器性能的影响过程．     

Applications of membrane distillation technology in energy transformation process-basis and prospect

Membrane distillation technology is a new type of efficient separation technology that combines traditional distillation technology and membrane separation technology. In the study, applications of membrane distillation technology in thermal engineering and refrigerating engineering with typical energy transformation process were presented. Desorption and regeneration process of saline solution by vacuum membrane distillation was proposed on the basis of the concentration and separation properties of membrane distillation. Membrane distillation technology could be used in lithium bromide absorption refrigeration system, energy storage system, and the regeneration process of liquid desiccant solution in temperature-humidity independent control air-conditioning system. The aim of the applications was to use the low-grade energy such as waste heat, solar energy and geothermal energy adequately and to improve the available temperature difference of heat source. According to latent heat transfer and thermal conduction across the membrane in direct contact membrane distillation process, a novel membrane heat exchanger with both heat transfer and mass transfer processes was proposed. The heat exchanger could be used as the solution heat exchanger of lithium bromide absorption refrigeration system and as the special heat exchanger that recovered heat and pure water simultaneously. Some feasible process flows about the applications of membrane distillation technology to energy transformation process were listed and analyzed. Finally, future research emphases were indicated.     

准同型相界钛酸铋钠基铁电固溶体的电卡效应研究

利用铁电材料的电卡效应实现致冷成为当前国内外的研究热点之一.基于Maxwell关系,围绕着准同型相界组分的Bi0.5Na0.5Ti O3基无铅铁电固溶体,研究了其电卡效应,结果表明:该体系在5 k V/mm的外电场下,显示出优异的致冷特性,温度的变化量可达到1.15 K,相应的致冷强度可达0.23 K·mm/k V,在全新的固态致冷器件中显示出应用前景.     

制冷空调系统仿真中工质热物性计算模块设计

根据制冷空调系统仿真的特点,以状态方程法建立了制冷剂热力性质计算模块并进行了实用化的编程.程序采用V 6.0面向对象的程序设计语言,具有良好的人机界面,运行可靠,使用方便.将该模块的计算结果与制冷剂热物性标准图表进行比较,表明其精度高,能满足制冷空调系统仿真的需要.     

跨临界CO2蒸气压缩/喷射制冷循环理论分析

对跨临界CO2蒸气压缩/喷射制冷循环的理论研究,特别是对喷射器工作特性进行数值模拟,有助于改善实验系统的制冷性能。使用动量守恒和能量守恒方程建立了喷射器模型,同时考虑了系统稳态下喷射器出口干度和喷射系数的耦合关系。比较了不同的CO2冷却放热压力、蒸发温度、喷射器喷嘴效率和扩压效率等对理论循环性能的影响。理论分析表明:优化的喷射系数能显著改善制冷循环性能,蒸发温度和CO2冷却放热压力对系统性能的影响比较大,系统性能系数和喷射器喷射系数对喷射器的喷嘴效率和扩压效率的变化不敏感。     

基于并行感知器的制冷系统故障诊断分析

选择热力参数集组成反映制冷系统故障状态的特征向量,提出一种并行感知器神经网络,通过模式分类来尝试联系系统故障状态与热力参数特征向量之间的映射关系.对故障模拟实验结果的应用表明,基于并行感知器网络的诊断方法可行且有效,为开发以人工神经网络为框架的制冷系统故障诊断系统提供了研究基础.     

瞬时热探针法测量沸石复合吸附剂导热系数

应用瞬时热探针法测试吸附制冷工质导热系数,在不同的吸附量下对配置出的复合吸附剂导热系数进行测试,并从中选出适用于太阳能冷管的复合吸附剂Z1和Z2.试验结果表明:在同一吸附量的情况下,导热系数与其添加的粘结剂含量正相关,并且在w=0%~7.5%的添加粘结剂范围内导热系数随着粘结剂含量增加而显著增加;13X沸石原粉、复合吸附剂样品Z1和Z2的导热系数随其吸附量增加呈近似线性增长,当吸附量从0%增加到25%时,各吸附剂导热系数均增加了150%以上;配置出复合吸附剂Z1和Z2在分别添加w=5.0%和7.5%的添加剂下,平均导热系数分别为0.183和0.199 W/(m.K),比13X原粉分别提高65.4%和80.1%;将配置的复合吸附剂Z2应用于太阳能冷管,其制冷系数COP约为0.24~0.28.     

不同热端温度条件下的两级制冷片性能分析

在热电堆数量比n及无量纲电流j变化的条件下,对两级热电制冷器在不同热端温度T_h条件下进行性能分析.通过分析不同热端温度条件下净制冷量q^*和制冷系数COP的表达式,对参数n,j进行优化,给出了不同优化要求条件下n,j的取值范围.