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cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

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High Power Laser Science and Engineering 2016年第2期4卷 37-67页

作者： David C.Brown Sten Tornegrd Joseph Kolis Snake Creek Lasers LLC Clemson University Department of Chemistry

Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

关键词： cryogenic lasers high-average-power lasers high-peak-power lasers ultrafast lasers Yb lasers

Experimental Study on Cooling Down Process of a Nitrogen-Charged cryogenic Loop Heat Pipe

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Journal of Thermal Science 2023年第1期32卷 153-165页

作者： ZHAO Ya'nan YAN Tao LIANG Jingtao Key Laboratory of Space Energy Conversion Technology Technical Institute of Physics and ChemistryChinese Academyof SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

cryogenic loop heat pipes are highly efficient heat transfer devices at cryogenic temperature range,which have promising application prospects in satellites,spacecrafts,electronics,and so on.Cooling down process is a most critical process for a CLHP before startup.At present,secondary loop is a major way for a CLHP to fulfil cooling down and most studies are concentrated on heat transfer characteristics during normal operation.However,few investigations have been carried out on the cooling down process.In this paper,the cooling down process of a nitrogen-charged CLHP assisted with a secondary loop was experimentally investigated.A simple qualitative approach to estimate the cooling down time was proposed according to the law of conservation of energy.The two flow paths of the working fluid in the CLHP during the cooling down process were described.Experimental studies on the cooling down process with various secondary heat loads and working fluid inventory were presented in detail.With the increase of secondary heat load,the elapsed time of Stage III decreased significantly due to the larger mass flow rate in Path I.In addition,the effect of the working fluid inventory on the cooling down time was generally small in the range from 2.99 MPa to 3.80 MPa.However,with 2.80 MPa working fluid inventory,it required much longer cooling down time,which was because of the lack of liquid in the CLHP with low working fluid inventory.Moreover,the influence of gravity on the temperature variation of the components during the experiments was analyzed.This work is beneficial for better understanding of the cooling down process and optimizing of CLHPs.

关键词： cryogenic loop heat pipe secondary loop cooling down heat transfer

Testing Procedure for Laboratory Scale Semi cryogenic Combustion Chamber of LPRE with Problems Faced and Lessons Learned

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Journal of Thermal Science 2022年第6期31卷 2171-2177页

作者： KHAN Taj Wali QAMAR Ihtzaz Department of Aeronautics and Astronautics Institute of Space TechnologyIslamabad 44000Pakistan

Design, development, and testing of LPRE(Liquid Propellant Rocket Engine) are difficult and expensive tasks. Prior to full-scale design, it is indispensable to optimize important parameters at sub-scale. Propellants flow rates are low for a sub-scale or laboratory scale combustion chambers. It is hard to satisfy chamber cooling and chill feed lines quickly with low flow rates of propellants. This paper proposes a detailed procedure for testing of a laboratory scale semi-cryogenic combustion chamber. Many tests were conducted with a small scale adjustable length combustion chamber. The injection head of the chamber was interchangeable. Liquid-liquid pressure swirl injector and like impinging injectors were used with two different injection heads. Liquid oxygen and kerosene were used as oxidizer and fuel, respectively. Oxidizer to fuel mixing ratio was 0.29-0.45 and the total propellant mass flow rate was 0.06-0.1 kg/s. Problems were faced during testing, including, explosion in the combustion chamber, fuel injector blockage, unstable combustion, incomplete chilling and blockage of cooling water channel, etc. A detailed procedure is designed on the basis of the lessons learned which was experimentally proved.

关键词： LPRE cryogenic testing procedure combustion chamber

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

Enhanced tensile properties and wear resistance of additively manufactured CoCrFeMnNi high-entropy alloy at cryogenic temperature

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Rare Metals 2022年第4期41卷 1210-1216页

作者： Hong-Ge Li Peng-Cheng Che Xiao-Kun Yang Yong-Jiang Huang Zhi-Liang Ning Jian-Fei Sun Hong-Bo Fan School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Harbin-Electric Power Generation Equipment National Engineering Research Center Co. LtdHarbin 150028China

Here,bulk CoCrFeMnNi high-entropy alloy was prepared via laser melting deposition,and its microstructure and mechanical properties at room and cryogenic temperature were investigated by a series of microstructural character-izations and mechanical tests.The results showed that the as-built samples possessed a single fcc phase and highly dense microstructures.Compared to the mechanical prop-erties at room temperature,tensile properties,microhard-ness and wear resistance of the as-built samples showed a signiflcant enhancement at cryogenic temperature,which was attributed to the deformation mechanism converting from dislocation slipping to deformation twinning at cryogenic temperature.The formation of deformation nanotwins signiflcantly improved the deformation resis-tance in cryogenic conditions,and the sliding wear in the liquid nitrogen could decrease the oxygen concentration,suppress the generation of oxide particles and thus enhance the wear resistance.

