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《低温学》2018
A cryogenic oscillating heat pipe (OHP) made of a bended copper capillary tube is manufactured. The lengths of the condenser section, adiabatic section and evaporator section are 100, 280 and 100 mm, respectively. Neon is used as the working fluid. Effects of liquid filling ratio and condenser temperature on the thermal performance of the OHP are studied. A correlation based on the available experimental data sets is proposed to predict the thermal performance of the neon cryogenic OHP with different filling ratios and condenser temperature. Compared with the experimental data, the average standard deviation of the correlation is about 15.0%, and approximately 92.4% of deviations are within ±30%. 相似文献
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为了研究脉动热管用于冷却Mg B——2超导磁体的可行性,对一台自行研制的液氢温区脉动热管实验台开展了实验研究工作。充液率为34.2%时,随着加热功率的增大,脉动热管经历了启动、脉动、极限3个阶段,启动阶段中脉动热管传热温差波动很大,传热性能差,而脉动阶段中脉动热管传热温差很小,传热性能好。脉动热管在加热功率为1.28 W时具有最高的有效热导率为19 k W/m·K,此时蒸发段与冷凝段温差为0.28 K。 相似文献
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通过测试热管背板系统在不同进风温度、制冷剂冷凝单元(RCU)冷冻水进水温度及水流量工况下的换热能力,分析环境温度升高、系统供水不足等对高密度机柜服务器安全运行的影响,采用模拟负载机柜测试机房机柜安装热管背板后不同位置的换热能力。结果表明,热管背板系统对进风温度、冷冻水温度及流量具备良好的换热适应性,发热量大的服务器优先安装在机柜中下部,发热量小的服务器安装在机柜上部,可以最大限度发挥热管背板的换热能力。 相似文献
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Investigation of oscillating flow friction factor for cryocooler regenerator considering cryogenic temperature effect 总被引:1,自引:0,他引:1
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. 相似文献
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《低温学》2018
The pulsating heat pipe (PHP) is a potential alternative to highly conductive metals such as copper for long distance heat transfer. Effective thermal conductivity and heat transfer capacity of a PHP are two of the most critical factors for practical applications. In this paper, a helium based PHP, which consists of 48 parallel tubing sections, was developed. The lengths of the evaporator, adiabatic and condenser sections are 50 mm, 100 mm and 50 mm respectively. The condenser section was thermally anchored to a Gifford-McMahon cryocooler (GM cryocooler) with a cooling capacity of 1.5 W at 4.2 K. A maximum effective thermal conductivity of 12330 W/m∙K was obtained when 1.1 W heat was applied to the evaporator section at a fill ratio of 70.5%. With the same geometric parameters and operational parameters, the effect of the number of turns on the heat transfer performance was figured out by comparing the 48-turn PHP with an 8-turn PHP. The results show that the temperature difference between the evaporator and condenser sections of the 48-turn PHP is much smaller than that of the 8-turn PHP. The dry-out temperature response, effective thermal conductivity and heat transfer capacity of them are obtained and analyzed. Furthermore, two configurations of the 48-turn PHP, a parallel configuration and a series configuration, are defined. An optimum configuration is proposed and makes a reference to the design of a cryogenic PHP for applications. 相似文献
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B.F. Zhang 《低温学》1983,23(2):72
This paper describes a dummy test of a cryogenic heat pipe coupled between the infrared detector and cooler. The cryogenic heat pipe provides efficient thermal conduction for 2 W power over a 87.5 cm length with a maximum temperature difference of 0.91 K at 82 K operating temperature. The test results have useful applications. 相似文献
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深冷环路热管(CLHP)在正常工作之前,整个回路内工质处于超临界状态.通过对毛细芯在液体工质中良好的浸润,保证主蒸发器顺利启动.研究了从储气室位置、副蒸发器功率以及充装压力等影响超临界启动的因素对CLHP超临界启动过程的影响.结果表明:储气室的两种接入位置均能实现超临界启动过程;漏热量一定时,为了使主蒸发器达到启动条件,副蒸发器存在一个最小启动功率,且副蒸发器功率越大主蒸发器降温越迅速;对于回路结构一定的CLHP,当副蒸发器功率一定时,其存在一个最佳充装压力,在该充装条件下能使得启动过程最为迅速. 相似文献
