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空分系统压缩余热自利用方法的比较研究

工程热物理学报 2024年第2期45卷 343-350页

作者：甘浩然方松张涵玮王凯植晓琴邱利民浙江大学制冷与低温研究所杭州310027 浙江省制冷与低温技术重点实验室杭州310027

利用热驱动制冷循环回收压缩余热,将制取冷量用于冷却各级空压机入口空气,从而实现压缩余热“自利用”,是降低空压机组能耗,促进空分装备低耗化的有效途径之一。本文主要构建了基于有机朗肯–蒸气压缩制冷的空压流程(ORVC-ACS)和基于吸... 详细信息

利用热驱动制冷循环回收压缩余热,将制取冷量用于冷却各级空压机入口空气,从而实现压缩余热“自利用”,是降低空压机组能耗,促进空分装备低耗化的有效途径之一。本文主要构建了基于有机朗肯–蒸气压缩制冷的空压流程(ORVC-ACS)和基于吸收式制冷的空压流程(ARS-ACS)的热力学模型,对比分析了环境温、湿度和冷冻水出口温度对两种压缩余热自利用系统的性能影响。结果显示,当气候条件发生波动时,采用ORVC回收压缩余热可产生更高的节能效益,节能率可达3.5%,而ARS-ACS的节能率仅为2.6%。此外,高冷冻水输送温度更有利于ORVC-ACS的节能效果,六万等级空分系统的节能量最高可达854 k W。

关键词：低温空分系统压缩余热回收有机朗肯–蒸气压缩吸收式制冷

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两级GM制冷机数值模拟与分析

低温工程 2024年第3期 20-27页

作者：陈鑫植晓琴韦涛高天邱利民浙江大学制冷与低温研究所杭州310027

采用Sage软件建立了两级GM制冷机整机数值模型,并通过实验结果进行了验证。基于数值模型和?分析方法,分析了不同制冷温度下压缩机、旋转阀与冷头的损失分布。结果表明,损失主要发生在压缩机和旋转阀上。冷头的损失随着制冷温度的降低而... 详细信息

采用Sage软件建立了两级GM制冷机整机数值模型,并通过实验结果进行了验证。基于数值模型和?分析方法,分析了不同制冷温度下压缩机、旋转阀与冷头的损失分布。结果表明,损失主要发生在压缩机和旋转阀上。冷头的损失随着制冷温度的降低而增加,在4.2 K时36%的损失发生在冷头上,其中61%的冷头损失是由于实际气体效应引起。压缩机、旋转阀和回热器的低效性以及实际气体效应主导了制冷机的损失,导致制冷机效率低下。

关键词： GM制冷机数值模拟 ?分析液氦温区

Exhaust process of cryogenic nitrogen gas from a cryogenic wind tunnel with an inclined exit

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第5期24卷 419-431页

作者： Jingfeng LI Kai WANG Chenjie GU limin qiu Institute of Refrigeration and Cryogenics Zhejiang UniversityHangzhou 310027China Baima Lake Laboratory Hangzhou 310051China

A new structural design for the vent stack with an inclined exit was proposed to reduce the settlement hazard of the cryogenic plume from a cryogenic wind tunnel;it extends the plume trajectory to increase the effective contact space and time for mixing between the plume gas and atmospheric air before the plume settles to the ground,contributing to more efficient energy consumption for ***-scale experiments and numerical simulations of plume dispersion based on vertical and 30°-and 45°-inclined exits were conducted to study harm reduction and energy-saving *** of the minimum temperature and minimum oxygen concentration of the plume near the ground indicate that the new exhaust design with an inclined exit clearly reduces the settlement *** windless conditions and without using a fan-ejector system,up to 15.9%of the heating energy used by the burner can be saved by adopting the new design.