关键词： wear cryogenic alloy

Operation of silicon-germanium heterojunction bipolar transistors with different structures at deep cryogenic temperature

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Science Bulletin 2019年第7期64卷 469-477页

作者： Guofang Yu Renrong Liang Xiawa Wang Jun Xu Tian-Ling Ren Institute of Microelectronics Tsinghua University Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University

In this work, the device performances of discrete and integrated SiGe heterojunction bipolar transistors(HBTs) with different device structures from 300 to 4.8 K were investigated. The turn-on voltages of baseemitter and base-collector junctions increased non-linearly with temperature cooled to 4.8 K. Energy bandgap engineering was taken into account for the analytical model of the turn-on voltage versus temperature. Incomplete ionization occurred in the base-collector junction because of the low doping concentration. The trap-assisted tunneling current in the forward base current was clearly observed below20 K. The ideality factor and saturation current were shown to be temperature dependence. The ideality factor was much larger than 2 below 40 K, indicating that the current is not only contributed by drift, diffusion and recombination, but also by tunneling. The peak current gain of the discrete SiGe HBTs achieved the maximum value of 3,388 at 80 K, while that of the integrated was 546 at 140 K. The transconductance in logarithm was linearly dependent on reciprocal temperature above 50 K, but flattened below 50 K.Early effect was evidently observed below 77 K in the fixed base current output characteristics of the discrete SiGe HBTs, and it was not obvious for the integrated SiGe HBTs.

关键词： SiGe HBTs Quantum computing cryogenic temperature Analytical model

Effect of deep cryogenic treatment on martensitic lath refinement and nano-twins formation of low carbon bearing steel

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Journal of Iron and Steel Research(International) 2020年第1期27卷 105-113页

作者： Xin-yang Lü Zhi-wei Wu Xiao He Jun Li Shao-hong Li Mao-sheng Yang Kun-yu Zhao Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunanChina Institute for Special Steels Central Iron and Steel Research InstituteBeijing 100081China

The effect of heat treatment and deep cryogenic treatment on microstructural evolution of low carbon martensitic bearing steel was investigated.The experimental results showed that the lath martensite was obtained by quenching and a few twins as substructures formed in some martensitic laths.The rudiment of sub-interfaces of martensitic lath was formed in the highdensity dislocation regions after deep cryogenic treatment;meanwhile,the number of twins increased,especially in the highdensity dislocation regions.This phenomenon is due to the increase in internal stress caused by cryogenic treatment.After tempering,the rudiment of sub-interface further evolved into the martensitic lath boundary,and thus the original martensitic laths were refined.The twins formed by cryogenic treatment did not disappear after tempering.In addition,small quantities of annealing twins formed in tempering process.Martensitic laths morphology and substructures in different stages of the heat and deep cryogenic treatment were observed by tninsmission electron microscopy.

关键词： Low carbon bearing steel-Deep cryogenic treatment Internal stress Sub-interface Nano-twin

Simulation and heat exchanger network designs for a novel single-column cryogenic air separation process

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Chinese Journal of Chemical Engineering 2019年第7期27卷 1498-1509页

作者： Quancong Zhang Zuqian Wu Zhikai Cao Qingyin Jiang Hua Zhou Department of Chemical and Biochemical Engineering National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters College of Chemistry & Chemical Engineering Xiamen University

To realize the industrialization of the novel single-column air separation process proposed in previous work,steady-state simulation for four different configurations of the single-column process with ternary(nitrogen,oxygen and argon)is developed.Then,exergy analysis of the single-column processes is also carried out and compared with the conventional double-column air separation process at the same capacity.Furthermore,based on the steady-state simulation of single-column processes,the different heat exchanger networks(HENs)for the main heat exchanger and subcooler in each process are designed.To obtain better performance for this novel process,optimization of process configuration and operation is investigated.The optimal condition and configuration for this process is consisted as:feedstock is divided into two streams and the reflux nitrogen is compressed at the approximate temperature of 301 K.In addition,HEN is optimized to minimize the utilities.HENs without utilities are obtained for the four different configurations of single-column process.Furthermore,capital costs of the HEN for different cases are estimated and compared.

关键词： cryogenic air separation Single-column Exergy Pinch technology Heat exchange network

Phenomenological modelling of flow behaviour of 20MnMoNi55 reactor pressure vessel steel at cryogenic temperature with different strain rates

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Defence Technology（防务技术） 2019年第3期15卷 326-337页

作者： Swagatam Paul Partha Dey Snehasish Bhattacharjee Sanjib Kumar Acharyya Prasanta Sahoo Jayanta Chattopadhyay Department of Mechanical Engineering Jadavpur University Kolkata India Department of Mechanical Engineering Academy of Technology Hooghly West Bengal India Bhaba Atomic Research Centre Mumbai India

In the present study a phenomenological constitutive model is developed to describe the flow behaviour of 20MnMoNi55 low carbon reactor pressure vessel (RPV) steel at sub-zero temperature under different strain rates. A set of uniaxial tensile tests is done with the variation of strain rates and temperature ranging from 10^-4s^-1 to 10^-1s^-1 and -80℃ to 140℃ respectively. From the experimental data, family of flow curves at different temperatures and strain rates are generated and fitted exponentially. The strain rate and temperature dependence of the coefficients of the exponential flow curves are extracted from these curves and characterised through a general phenomenological constitutive coupled equation. The coefficients of this coupled equation are optimised using genetic algorithm. Finite element simulation of tensile tests at different strain rates and temperatures are done using this coupled equation in material model of Abaqus FEA software and validated with experimental results. The novelties of proposed model are:(a) it can predict precisely the flow behaviour of tensile tests (b) it is a simple form of equation where fitting parameters are both function of strain rate ratio and temperature ratio,(c) it has ability to characterize flow behaviour with decreasing subzero temperatures and increasing strain rates.

关键词： Flow behaviour RPV steel cryogenic temperature Strain rate