Investigation of oscillating flow friction factor for cryocooler regenerator considering cryogenic temperature effect

In this paper, experimental results and correlations on the friction factor of screen regenerators are presented, being focused on the effect of cryogenic temperature. Cryogenic environment of helium gas is simulated by performing a simple room-temperature experiment using a higher density gas. Based on the experimental results, the proper correlations are proposed with several non-dimensional parameters. Numerical simulation results from the model with the proposed friction factor are compared to the experimental data under actual operating condition of cryocoolers. The experimental data confirm the accuracy and the availability of the proposed friction factor.     

Thermoacoustic power effect on the refrigeration performance of thermal separators

An experimental investigation on the refrigeration processes occurring in a receiving tube of a thermal separator was conducted in order to determine the primary factors affecting the refrigeration performance of this new type of refrigerator. In the current investigation, the gas in the system is divided into the oscillating gas and driving gas. While the compression/expansion of the oscillating gas caused by the driving gas determines the refrigeration process occurring in the receiving tube of the thermal separator, the temperature gradient on the receiving tube significantly affects the acoustic power generation and refrigeration performance. Experimental results demonstrate that when the tube-wall temperature difference near the open end of the receiving tube increases, the refrigeration coefficient increases. Using the information presented in the paper, a new cryogenic refrigeration system was developed, and the experimental data shows that the temperature of the cryogenic air flow in the system could reach −130 °C within 50 min. It suggests that the thermal separator investigated in the paper can be employed in the field of cryogenic engineering.     

Investigation of the effects of three key parameters on the heat transfer capability of a CLHP

A cryogenic loop heat pipe (CLHP) has been developed for future aerospace applications at the TIPC (Technical Institute of Physics and Chemistry). The device has been tested in different situations with constant heat sink temperature of about 78 K. The effects of the reservoir volume and the pore size of the primary wick on the performance of CLHP were investigated. With a wick pore size of 2 μm, the CLHP can transfer a heat load of 26 W under horizontal orientation no matter what size of the reservoir volume being used. On the contrary, when the pore size was large (10 μm), the heat transfer capability of the CLHP can be up to 26 W only when a smaller reservoir (60 cc) was used, and its ability to operate against gravity was greatly weakened. Moreover, when the working fluid was oxygen instead of nitrogen, the heat transfer capability can be up to 50 W under horizontal orientation with the other experimental conditions remaining the same.     

低温热管的最新研究进展

作为一种高效传热方式，低温热管可望在空间探索、超导磁体冷却等方面获得广泛应用。简要介绍了低温热管的工作原理，着重分析了各种传热极限对低温热管性能的影响，总结了近几年低温热管研究与应用的最新发展情况。     

低温热虹吸管传热性能的初步研究

作为一种高效传热方式,低温热管可望在空间探索、超导磁体冷却等方面获得广泛应用.介绍了低温热虹吸管的设计过程,实验分析了低温热虹吸管的工质质量、倾斜角度对低温热虹吸管传热性能的影响.研制的低温热虹吸管平均传热能力达2 W/K.     

热管及其主要应用领域的研究

热管是一种超导热体的传热元件,具有传热系数高、温度分布均匀、热响应迅速、结构紧凑、工作可靠等优点.本文介绍了热管的工作原理、结构,重点阐述了热管式散热器在一些领域里的应用,并作了性能的分析和研究,最后介绍了热管在电机领域里的有望广泛应用.     

Exploring the depths of Kraken Mare – Power,thermal analysis,and ballast control for the Saturn Titan submarine

To explore the depths of the hydrocarbon rich seas on the Saturn moon Titan, a conceptual design of an unmanned submarine concept was recently developed for a Phase I NASA Innovative Advanced Concept (NIAC) study. Data from Cassini Huygens indicates that the Titan polar environment sustains stable seas of variable concentrations of ethane, methane, and nitrogen, with a surface temperature around 93 K. To meet science exploration objectives, the submarine must operate autonomously, study atmosphere/sea exchange, interact with the seabed at pressures up to 10 atm, traverse large distances with limited energy, hover at the surface and at any depth within the sea, and be capable of tolerating multiple different concentration levels of hydrocarbons. Therefore Titan presents many cryogenic design challenges. This paper presents the trade studies with emphasis on the preliminary design of the power, thermal, and ballast control subsystems for the Saturn Titan submarine.     

用于CPU冷却的集成热管散热器

提出了将立体蒸汽腔和热管两相传热结合,用于CPU冷却的集成热管散热器新概念,并对设计出的集成热管散热器的传热性能和整体的均温性进行了试验研究.试验结果表明,未优化的集成热管散热器的热阻在0.14℃/W～0.2℃/W之间,且整个散热器具有均匀的温度分布.与当前的热管散热器相比,这种结构的集成热管散热器具有散热效率高、结构紧凑、接触热阻小、重量轻、成本低等特点,可以满足未来大功率CPU散热的要求.     

