热声制冷机的性能优化

研究了内热漏以及粘性不同逆损失对驻波声场热声制冷机性能的影响，导出了热声制冷机优化性能指标和参数的解析表达式。     

Construction and performance of a thermoacoustic refrigerator

This paper deals with the construction and performance of a thermoacoustic refrigerator. The manufacturing of the different components of the apparatus will be explained along with the reasons for using specific materials. The setup consists of three major parts: The refrigerator which is contained in a vacuum vessel, the electronic apparatus necessary for the measurements and acquisition of the experimental data, and the gas-control panel which is used to fill and purge the system and to prepare gas mixtures. The system is assembled and the first measurements show a good behavior. A low temperature of −65 °C is achieved which is one of the lowest reported temperatures up to date.     

微型热声制冷机的试验研究

研制了一种复合结构的PZT声驱动器,谐振管结构中加入了渐缩锥管后空管谐振试验的结果表明该驱动器所能产生的声压超过了目前已经报道的同频率范围的热声制冷机.在此基础上研制的微型热声制冷机在运行频率2.2 KHz时,平均压力从0.5 MPa到2.1 MPa之间进行了一系列的工况试验,得到了最大温降12.3 ℃,最大温差31 ℃,均达到同类机型目前报道的最佳性能.在此基础上提出了工程化应用的进一步改进方向.     

高频微型热声制冷机的样机设计与性能预测

介绍了高频微型热声制冷机的设计和性能分析,确定和部分优化了5 kHz压电喇叭驱动的热声实验样机的设计参数,为探索接近超声波频率的微型机工作的可能性,同时也对15 kHz微型热声制冷器进行了性能预测,并给出了主要参数,为高频微型热声制冷系统的实验研究提供了样机设计和性能预测.     

同轴行波热声制冷机性能实验

基于线性热声理论模型,设计了1台结构紧凑的同轴行波热声制冷机.采用行波热声发动机驱动,工作频率在57 Hz左右,以平均压力3.0 MPa的氦气为工作介质,固定制冷机入口压比为1.075的前提下,研究该制冷机的性能.通过改变惯性管内径,研究惯性管调相对制冷机性能的影响,制冷量随着惯性管内径的增大先增大后减小;研究Gedeon声流对制冷机性能的影响,该声流的存在极大地恶化了制冷机性能,使得制冷机在冷头0 ℃时,冷量下降11.4%,冷头-20℃时,下降47.66%,冷头温度越低影响越大.     

声学放大器对热声发动机性能的影响

对声学放大器的声功传输能力以及其对热声发动机性能的影响进行了实验研究,发现声学发大器只有在一定条件下才能提高热声发动机的输出压比,当末端阻抗减小时其放大能力也减小.声学放大器本身也是一个声学阻力部件,如果仅以负载引出功计算热声发动机的效率,声学放大器在输出端负载阻抗较大时能够提高系统热效率,当负载阻抗减小后,它将使发动机的热效率急剧降低.     

Experimental and simulation studies on the performance of standing wave thermoacoustic prime mover for pulse tube refrigerator

The thermoacoustic prime mover (TAPM) has gained considerable attention as a pressure wave generator to drive pulse tube refrigerator (PTR) due to no moving parts, reasonable efficiency, use of environmental friendly working fluids etc. To drive PTCs, lower frequencies (f) with larger pressure amplitudes (ΔP) are essential, which are affected by geometric and operating parameters of TAPM as well as working fluids. For driving PTRs, a twin standing wave TAPM is built and studied by using different working fluids such as helium, argon, nitrogen and their binary mixtures. Simulation results of DeltaEc are compared with experimental data wherever possible. DeltaEc predicts slightly increased resonance frequencies, but gives larger ΔP and lower temperature difference ΔT across stack. High mass number working fluid leads to lower frequency with larger ΔP, but higher ΔT. Studies indicate that the binary gas mixture of right composition with lower ΔT can be arrived at to drive TAPM of given geometry.     

