【作者】 蒋彦龙；

【导师】 陈国邦；

【作者基本信息】 浙江大学 ， 制冷与低温工程， 2003， 博士

【摘要】 作为一种新型的小型低温制冷机，脉管制冷机由于冷头没有运动部件，具有制造简单、寿命长、自干扰震动小等突出优点，一直以来是研究的热点，在过去十多年取得了巨大进展。然而，由于脉管制冷机效率至今仍低于传统的低温制冷机(如G-M制冷机、斯特林制冷机等)，从而限制了它的广泛应用。如何进一步提高制冷效率和可靠性是它得以广泛应用的首要前提。本文首先回顾了脉管制冷机的发展历史和最新研究进展，在此基础上从直流抑制和工质选取两个角度出发，开展了高性能G-M型单级脉管制冷机的研究工作。具体内容介绍如下： 1．直流机理研究和抑制方法探讨 双向进气脉管制冷机中存在的直流流动不仅造成了大量的冷损，限制了制冷机性能的进一步提高，同时还是引起制冷温度不稳定的根本原因。从流体网络理论出发，对直流形成机理和抑制方法进行了深入研究。 2．直流抑制和脉管制冷特性实验研究 在对各种直流抑制方法深入比较的基础上，积极利用双向进气调相结构具有调相和调幅的双重功能，采用了新型双阀双向进气结构对直流进行抑制。在2kW(RW2)和4kW(CP4000)压缩机驱动时分别获得了18.7K和14.7K的最低制冷温度，对应在30K时的制冷量为分别为11.5W和29.5W，突破了目前单级脉管制冷机最低制冷温度维持在20K附近的限制。 3．回热器流阻对脉管制冷机稳定性的影响 理论和实验研究了通过改变回热器流阻进行直流抑制的可行性，结果表明：适当增加回热器流阻，可以有效抑制直流，从而进一步改善了脉管制冷机性能，实现双向进气脉管制冷机在较高温区长时间地稳定工作，为目前采用双向进气结构存在的高温区性能不稳定提供了新的解决途径。浙江大学博士学位论文蒋彦龙:高性能G一M型单级脉管制冷机研究2003年5月4.氦氢混合工质脉管制冷特性实验研究 利用氢工质优越的传热和流动特性，从氦氢混合工质对回热器流阻、冷端换热器传热性能和工质膨胀效率等因素的影响角度出发，开展了30K温区氦氢混合工质脉管制冷实验研究。实验结果表明，采用组分为O一25%的氦氢混合物能够在一定程度上提高脉管制冷机性能。其中，采用含氢10%的混合工质，可以获得高出纯氦5.2%的制冷量和4.9%的COP。此外，在一台二级脉管制冷机上的实验结果表明，采用氦氢混合物在30K温区的制冷量和COP明显高于相同条件下纯氦的值，工质对二级脉管制冷性能的积极影响大于单级机。5.脉管制冷氮液化器性能实验研究 为了满足许多应用场合对少量低温液体的使用要求，开展了用脉管制冷的氮液化器性能实验研究，对不同工作模式下的系统液化速率、降温和复温特性进行了考察。结果表明，在实验的单级脉管制冷机中采用小孔和双向进气工作模式的系统氮液化率分别为7.68L/d和10.92L/d;此外，利用工质相变条件下温度维持不变的特性，可以实现在制冷机关机后相当长的时间内维持系统冷端温度不变，这一特性在超导器件冷却方面具有重要的应用价值。更多还原

【Abstract】 Unlike the Stirling or Gifford-McMahon refrigerators, the pulse tube cooler (PTC) has no moving parts at the cold end. The lack of cold moving parts has allowed it to solve some of the problems associated with cryocoolers in many different applications, such as vibration and reliability. In the past ten years, great progress has been made on the development of the PTC. However, its efficiency is still lower than that of the traditional cryocoolers, which is one of the barriers to further development of this refrigeration method. To insure a commercial success of the PTC by replacement of conventional GM- or Stirling-coolers in most of their applications, it is of major importance to optimize the PTC and to demonstrate performances and efficiencies as close as possible to those known for the conventional cryocoolers. After a detailed review on the recent development of the pulse tube cooler, the present work focuses on the following objects:1) DC flow and its suppressionThe DC flow will appear for the introduction of the double-inlet in a pulse tube cooler. It greatly deteriorates the cooling capacity as well as leads to temperature instability under high heat load of the cooler. From the fluid network theory, the root of the DC flow in a double-inlet pulse tube cooler is theoretically investigated. Some suppression ways are briefly described.2) Experimental investigation on DC flow suppression and refrigeration characteristicsBased on the detailed analysis and comparisons for all kinds of the suppression methods, two parallel-placed needle valves with opposite flow direction referred as two-valved configuration instead of traditional single-valved configuration as double-inlet are introduced in experiments to eliminate the DC flow and are proved to be a successful way. Driven by RW2 and CP4000, 18.4K and 14.7K no load temperature has been reached respectively and11. 5W and 29. 5W cooling-power at 30K could be obtained. Meanwhile, the effect of the regenerator matrix on the performance of the cooler under different operation modes has been extensively investigated.3) Influence of Regenerator Flow Resistance on Stability of the PTCThe feasibility of an increased regenerator flow resistance to suppress the DC flow is experimentally and theoretically investigated. Results show that an increased flow resistance of the regenerator leads to a reduction and stabilization of the disturbing DC-flow in the cooler under high heat load.4) Experimental Investigation on pulse tube refrigeration with He-H2 mixtureThe excellent heat transfer and flow characteristics of the hydrogen may contribute to a better performance of the PTC. Based on effect of He-Ha mixtures on the regenerator flow resistance, cold heat-exchanger performance, cooling capacity and efficiency (COP) at 3 OK with He-H2 mixtures is experimentally studied. The experimental results show, properly rationing He-H2 mixtures the cooling power and COP could be improved by several percent at a temperature near 30K. Besides, the effect of the He-Hi mixture on the performance of a two-stage pulse tube is also undertaken in order to reveal the operation mechanism of the gas mixture on the cooler. Experimental results in a two- stage pulse tube cooler show that the performance of the PTC could be greatly improved at 3 OK with He-Hj mixture and its positive effect is much larger than that of the single-stage cooler.5) PULSE TUBE NITROGEN LIQUEFIERA small-scale cryogenic liquid is widely used in a number of applications. A high-performance single-stage G-M pulse tube cooler was rebuilt into a nitrogen liquefier. The liquefaction rate, cool-down and warm-up characteristics of the liquefier operating under different modes were experimentally investigated.更多还原