露点间接蒸发冷却技术的研究进展及现状分析

露点间接蒸发冷却技术是一种能将冷却器的入口空气降到对应的露点状态的水蒸发冷却技术,具有较高的研究意义及广阔的应用前景。根据目前这一技术的研发情况,本文较为详细地介绍露点间接蒸发冷却相关的最新研究进展,提出直流式、叉流式和逆流式露点间接蒸发冷却器3种基本结构。考虑其作为制冷通风空调的一种,送风状态是受到限制的,结合露点间接蒸发冷却技术固有的特点,对其送风状态进行分析,并说明这种冷却器的应用条件及场合。     

露点间接蒸发冷却技术的研究进展及

露点间接蒸发冷却技术是一种能将冷却器的入口空气降到对应的露点状态的水蒸发冷却技术,具有较高的研究意义及广阔的应用前景.根据目前这一技术的研发情况,本文较为详细地介绍露点间接蒸发冷却相关的最新研究进展,提出直流式、叉流式和逆流式露点间接蒸发冷却器3种基本结构.考虑其作为制冷通风空调的一种,送风状态是受到限制的,结合露点间接蒸发冷却技术固有的特点,对其送风状态进行分析,并说明这种冷却器的应用条件及场合.     

露点间接-直接蒸发冷却空调机组的应用研究

针对目前常见露点间接蒸发冷却器存在的不足,提出露点间接-直接蒸发冷却空调机组,从露点间接段的结构上对露点间接蒸发冷却器进行优化设计。并在福州地区搭建实验台,研究高湿度地区露点间接-直接蒸发冷却空调的应用。测试结果表明,此空调机组在福州地区的温降可以高达10.24℃,低于湿球温度,接近露点温度。     

多孔功能陶瓷露点板翅式间接蒸发冷却器设计探讨

对国内外几种露点间接蒸发冷却器的材料进行比较,简要阐述非饱和多孔介质的输运机制。描述多孔功能陶瓷露点板翅式间接蒸发冷却器的结构和工作原理,探讨该冷却器的特点,并分析该冷却器的应用前景。     

基于露点板式间接蒸发冷却器空调机组特性的探讨

通过对目前国内外露点间接蒸发冷却技术的发展进行介绍,提出一种基于露点板式间接蒸发冷却器的空调机组—露点间接—直接蒸发冷却空调机组。并对此空调机组的原理和特性进行了分析,结果表明这种空调机组与传统露点间接蒸发冷却器相比,温降幅度大,可以进一步逼近室外空气的露点温度,是露点间接蒸发冷却技术的一个新发展。同时还对这一机组的性能测试提出了一些研究方法。     

多孔陶瓷管式露点间接蒸发冷却器实验台设计研究

针对间接蒸发冷却器壁面亲水性的问题,提出采用多孔陶瓷材料,设计和搭建了多孔陶瓷管式露点间接蒸发冷却器实验台,并简述了实验台的运行过程。该实验台的搭建对多孔陶瓷管式露点间接蒸发冷却器的性能测试起着至关重要的作用。     

露点间接蒸发冷却开式空调系统的介绍和应用

介绍了露点间接蒸发冷却技术的原理,比较分析了露点间接蒸发冷却器的三种结构形式;然后将该技术应用于实际中,结合气幕伞的结构,设计了露点间接蒸发冷却开式空调系统;对其进行了测试,结果显示系统可降温9-14℃。此系统在中等湿度以下的地区有很好的应用前景。     

配置露点蒸发器的新型空气制冷循环的热力分析

本文提出一种与露点间接蒸发冷却器相耦合的冷库用新型空气制冷循环。对该新型循环进行了相应的热力计算,与普通空气制冷循环及NH3蒸气压缩循环进行了对比分析,并对比分析了工况参数变化对耦合露点间接蒸发冷却器前后的空气制冷循环性能及NH3蒸气压缩循环COP的影响。结果表明:配置露点间接蒸发冷却器的新型空气制冷循环的性能得到了提高,设定工况下最大COP可提高37.8%,且相比NH3制冷循环,流程与设备更简单。     

