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1.
The paper provides some results concerning the numerical study of the strongly transient gasdynamic processes in a pressure-wave
refrigerator (PWR). A hierarchical set of numerical models from the simplest one-dimensional to a fully three-dimensional
formulation is introduced. The computations show that one-dimensional solutions give a reasonable foundation for the understanding
of PWR operational principles but cannot satisfactorily predict the refrigeration efficiency. Good agreement with experiment
is achieved by considering two- and three-dimensional effects of gas mixing by overlap of rotating nozzles and expansion tubes.
Received
Received 14 February 1996 / Accepted 1 June 1996 相似文献
2.
Thermoacoustic refrigeration is an emerging cooling technology which does not rely for in its operation on the use of any moving parts or harmful refrigerants. This technology uses acoustic waves to pump heat across a temperature gradient. The temperature gradient forms across the ends of a porous body, called the stack, enclosed in a resonator. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this paper, the design, construction, operation, and modeling of a piezo-driven thermoacoustic refrigerator are detailed. The performance of the refrigerator is significantly enhanced by coupling the acoustic driver with an elastic structure, referred to as a dynamic magnifier. Proper selection of the magnifier parameters can increase the magnitude of the pressure oscillations across the stack, and consequently the temperature difference. The magnified refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across a 10 °C temperature difference with an input power of 7 W. All the theoretical predictions are validated against data from experimental prototypes. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of piezo-driven thermoacoustic refrigerator configurations. 相似文献
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在高温超导磁体试验装置设计中,冷却方式有制冷机传导冷却和液氮浸泡冷却两种。制冷机传导冷却是将磁体通过一种热导率高的材料与制冷机冷头相连。该方式为保证绝缘、冷量传递、温场均匀性等指标,对磁体的结构设计要求较高;液氮浸泡冷却是将高温超导磁体浸泡在液氮中,该方式虽然对磁体结构设计要求有所降低,但在试验过程中需定期补充蒸发掉的液氮,试验过程较繁琐。有鉴于此,我们设计了一套利用热虹吸原理的零蒸发液氮浸泡冷却高温超导磁体试验装置,超导磁体吊装在杜瓦上盖板法兰下,液氮浸泡超导磁体,带GM制冷机的液氮再冷凝杜瓦与超导磁体分开,用一根真空绝热管道将两者连接起来,利用热虹吸原理构成自循环系统。 相似文献
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A simplified physical model for calculating the onset temperature ratio and the frequency of a standing wave thermoacoustic engine (SWTE) in the time domain is built based on thermodynamic analysis. Coefficients of transient pressure drop and heat transfer are first deduced from linear thermoacoustic theory. By numerical computation, the evolutions of the pressure amplitude and the spectrum characteristics during the onset process are presented. Furthermore, the effects of stack spacing, charge pressure, and resonator length on the onset temperature ratio and the frequency are calculated. Relatively good agreement between the computational and the experimental results has been achieved, which validates the model for calculating the onset characteristics. 相似文献
7.
We study the local stability near the maximum figure of merit for the low-dissipation cyclic refrigerator,where the irreversible dissipation occurs not only in the thermal contacts but also the adiabatic strokes.We find that the bounds of the coefficient of performance at a maximum figure of merit or maximum cooling rate in the presence of internal dissipation are identical to those in the corresponding absence of internal dissipation.Using two different scenarios,we prove the existence of a single stable steady state for the refrigerator,and clarify the role of internal dissipation on the stability of the thermodynamic steady state,showing that the speed of system evolution to the steady state decreases due to internal dissipation. 相似文献
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