Temperature difference generated in thermo-driven thermoacoustic refrigerator

The work proposes a simple and feasible calculation method--network model method to calculate temperature differences generated in thermo-driven thermoacoustic refrigerator (TAR). The theoretical calculation model is first built. The network model is given and used to make numerical calculations under different conditions including heat-pump stack positions in TAR, different oscillating pressure ratios (PR), plate spacings and different stack geometries. Theoretically calculated results show that the former two factors make significant influence on temperature differences, the influence of stack spacing on temperature difference has relation with PR, and cooling effect of pin-array stack is superior to that of parallel plate stack under other same conditions. Furthermore, theoretically calculated results and experimentally measured data are in good agreement at small acoustic pressure amplitude.     

压缩机选型对电冰箱实际使用性能的影响

通过分析压缩机制冷量对电冰箱运行的影响,阐述小冷量压缩机匹配电冰箱时在耗电量、最大热负荷等方面的优劣势。指出采用小冷量压缩机匹配大电冰箱时,必须在降低能耗的同时关注电冰箱在最大热负荷下储藏温度、压缩机工作系数等。     

Experimental and theoretical investigation on frequency characteristic of loudspeaker-driven thermoacoustic refrigerator

In this paper, the frequency characteristic of loudspeaker-driven thermoacoustic refrigerator (TAR) and the influence factors were investigated theoretically and experimentally. Experimental results under different conditions show that a narrow transmission frequency band of TAR exists to generate strong oscillation and cause significant thermoacoustic effect, and TAR achieves optimum performance at the resonance frequency. The frequency characteristic is determined by combined network elements of TAR. Then the analytical model was built to validate the experimental results. It provides a coupling method for design of loudspeaker-driven TAR system.     

Experimental study of a thermoacoustically-driven traveling wave thermoacoustic refrigerator

New configurations of traveling wave thermoacoustic refrigerators driven by a traveling wave thermoacoustic engine were introduced and tested in this paper. First, the performance of the refrigerator with different-diameter inertance tubes was investigated experimentally. Then, investigation of substituting a flexible membrane attached to inertial mass for inertance tube was tested. The experimental results show that the substitution could improve the efficiency of the system and lead to a larger cooling power. So far, using helium gas as the working gas, the system could provide 340 W cooling power at the temperature of −20 °C with working frequency of 57 Hz and average pressure of 3.0 MPa. The total COP, i.e., cooling power divided by heating power, is 0.16.     

Design and construction of a traveling wave thermoacoustic refrigerator

A traveling wave thermoacoustic refrigerator was designed, constructed, and tested. This refrigerator was composed of a linear motor, a branched tube, and a looped tube. A regenerator, composed of many screen meshes, was installed inside the looped tube. When the linear motor delivers an acoustic wave to the branched and looped tubes, heat pumping occurs along the regenerator. In this work, the regenerator radius and position were numerically optimized and the performance of the optimized refrigerator was measured. At the optimized values of regenerator radius and position, the refrigerator achieves a minimum cold temperature of 232 K and about 20% of the Carnot coefficient of performance at 265 K.     

高频热声制冷机中的压电喇叭特性

研究建立了1台5 kHz微型热声制冷实验样机,对压电喇叭谐振系统的阻抗特性,以及频率和电压响应特性进行了实验研究.初步的实验显示,压电喇叭与驱动电源和热声谐振系统之间需要在电学和声学上进行匹配,PZT5的压电陶瓷材料发热较大,且提供的声功率较小,这些是影响微型制冷的重要因素.     

Experimental investigation of a thermoacoustic refrigerator driven by a standing wave twin thermoacoustic prime mover

The objective of this study is to analyse the performance of thermoacoustic refrigerator (TAR) measured in terms of hot end temperature and temperature difference across refrigerator stack with two different spacing namely 0.4 mm and 0.8 mm and stack used in refrigerating section was made of low thermal conductivity materials namely Mylar sheet and photographic film & the experiments were carried out at 1 MPa pressure using helium as working fluid. High powered acoustic wave with frequency of 460 Hz and pressure amplitude of $?$0.07 MPa was obtained from twin thermoacoustic prime mover (TAPM) and this acoustic wave produced temperature difference of 16 °C across the Mylar sheet stack made of 0.4 mm spacing in refrigerator section. From this study, it has been inferred that twin TAPM can act as efficient drive for TAR.     

