低起振温差的热声热机特性研究

发布时间：2018-01-10 23:22

本文关键词：低起振温差的热声热机特性研究　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：热声技术是一种利用热声效应实现热能与声能(一种机械能量)转换的新技术,在低品位能源尤其是新能源和低温余热的利用方面有很大的应用前景。热声热机起振温度的高低直接关系到系统可利用能量的品位,因此,研究低温差的热声热机对于低品位能源的利用具有十分重要的意义。为了探索低起振温度和高性能热声热机系统的特性,本文开展了低温差热声热机系统的数值模拟研究,主要研究内容如下:1)利用DeltaEC软件,同时考虑系统效率与高温换热器加热温度,设计了低温差的驻波热声热机,并利用二端口网络模型及起振判据模拟分析了驻波热机的起振特性,研究了板叠和谐振管结构参数对热声热机稳态和起振特性的影响。研究结果表明:在不同的充气压力下,存在最优的板叠间距,使起振温度最低,而最优板叠间距与热渗透率的比值基本不变,对于所研究的驻波热声热机,该比值大约为2.25。2)运用热声理论和传输矩阵方法推导了多级环形热声热机的起振条件式,该起振条件式是系统的结构配置、工况和工质热物性质的隐式函数,可以为热声热机的设计优化与性能分析提供一种工程实用的网络方法。将该网络方法用于多级环形热声热机的研究,模拟分析了起振特性及其影响因素。研究表明:在不同充气压力下,均存在获得最低起振温差的最优回热器丝网水力半径;热机的级数越多,起振温差和振荡频率越低。同时,利用DeltaEC软件对热机的稳态特性也进行模拟分析,计算了热声热机的输出声功和效率。研究结果表明:在相同的加热功率下,采用混合工质可以降低回热器两端所需的温差,并产生较大的声功率。3)运用推导的起振条件式,对多级环形热声热机驱动的制冷系统进行了起振特性及影响因素的研究;同时,分析了稳定工况下的系统特性,以及制冷温度和热机加热温度对系统性能的影响。研究结果显示:小型热声热机驱动的制冷系统有较低的起振温差;相对于制冷温度,制冷机单元的相对卡诺性能系数存在最大值,且热机的加热温度越高,该最大值也越大,对应的制冷温度越低。
[Abstract]:Thermoacoustic technology is a new technology which uses thermoacoustic effect to realize the conversion of heat energy to sound energy (a kind of mechanical energy). It has great application prospect in low grade energy, especially in the utilization of new energy and low temperature waste heat. The starting temperature of thermoacoustic engine is directly related to the available energy grade of the system. It is very important to study the thermoacoustic engine with low temperature difference for the utilization of low grade energy. In order to explore the characteristics of low starting temperature and high performance thermoacoustic heat engine system. In this paper, the numerical simulation of low temperature differential thermoacoustic engine system is carried out. The main research contents are as follows: 1) using DeltaEC software, considering system efficiency and heating temperature of high temperature heat exchanger. The standing wave thermoacoustic engine with low temperature difference is designed, and the characteristics of the standing wave thermoacoustic engine are simulated and analyzed by using the two-port network model and the starting criterion. The influence of the structural parameters of laminated and resonant tubes on the steady state and vibration initiation characteristics of thermoacoustic thermoengine is studied. The results show that the optimal stack spacing exists under different inflatable pressures, so that the starting temperature is the lowest. However, the ratio of optimal plate spacing to thermal permeability is almost unchanged, for the standing wave thermoacoustic engine studied. Based on thermoacoustic theory and transfer matrix method, the starting condition of multistage ring thermoacoustic engine is derived, which is the configuration of the system structure. The implicit function of the working condition and the thermal properties of the working fluid can provide an engineering practical network method for the design optimization and performance analysis of the thermoacoustic engine. The network method is applied to the study of the multistage ring thermoacoustic engine. The characteristics of starting vibration and its influencing factors are simulated and analyzed. The results show that under different inflatable pressures, there is an optimal hydraulic radius of the regenerator wire mesh to obtain the lowest starting temperature difference. The more series of heat engine, the lower the temperature difference and frequency. At the same time, the steady state characteristic of heat engine is simulated and analyzed by DeltaEC software. The output acoustic work and efficiency of the thermoacoustic engine are calculated. The results show that under the same heating power, the temperature difference between the two ends of the regenerator can be reduced by using the mixed working fluid. The vibration initiation characteristics and influencing factors of the refrigeration system driven by multi-stage ring thermoacoustic engine are studied by using the derived starting conditions. At the same time, the characteristics of the system under steady working conditions and the effects of refrigeration temperature and heating temperature on the performance of the system are analyzed. The results show that the temperature difference of starting vibration of the refrigeration system driven by a small thermoacoustic engine is lower; Compared with the refrigeration temperature, the relative Carnot performance coefficient of the refrigerator unit has the maximum value, and the higher the heating temperature of the heat engine, the larger the maximum value, and the lower the corresponding refrigeration temperature.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK05

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