露点间接蒸发冷却器的应用分析

论述露点间接蒸发冷却器的原理和空气流程,并对冷却器进行实验室应用测试分析及其与机械制冷结合应用的实际工程测试,得出以下结论：在西安地区可使送风温度降低7～10℃,冷却效率达85％以上,在3000m^3／h风量下压降只有185Pa;在浙江地区使用露点间接蒸发冷却与机械制冷相结合技术的空调机组,可使蒸发冷却段送风温度降低6～8℃,空调系统节能14．3％;相同测试条件下,露点式比管式或热管式的冷却效率高10％以上。     

逆流波纹板式露点蒸发冷却器的数值模拟研究

本文对逆流波纹板式露点蒸发冷却器的性能进行了数值模拟,并通过实验验证了数值模拟的准确性。通过数值模拟,研究了二次/一次风量比、一次风风速、循环水流量、进风参数、结构参数(通道间距和通道长度)对露点蒸发冷却空调器性能的影响。结果表明:当二次/一次风量比为0. 3～0. 4,一次风速为2～2. 7 m/s,通道间距为4. 3 mm,通道长度为1 m时,露点蒸发冷却空调器冷却效率及COP均较高;随着循环水质量流量的增加,送风温度升高,冷却效率及COP均下降,因此在湿通道表面完全润湿条件下,循环水质量流量越小,露点蒸发冷却器性能越好。湿球效率主要受露点蒸发冷却器结构及运行参数的影响,该逆流波纹板式露点蒸发冷却器的湿球效率在110%～115%之间。     

斯特林制冷机回热器热损研究

讨论了回热器的各种损失对斯特林制冷机的影响,对斯特林制冷机回热器的结构和丝网填料进行了分析,并模拟分析各种损失的影响.研究表明,回热器的结构、丝网填料对制冷机的性能有重大影响.     

Performance improvement of a transcritical CO2 refrigeration cycle using two-stage thermoelectric modules in sub-cooler and gas cooler

A novel integration of a trans-critical CO₂ refrigeration cycle with thermoelectric modules in the gas cooler and sub-cooler is presented, wherein a two-stage thermoelectric generator (TEG) produces power from the waste heat of gas cooler, which is a considerable amount of required power in two-stage thermoelectric cooler (TEC) to sub-cool the refrigerant before expansion device. Mathematical simulation of TEG and TEC as well as energy and exergy based thermodynamic analysis of the proposed system is performed, and the effects of some important parameters on the system performance are investigated. A comparison is carried out between the proposed system and the simple CO₂ refrigeration cycle, indicating that the proposed configuration improves the coefficient of performance (COP) about 19%. Also, it is observed that the TEC and TEG have better performance in a two-stage configuration. The parametric study reveals that the new configuration decreases the cycle operation pressure at maximum COP and exergetic efficiency.     

Thermal performance of the CrIS passive cryocooler

The configuration, performance, and test validation of a passive radiant cooler for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Crosstrack Infrared Sounder (CrIS) Instrument are presented. The cooler is required to provide cryogenic operation of IR focal planes. The 11 kg device, based on prior ITT Industries Space Systems Division coolers, requires virtually no power. It uses multiple thermally isolated cooling stages, each with an independent cryoradiator, operating at successively colder temperatures. The coldest stage, with a controlled set point at 81 K, cools a longwave IR (LWIR) focal plane. An intermediate stage, with a 98 K control point, cools detectors operating in MWIR and SWIR spectral regions. The warmest stage includes a fixed, integral earth shield that limits the thermal load from the earth in the NPOESS Operational Low-earth Orbiting (LEO) orbit. A study of the thermal balance and loads analysis used to evaluate the predicted cooler performance is discussed. High performance margins have been retained throughout the cooler development, fabrication and test phases of the program. The achievable in-orbit temperatures for this cooler are anticipated to be 73 K for the LWIR cooling stage and 91 K for the midwave IR (MWIR)/shortwave IR (SWIR) stage. Test results from two iterations of thermal vacuum verification testing are presented. Lessons learned from the first test, which failed to produce the predicted performance are included. The thermal model of the cooler and test configuration was used to identify deficiencies in the test targets resulting in unexpected heat loads. Corrective action was implemented to remove the heat leaks and a second test verified both the cooler performance and the correlation of the detailed thermal model.     