热管在热泵干燥器中应用的研究

依据质量平衡和能量平衡规律,建立了带热管回热器的热泵干燥器数学模型,该模型由热管,干燥室,蒸发器,压缩机和冷凝器五大模块组成,利用此模型对系统的性能参数及运行规律进行了模拟研究。同时,对模拟所得到的部分结果做了实验验证。     

Geysering inhibiting research for single feeding-line in cryogenic propellant transfer system

The main purpose of this paper is to use an external recirculation pipe to inhibit geysering phenomenon in cryogenic propellant transfer system. Inhibiting geysering phenomena in the long vertical cryogenic feeding-line is very important to both the system designers and the operators because they may be latent catastrophic failure(s). Separated-flow model has been used in numerical simulation. Considered the numerical simulation results and the experimental conditions, an experimental set-up using liquid nitrogen (LN₂) as working fluid has been built to simulate the recirculation in the long vertical cryogenic feeding-line.From the experimental results, it is clear that the natural circulation occurs in the recirculation system utilizing the external recirculation pipe and geysering phenomenon is inhibited. Adding external recirculation pipe to normal feeding-line system can be an effective method to reduce or eliminate geysering in cryogenic propellant transfer system.     

热管恒温槽校准工业用短型温度计的可行性研究

在(200~500)℃范围内,热管恒温槽是一种替代油槽和盐槽的清洁恒温源。受传热效率的限制,热管恒温槽在校准短型温度计时会产生较大的偏差。本文从传热学角度分析了短型温度计校准中偏差产生的原因。分析证明,在校准过程中,通过增大接触面积,提高换热系数的方式可以有效强化传热,减小因传热造成的偏差。实验表明,通过增加辅助金属环的方式能够有效提高传热效率,提高测量准确度,降低对被测温度计浸没深度的要求,完成工业用短型温度计的校准。     

用热管回收余热作热源的溴化锂冷热水机组

该文介绍了一种能回收利用工业废气制冷和制热的溴化锂冷热水机组；采用高效的“水-碳钢“热管换热器，传热效率高；分析了节能效果，论证了本机组有较好的节能效果。本机组可推广到很多具有废热可用的场合，具有很好的经济效益。     

槽道热管在加快低温回路热管主蒸发器降温过程中作用的实验研究

介绍液氮温区低温回路热管结构设计的1种方案.首次采用槽道热管作为低温回路热管的次蒸发器,并对其在加快主蒸发器降温过程中的作用进行了详尽的实验研究.这种次蒸发器的结构简单,并使低温回路热管的整体设计变得简易.实验表明,经过合理的阻力设计,槽道热管形式的次蒸发器能起到加快主蒸发器降温的作用,为研究低温回路热管的传热特性提供了前提条件.     

热管在多联机卡式天花室内机中的应用

以某品牌多联机3个型号卡式天花室内机为例,将热管技术应用于多联机卡式天花室内机,计算不同室内设计温度条件下的换热量。研究结果表明,与传统多联机室内机相比,其节能率可达28.46%~68.53%,同时在无需电加热或蒸汽动力设备的条件下提高室内送风温度,在节约能源消耗的同时满足室内人体热舒适的要求。     

倾角与冷却水温度对新型闭式重力热管换热器传热性能影响

本文以丙酮为工作流体,设计了一套新型重力热管换热器,该装置由五根底部连通的垂直蒸发管共用一根水平同心套管冷凝管构成。采用理论和实验相结合的研究方法,分析了装置的传热性能,并对其结构参数进行优化。研究了当倾斜角度为15°~90°、操作温度为40~80℃、冷却水温度为10~30℃时装置的传热性能。结果表明:新型重力热管换热器具有良好的等温性能及操作稳定性;当充液率为15%、倾斜角度为60°、冷却水温度为30℃时,换热器达到最佳工作状态;最大传热量可达1 700 W左右,此时平均热阻为0.042℃/W。     

热泵驱动热管式辐射供热装置的实验研究

本文提出热泵驱动热管式辐射供热装置的循环原理,基于1 HP压缩机研制出一套样机,并在焓差室测试了样机在室内温度为18～22℃,室外温度为-15～0℃的工况下的运行特性。结果表明:热管散热器启动迅速、表面温度分布均匀,热管工质的最佳充注比率为0.1,当室内温度为22℃,室外温度为-15～0℃时,制热COP最高可达4.1。