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Temperature Difference and Stack Plate Spacing Effects on Thermodynamic Performances of standing-wave Thermoacoustic Engines Driven by Cryogenic Liquids and Waste Heat

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Journal of Thermal Science 2022年第5期31卷 1434-1451页

作者： GUO Lixian ZHAO Dan BECKER Sid Department of Mechanical Engineering College of EngineeringUniversity of CanterburyPrivate Bag 4800Christchurch8041New Zealand

The standing-wave thermoacoustic engines(TAE)are applied in practice to convert thermal power into acoustic one to generate electricity or to drive cooling devices.Although there is a number of existing numerical researches that provides a design tool for predicting standing-wave TAE performances,few existing works that compare TAE driven by cryogenic liquids and waste heat,and optimize its performance by varying the stack plate spacing.This present work is primarily concerned with the numerical investigation of the performance of TAEs driven by cryogenic liquids and waste heat.For this,three-dimensional(3-D)standing-wave TAE models are developed.Mesh-and time-independence studies are conducted first.Model validations are then performed by comparing with the numerical results available in the literature.The validated model is then applied to simulate the standing-wave TAEs driven by the cryogenic liquids and the waste heat,as the temperature gradientΔT is varied.It is found that limit cycle oscillations in both systems are successfully generated and the oscillations amplitude is increased with increasedΔT.Nonlinearity is identified with acoustic streaming and the flow reversal occurring through the stack.Comparison studied are then conducted between the cryogenic liquid-driven TAE and that driven by waste heat in the presence of the same temperature gradientΔT.It is shown that the limit cycle frequency of the cryogenic liquid system is 4.72%smaller and the critical temperatureΔT_(cri)=131 K is lower than that of the waste heat system(ΔT_(cri)=187 K).Furthermore,the acoustic power is increased by 31%and the energy conversion efficiency is found to increase by 0.42%.Finally,optimization studies on the stack plate spacing are conducted in TAE system driven by cryogenic liquids.It is found that the limit cycle oscillation frequency is increased with the decreased ratio between the stack plate spacing and the heat penetration depth.When the ratio is set to between 2 and 3,the overall performance of the cryogenic liqui

关键词： thermoacoustic engine standing-wave cryogenic thermodynamics acoustical energy plate spacing heat transfer acoustic streaming

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Experimental study of large-amplitude standing-wave field obtained in a standing-wave tube with uniform cross section

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Chinese Journal of Acoustics 2019年第3期38卷 353-368页

作者： MIN Qi HE Wanquan WANG Quanbiao GE Shuping WANG Shengyu Honghe University

A large-amplitude standing-wave field of 182.1 dB is obtained under the excitation at the resonant frequency of the lst-order peak of the sound pressure transfer function in an improved standing-wave tube experimental system,and saturation of harmonics and waveform distortion are investigated experimentally for the large-amplitude standing-wave fields obtained under the excitations at the resonant frequencies of the 1 st-to the 5 th-order peaks.The results show that although the sound pressure level has reached 182.1 dB under the excitation at the resonant frequency of the 1 st-order peak,the waveform distortion is the minimum and the harmonic saturation is not observed.However,the large-amplitude standing-wave field excited at the resonant frequency of the 3 rd-order peak exhibits the trend of the harmonic saturation.Comparison of the large-amplitude standing-wave fields obtained under the excitations at valley resonant frequencies shows that the standing-wave field excited at the resonant frequency of the 1 st-order valley has the largest SPL,but also has the largest waveform distortion.Under the same source-driving voltage,the standing-wave field excited at the resonant frequency of the 1 st-order peak always has greater SPL than the standing-wave field excited at the resonant frequency of the 1 st-order valley.Hence,to obtain a large-amplitude standing-wave field,it’s better to excite at the resonant frequency of the 1 st-order peak of the SPTF by using loudspeaker in a standing-wave tube with uniform cross section.

关键词： domain SPL Experimental study of large-amplitude standing-wave field obtained in a standing-wave tube with uniform cross section

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Development　of　Compact　standing－wave　Guides　with　on－Axis　Coupler　of　Electron　Linac　for　Medical　Radio

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Tsinghua Science and Technology 1996年第1期1卷 70-76页

作者：林郁正童德春杨越靳清秀孙翔孙敬清胡少光陈怀璧黄海陈秉彝张益林李跃增孙宝玉胡文胜邹阳 Department of Engineering Physics Tsinghua University Beijing 100084 Beijing Institute of Electronics & Vacuum Technology Beijing 100016

A series of completely sealed standing-wave (SW) accelerator guides was developed and installed on 3,4, 6, 9 and 14 MeV home-made electron linacs for medical and industrial uses. In the development of these SW guides, various subjects, including particle dynamics, microwave properties etc, were studied. The fsctors influencing the transverse motion were considered analytically and using a simulation code, TRSV. The problem of electron backbombardment in SW linac was analyzed by a 3-dimensional trace code, SB. Simultaneously decreasing the length of the first cavity and the injection voltage can reduced the electron backbombarding power. The code PPDW based on equivalent circuit theory was developed to analyze many microwave characteristics of arbitrarily composed coupled cavity chains. This research contributed to the successful development of the 3, 4, 6, 9 and 14MeV SW accelerator guides. For example, in the recently developed 14MeV SW guide, the beam passes smoothly through a 1.45 m long guide with a beamhole (diameter of 7 mm) without using a focusing solenoid.

关键词： standing-wave accelerator guide electron linac medical and industrial uses particle dynamics simulation electron backbombardment microwave properties

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Phase grating in a doubly degenerate four-level system

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Chinese Physics B 2013年第10期22卷 287-291页

作者：刘云王朴彭双艳 College of Physics Science and Technology Bijie University

In this paper, we suggest a doubly degenerate four-level system, in which the transition takes place between the hyperfine energy 52S1/2 F = 1 and 52P3/2 F = 2 in rubidium 87 D2 line, for studying atomic phase grating based on the cross-Kerr and phase conjugation effects. The phase grating with high efficiency can be obtained by tuning phase shift Ф between the coupling and probe field, when the coupling intensity is much stronger than the strength of probe field. Under different coupling intensities, a high diffraction efficiency can be maintained. A new and simple way of implementing phase grating is presented. However, in such an atomic system, two main limitations must be taken into account. First, the independence between steady state probe susceptibility and the coupling intensity, when the population decay rate is larger than the Rabi frequency of the coupling field, cannot result in diffraction grating; second, the sample to be prepared should not be too long.

关键词： phase grating quantum interference four-level system standing-wave

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SHAPED DUAL-REFLECTOR ANTENNA WITH RING FOCUS

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Science China Mathematics 1991年第10期34卷 1243-1255页

作者：章日荣杜树祥王汉礼周康健王涛 Institute No.54 Ministry of Machinery & Electronics Industry Shijiazhuang 050002 PRC

The equations of the reflector contours and the radiation patterns of the shaped dual-reflector antenna have been derived, and the methods of designing the antenna are also intro-duced briefly. The calculated and measured results suggest that this new type of antennahas the advantages of low VSWR (voltage standing-wave ratio), low sidelobe, and high gain.Therefore it opens a bright prospect for the improvement of mid-and small-aperture anten-na performance, and gives the possibility for the realization of the 1990s new standard spec-ified by CCIR (International Radio Consultative Committee) on mid-and small-aperture an-tenna for satellite-communication earth stations.

关键词： low VSWR (voltage standing-wave ratio) low sidelobe high gain mid- and small-aperture reflector antenna with ring focus.

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