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Abstract The performance of a sintered miniature heat pipe is enhanced. With the capillary limitation, porosity takes priority over the wick structure parameters that would affect the heat transfer capacity. Since sintered dendritic copper powder has higher porosity, it is used to mix with pore former (Na2CO3) in experiments for increasing porosity, and hence enhancing the thermal performance. The results show that, for a heat pipe with a 3mm outer diameter and 200 mm effective length, the heat transfer rate is up to 16.5W and the thermal resistance is 0.9°C/W. In comparison with the unmixed case, the performance increases about 40%. 相似文献
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为分析U形热管换热器的工作性能,通过改变迎面风速和回风温度,测出U形热管换热器前后的参数,计算换热温差和换热效率,然后测试相同条件下无U形热管换热器的状况,分析得出增加热管换热器后空调箱机组除湿量可提高15%左右。 相似文献
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本文试验研究了表面活性剂脉动热管的运行性能。采用浓度为0.125%的十六烷基三甲基溴化铵(CTAB)水溶液作为工质。试验结果表明,表面活性剂脉动热管的启动时间和启动温度随输入功率的增加而降低。脉动热管的传热特性与输入功率有关,且随着输入功率的增加而增强。与纯水脉动热管相比,充液率为50%的CTAB脉动热管在加热功率100 W时热阻降低52%。 相似文献
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《低温学》2015
Sufficient knowledge of thermal performance and pressurization behaviors in cryogenic tanks during rocket launching period is of importance to the design and optimization of a pressurization system. In this paper, ground experiments with liquid oxygen (LO2) as the cryogenic propellant, high-temperature helium exceeding 600 K as the pressurant gas, and radial diffuser and anti-cone diffuser respectively at the tank inlet were performed. The pressurant gas requirements, axial and radial temperature distributions, and energy distributions inside the propellant tank were obtained and analyzed to evaluate the comprehensive performance of the pressurization system. It was found that the pressurization system with high-temperature helium as the pressurant gas could work well that the tank pressure was controlled within a specified range and a stable discharging liquid rate was achieved. For the radial diffuser case, the injected gas had a direct impact on the tank inner wall. The severe gas-wall heat transfer resulted in about 59% of the total input energy absorbed by the tank wall. For the pressurization case with anti-cone diffuser, the direct impact of high-temperature gas flowing toward the liquid surface resulted in a greater deal of energy transferred to the liquid propellant, and the percentage even reached up to 38%. Moreover, both of the two cases showed that the proportion of energy left in ullage to the total input energy was quite small, and the percentage was only about 22–24%. This may indicate that a more efficient diffuser should be developed to improve the pressurization effect. Generally, the present experimental results are beneficial to the design and optimization of the pressurization system with high-temperature gas supplying the pressurization effect. 相似文献
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Results are given of experimental investigations of an oscillating heat pipe (OHP) made in the form of a closed-loop coil of a copper capillary tube with an inside diameter of 2 mm, 4.5 m long, and filled with water in an amount of 50% of internal volume. The starting characteristics of OHP are studied in the range of heat loads from 30 to 100 W under conditions of cooling by way of natural and forced air convection. The pattern of temperature pulsations in the zones of heating, heat transport, and cooling is investigated. It is found that temperature pulsations exhibit a chaotic pattern. In cooling of an OHP by way of natural convection, the increase in heat load is accompanied by an increase in the maximal temperature of the heating zone with a simultaneous decrease in the nonuniformity of the temperature field. When an OHP is cooled by way of forced convection, a decrease in the maximal temperature of the heating zone is observed; however, this is accompanied by an increase in the amplitude of temperature pulsations and in the nonuniformity of the temperature field. 相似文献