回热器参数对热声发动机性能影响的理论及实验研究

针对本实验室的行波热声发动机系统,研究了回热器对系统的重要作用.利用建立在线性热声理论基础上的模块化程序预测了不同回热器下系统的工作性能,并结合实验进一步分析比较了不同回热器对系统性能的影响.实验结果表明,低目数丝网填充的回热器更容易使系统起振,同时,起振温度随着工作压力的增加而降低;相同的输入功率和充气压力下,压比和加热块温度都随着目数的增大而升高;相同输入功率和目数下,压比和加热块温度随充气压力的增大而降低;丝网目数对系统频率的影响很小.     

Influence of working fluid on the performance of a standing-wave thermoacoustic prime mover

The thermoacoustic prime mover (TAPM) is an attractive alternative as a pressure wave generator to drive Pulse Tube Cryocoolers (PTCs), by the absence of moving parts, construction simplicity, reasonable efficiency, and environmental friendly. Decreasing the resonance frequency and improving the efficiency of the TAPM are important to drive the PTCs. These are controlled by the working gas parameters other than the dimensions of TAPM. In this technical note, the experimental studies carried out to evaluate the influence of different working fluids on the performances of a twin standing wave TAPM at various operating pressures have been compared with the simulation studies of the same system using DeltaEc wherever possible. The reasonably good agreement between them indicates the utility of DeltaEc for the optimal design of TAPM with the right working fluids for practical applications.     

Experimental investigation of thermal performance of random stack materials for use in standing wave thermoacoustic refrigerators

In a standing wave thermoacoustic refrigerator, heat transport from the “cold” to the “ambient” end of a stack is achieved by means of an oscillatory motion of a compressible fluid undergoing cyclic compression and expansion. However, the stacks can be both costly and impractical to fabricate due to material and assembly costs, which limits the cost benefits of thermoacoustic systems. Some of these problems could be solved by the application of stacks that have irregular geometries, for instance stacks made of “random” materials from metal machining (swarf), which are often considered as waste. In this paper, the thermal performance of stacks made of a few selected materials is determined by carrying out experiments in a standing wave thermoacoustic refrigerator. The reported results will be beneficial for developing low-cost thermoacoustic refrigerators or heat pumps for both domestic and commercial applications.     

几何参数对线性压缩机板弹簧性能的影响

在设计了11款不同基圆半径、厚度及涡旋槽偏心距的圆渐开线型板弹簧的基础上,利用ANSYS有限元分析软件,对上述板弹簧的刚度及应力特性进行了分析与比较,总结出了主要几何参数对板弹簧性能的影响.     

热声驱动的气-液双作用行波热声制冷机

提出了一种热声驱动的气-液双作用行波热声制冷机,对其性能进行了数值模拟分析.计算结果表明,在平均工作压力3.0 MPa,发动机定壁温加热温度440℃工况下,系统谐振频率为12.76 Hz,在-20℃制冷温度以及环境温度为27℃的情况下获得0.708 kW制冷量,整机的制冷系数(制冷量除以加热量)为0.512.在350℃、440℃以及550℃定壁温加热下,系统能够达到的最低制冷温度分别为-62.3℃、-68.3℃以及-70.8℃.系统整机相对卡诺效率在制冷温度变化范围内存在最大值.较低的发动机加热温度更有利于系统的热声转换,当发动机加热温度为350℃时,系统在-45℃制冷温度下达到25.30％最大相对卡诺效率.     

驻波热声制冷机分层回热器的特性研究

针对驻波制冷机回热器的7种分层方式进行研究,并通过DeltaEC计算驻波制冷机的声场分布、热流分布和相位差分布、最低制冷温度,以及制冷量与COP的特性规律。计算结果表明:随着制冷温度的降低,通过回热器的分层相应增大回热器的孔隙率,有利于改善流动损失,有效降低制冷温度,提高制冷效率。回热器的分层可以为热声制冷机性能的优化提供一种有效的手段。