【作者】 范兵；

【导师】 胡大鹏；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2009， 硕士

【摘要】 全球对能源的消费中,天然气将成为需求增长最快的能源,而在天然气加工工艺中需要能在高压下操作且高效的气体膨胀制冷设备。静止式气波制冷机是一种新型气体膨胀制冷设备,其工作原理为:利用自激励射流振荡器生成的振荡射流对一端封闭的接受管进行周期性射气,入射气把其能量通过激波的运动传递给接受管内原有气体并通过接受管壁向环境散热实现“冷却”。静止式气波制冷机无任何转动部件、只需要简单的静密封,且具有很强的带液工作能力,因此特别适合用于加工处理高压天然气。目前,静止式气波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.2006AA05Z216),通过数值模拟和实验对多管静止式气波制冷机的性能进行研究。附壁射流的特性如偏转程度、附壁距离等是静止式气波制冷机设计的基础。本文首先对附壁射流的特性作了数值模拟,分析了附壁射流的流场,考察了附壁元件结构参数和操作参数对附壁特性的影响。研究表明射流的偏转特性主要与射流两旁的压差有关,侧壁直壁段对射流的附壁点具有很好的引导作用。接受管是制冷实现的场所,本文研究了接受管中波系的运动与传播过程。得出入射波扫过以后,管内气体的压力、密度、温度等有一个突跃升高。波在传播的过程中由于摩擦等原因强度会降低;在波到达之前,接受管中的气体正朝着管口的方向运动,处于排气的过程,但是在波和入射气体的共同作用下,在波面处,速度大小急剧下降,然后变成跟入射气流方向一致。多管静止式气波制冷机相比双管式更具有工业应用价值,故本文在对双管射流振荡器和接受管研究的基础上,开发了适合多管静止式气波制冷机需要的射流振荡器,将改造的音波和正反馈振荡器用于多管静止式气波制冷机,对振荡器的可振性、振荡频率以及它们的影响因素作了数值模拟研究,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:在对多管静止式气波制冷机数值模拟的基础上对其进行了设计和加工,并对它进行了实验研究。结果表明,提高气波制冷机的入口压力,可以增大出口气体的温降,入口温度的提高也会导致温降的增大。高频情况下的正反馈振荡器作为振荡源,射流对接受管内气体的做功频率较高,相对于较低频率的音波振荡器,可以得到更高的温降。更多还原

【Abstract】 Natural gas will become the fastest-growing demand energy of the global energy consumption.High-performance expansion refrigeration equipments suited for operating condition of high pressure are needed urgently for natural gas’ expansion refrigeration technology.The static gas wave refrigerator is a new type of expansion refrigerator,in which the self-induced jet oscillator is used to generate oscillation jet’s periodical injection into receiving tubes with one-closed end.In the receiving tube,gas waves are produced owing to the interaction between the driving gas and the driven gas.Energy is rapidly transferred from the driving gas to the driven gas by means of propagation of the gas waves,which result in temperature increase of the latter and then heat dissipates to environment across the tube wall. Static gas wave refrigerator has no moving parts and its seal is simple.Hence,its use is not confined by the condition of high pressure.However,the refrigeration efficiency of the jet-oscillation refrigerator is at a low level presently,and it could not satisfy the requirement of natural gas’s industrial production.Performance and mechanism of the multiple static gas wave refrigerator 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 self-induced jet oscillator is a key component of static gas wave refrigerator and it is developed on the basis of jet’s wall-attaching effect which is also called Coanda effect.Firstly, this paper numerically simulates the properties of wall-attaching jet and analyses the flow field of wall-attaching jet.Effects of the element’s geometrical sizes and operating conditions are simulated numerically,and emphasis is placed on analysis of geometrical properties and pressure distribution properties together with their relationship.It is concluded that the deflection characteristics of the jet flow is associated with the pressure on both sides of the jet. Component geometry and operating conditions will affect the pressure distribution of the jet on both sides,and the straight wall has an optimum value for the jet’s wall-attachment.The receiving tube is the place of refrigeration.The gas and wave’s motion and propagation in the receiving tube are studied.As the wave sweeps,the pressure,density and temperature of the gas rise rapidly.After the incident,wave will be reduced because of friction in the process of dissemination.Before the arrival of the wave,the gas in the receiving tube is moving towards the open end direction,and it is in the phase of exhausting.Under the action of the waves and injecting gas,the velocity of the gas decreases suddenly,and then turns to the direction of the injecting gas.The application shows that the multi-tube gas wave refrigerator is more effective than the double-tube gas wave refrigerator.The jet-oscillation refrigerator works on the basis of the jet oscillator.The frequency modulation of the jet’s oscillation and decreas of total pressure loss of the jet passing the oscillator are important approach to improve the performance of the refrigerator.Therefore this paper develops the jet oscillator for multi-static gas wave refrigerator based on the study of jet oscillator and the receiving tube,transforms the sonic oscillator and feedback oscillator for multi-static gas wave refrigerator.This paper numerically simulates the oscillation availability and frequency of the static gas wave refrigeration.As a conclusion,the jet oscillates only in a certain range of geometrical sizes and operating conditions.This paper does experiments on the multi-static gas wave refrigerator based on the numerical simulation and studys the effects of the element’s geometrical sizes and operating conditions.In conclusion,matching the other parameters,as the inlet pressure rises,the temperature drop also rises.The temperature drop also rises as the inlet temperature rises.Matching with the oscillation frequency,the length of the receiving tube,diameter of the nozzle and the pressure ratio,there is a best injecting frequency.If the gas is generted by a high frequency oscillator-a feedback oscillator,as the frequency to drive the gas in the receiving tube is also high,so higher temperature drop can be realized as to the sonic oscillator.更多还原