An innovative configuration for thermoacoustically-driven pulse tube coolers

Obtainable lowest temperature of a thermoacoustically-driven pulse tube cooler is generally limited by the pressure ratio provided by the thermoacoustic engine with helium as working gas. It is also known that a thermoacoustic engine filled with nitrogen can generally provide much larger pressure ratio and lower frequency than the same engine filled with helium. Here we introduce an innovative system configuration which uses an elastic membrane as the interface between the thermoacoustic engine subsystem and the pulse tube cooler subsystem. The membrane can transport acoustic work from the engine to the cooler, and meanwhile separate the working gases used in respective subsystems. Through this way, it is possible for the engine to operate with nitrogen to provide larger pressure ratio and more suitable frequency for the pulse tube cooler which can still use helium as the working gas. To test this idea, a thermoacoustically-driven pulse tube cooler was built. With the innovative configuration, the pulse tube cooler reached a lowest temperature of 139 K. On the other hand, without the membrane, the PTC only achieved a lowest temperature of 186 K when using nitrogen and 145 K with helium for both the PTC and the engine.     

翅片管式CO2气体冷却器模拟与优化

为了研究CO2在翅片管式气体冷却器内的流动特性,建立了稳态分布参数模型,并进行了实验验证。结果表明:CO2侧换热系数受入口压力和质量流量的影响较大,但入口温度对其影响很小。换热量随着入口压力的变化有一个最大值;且随着流量的增大,最大换热量所对应的入口压力值逐渐增大。压降和换热量均随入口温度的增加而线性增加。适当增加管程数,采用较小管径的气冷器性能更高。     

Low-frequency magnetic interference in a SQUID gradiometer caused by a Cryotiger gas-mixture cooler

A Cryotiger^® gas-mixture cooler was applied for cooling of three high-T_c SQUID magnetometers. These SQUID magnetometers were mounted on an alumina holder in an axial gradiometer configuration. From 20 Hz upward, the system noise was about 0.1 pT/√Hz. Below this frequency, the noise gradually increased to a level of 10 pT/√Hz at 1 Hz. This low-frequency excess noise appeared to be due to remnant magnetization of the Cryotiger cold head. Movement of magnetic cold-head parts with respect to the SQUIDs are induced by pressure fluctuations in the heat exchanger lines. By using one SQUID as a reference for the cooler noise, a first-order gradiometer can be formed in which the cooler noise is eliminated. To establish a proper second-order gradiometer either a fourth SQUID has to be added, or the spatial separation between cold head and SQUIDs has to be increased significantly.     

300 Hz脉冲管制冷机特性研究

从实验和数值计算两个方面研究了1台工作频率为300 Hz的单级脉冲管制冷机的制冷特性.实验方面,验证了平均压力、入口压比、惯性管长度以及均流化元件对其制冷性能的影响,该制冷机在平均压力为3.96 MPa、入口压比为1.21时获得了79.6 K的最低制冷温度;数值计算方面,基于线性热声理论的模拟结果与实验结果进行了比较,以验证程序的有效性.     

Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters: Part I - Experiments

An experimental and analytical study on the performance of a compact, microchannel water- carbon dioxide (CO₂) gas cooler was conducted. The gas cooler design under investigation used an array of serpentine refrigerant microchannel tubes wrapped around water passages containing offset strip fins, resulting in a generally counterflow configuration between the two fluids. Part I of this two-part paper addresses the experimental aspects. Data were obtained using an experimental heat pump facility at varying inlet conditions for three gas coolers of the same design, but different sizes. Measured heating capacity for the three gas coolers ranged from 1.5 to 6.5 kW. The results of this study are used in the companion paper (Part II) to develop a predictive heat exchanger model to optimize gas cooler design over a wide range of operating conditions, eliminating the need for expensive prototype development and testing.