【作者】 杨军；

【导师】 胡大鹏；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2008， 硕士

【摘要】 天然气深冷加工工艺迫切需要能在高压下操作且高效的气体膨胀制冷设备。射流振荡气波制冷机是一种新型气体膨胀制冷机,其工作原理为:利用双稳射流振荡器生成的振荡射流来形成对一端封闭的接受管的周期性入射,入射气因其能量通过载能气波的运动传递给接受管内原有气体并经接受管壁向环境散发损失而“冷却”。射流振荡制冷机无任何转动部件、只需简单静密封,因此特别适合用于高压天然气的加工处理。目前,射流振荡制冷机的研究还很不成熟,其性能参数(主要为等熵效率)离天然气工业生产的要求尚有一定的差距。本文结合国家863高技术项目“天然气压力能综合利用新技术研究”(No.2006AA052216)将正反馈射流振荡器引入射流振荡气波制冷机中,从实验和气体动力学数值分析两方面对正反馈式射流振荡气波制冷机的运行性能开展研究。射流振荡器是射流振荡制冷机的关键部件,它是在射流的附壁效应(也称Coanda效应)基础上开发出来的。振荡器内射流的稳定振荡是射流振荡制冷机工作的前提条件,其振荡频率的调制和总压损失的控制是改善制冷机性能的重要途径。本文首先对正反馈射流振荡器的振荡特性作了研究,通过数值模拟对正反馈射流的振荡波形和内部流场进行分析,考察了元件几何尺寸和操作条件以及介质物性的影响,重点研究了这几种因素对振荡频率和可振性的影响。射流的振荡特性如振荡频率、振荡压比是射流振荡器设计的基础性数据,也是影响射流振荡器和接受管耦合的主要因素,决定制冷效率。本文将跨音速正反馈射流振荡器与接受管耦合,对耦合后的射流振荡气波制冷机的可振性、振荡频率以及它们的影响因素作了实验研究,得出如下结论:射流只在一定的操作条件和几何结构尺寸范围内才能稳定振荡;射流的振荡频率在较高压比下只受反馈管长和反馈管容腔大小的显著影响,在小压比下随压比的增大而增加;其它结构尺寸和操作条件只影响可振性。多管式射流振荡气波制冷机相比双管式更具有工业应用价值,故本文对正反馈式多管射流振荡气波制冷机进行了数值模拟分析。计算了多种排气口形式的排气效果和相应的卷吸现象。重点分析了反馈管容腔对射流切换时间的影响,得到结论:反馈管容腔增大,射流切换时间增长,有利于射流均匀射入每个接受管,提高整体制冷效率。本文将正反馈射流振荡器引入射流振荡气波制冷机,依据其振荡特性,得到频率高,可振范围宽的元件结构。将气波机的可运行范围扩大,为寻找最佳耦合点,提高其制冷效率奠定了基础。更多还原

【Abstract】 High-performance expansion refrigeration equipment suited for operating condition of high pressure is needed urgently for natural gas’ expansion refrigeration technology. Jet-oscillation refrigerator is a new type of expansion refrigerator, in which self-induced jet oscillator is used to generate oscillation jet’s periodical injection into receiving tube with one-closed end. In the oscillation tube, gas waves are produced owing to interaction between the injected gas and the intrinsic gas. Energy is rapidly transferred from the injected gas to the intrinsic gas by means of propagation of those gas waves, which results in temperature increase of the latter and then heat dissipation to environment across the tube wall. The refrigeration of the injected gas is obtained due to its energy loss. The jet-oscillation refrigerator has no moving part and its seal is simple. Hence, its use is not confined under the condition of high pressure. Yet, the refrigeration efficiency of the jet-oscillation refrigerator is at a low level presently, and could not satisfy requirement of natural gas’s industrial production. In this paper, the feedback fluidic device is introduced to jet-oscillation refrigerator for the high frequency performance. The performance and mechanism of the jet-oscillation refrigerator with feedback fluidic device are investigated in the current paper supported by Chinese 863 National Program Foundation "Study on new technology of combined utilization of natural gas’s pressure energy "(No.2006AA05Z216).The bistable fluidic device is a key component of jet-oscillation refrigerator and it is developed on the basis of jet’s wall-attaching effect which is also called Coanda effect. The frequency modulation of the jet’s oscillation and decrease of total pressure loss of the jet passing the oscillator are important approach to improve the performance of the refrigerator. This paper studies the oscillation performance of jet in feedback device. First of all, the waveforms and internal flow field of the oscillation in feedback fluidic device are studies through the numerical simulation. The influence of geometrical size and operating condition also the media physical property on the performance of feedback device is investigated. The study emphasize on the variation of frequency and ratio of oscillation-available pressure with the geometrical size. Other factors determine the availability and stability of oscillation.The oscillation performance of jet, as oscillation frequency, is the essential data for designing the fluidic device, which is also the key factor that influence the coupling effect of fluidic device and receiving tube. This paper does experiment on the oscillation availability and frequency of feedback jet-oscillation gas wave refrigeration. As a conclusion, the jet oscillates only in a certain range of geometrical sizes and operating conditions. Under the condition of high pressure ratio, the frequency of the jet’s oscillation is only affected by the feedback tube’s length and chamber remarkably. Under the condition of low pressure ratio, the frequency descends with rise of the pressure ratio. The influence of outlet port clearance is explored. The change of receiving tube length mainly results in the variation of the highest oscillation-availability ratio of pressure and tube response.The field application showed that the multi-tube gas wave refrigerator is more effective than the double-tube. This paper also studies on the performance of multi-tube through numerical simulation emphasizing on the switching time. This paper draws a conclusion that the switching time grows with the increasing of feedback tube chamber. This law is favorable to improve the refrigeration efficiency.This paper introduces positive feedback to Jet-oscillation refrigerator and high frequency and a wide range of oscillation are obtained based on the oscillation property. This method widens the operation range of jet-oscillation refrigerator and lays a foundation for finding the optimal couple point and improving the refrigeration efficiency.更多还原