关键词： Cryogenic gas dispersion Cryogenic wind tunnel Exhaust method Hazard reduction Inclined exit

Prospects of sea launches for Chinese cryogenic liquid-fueled medium-lift launch vehicles

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Chinese Journal of Aeronautics 2021年第1期34卷 424-437页

作者： Zhengyu SONG Zhifeng XIE limin qiu Dalin XIANG Jinglin LI China Academy of Launch Vehicle Technology Beijing 100076China Beijing Institute of Astronautical Systems Engineering Beijing 100076China College of Energy Engineering Zhejiang UniversityHangzhou 310027China

This paper introduces the sea-launch technology of a cryogenic liquid-fueled medium-lift *** first reviews the current state of sea launch technology,and then gives a brief introduction of China’s New Generation Medium-lift Launch Vehicle(NGMLV).The innovations in the NGMVL,such as responsive test and launch control,a H3 launch model,and unmanned operations,provide convenience for sea *** on these innovations,this paper proposes a sea launch scheme,including the system configuration,test and launch processes,and an improved adaptive design for the ***,the launch platform is discussed in detail,which integrates the functions of sea transportation,assembly and test,as well as technical and launch *** layout and function divisions,fluid filling,gas supply and distribution systems,and lossless storage technology of LH2 are described in *** breakthrough in sea launch technology will enable China to launch medium and large satellites and constellations‘both on land and sea’,especially into low-inclination Low-Earth Orbits(LEOs),and it allows China to remain competitive in the fast-paced space industry.

关键词： Autonomous operations Launch platform Launch vehicles Liquid hydrogen storage Sea launches

低温流体在不同倾角填料表面的气液逆流特性理论研究

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低温工程 2024年第3期 1-7,55页

作者：詹高铭植晓琴滕艺璇周华彬邱利民浙江大学制冷与低温研究所杭州310027

采用CFD方法,建立规整填料局部逆流模型,通过分析流动形态、润湿率、持液率等参数,研究了低温氮氧在45°和60°倾角填料气体逆流对流动特性的影响。结果表明,逆流气体对常温水的润湿性有促进作用,对低温工质产生负面影响。对于低温流体... 详细信息

采用CFD方法,建立规整填料局部逆流模型,通过分析流动形态、润湿率、持液率等参数,研究了低温氮氧在45°和60°倾角填料气体逆流对流动特性的影响。结果表明,逆流气体对常温水的润湿性有促进作用,对低温工质产生负面影响。对于低温流体,45°填料能提供高于86%的润湿面积,逆流气体影响下润湿率降低6.90%,而60°填料润湿率仅降低0.40%,但其润湿率仅约67%。60°填料的压降低于50 Pa/m,远低于45°填料,能有效降低压降损失,更适合用于大处理量的空分精馏过程。

关键词：低温精馏规整填料气液逆流数值模拟

Modeling cavitation flow of cryogenic fluids with thermodynamic phase-change theory

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Chinese Science Bulletin 2013年第4期58卷 567-574页

作者： ZHANG XiaoBin WU Zhao XIANG ShiJun qiu limin Institute of Refrigeration and Cryogenic Engineering Zhejiang University

Cavitation is the formation of vapor bubbles within a liquid where the flow dynamics causes the local static pressure to drop below the vapor pressure. The so-called full cavitation model (FCM) developed by Singhal has been widely used in numerical modeling of the cavitation flow for thermosensible and non-thermosensible fluids. Within the FCM, the bubble size is taken to be equivalent to the maximum possible value to forego the calculation of bubble number density. We developed a new cavitation model by recalculating the bubble radius in FCM to account for the effects of local pressure. The new model was obtained by combining the thermodynamic phase-change theory and the Young-Laplace equation with the assumption of thermodynamic equilibrium during the cavitation process. The cavitation calculations were performed based on the mathematical framework of the homogeneous equilibrium flow model and the transport-equation-based model for vapor phase mass fraction. The model was validated by modeling the cavitating flow of liquid nitrogen and liquid hydrogen through NASA hydrofoil and Ogive with consideration of the phase-change thermal effects. The temperature and pressure distributions with the new model are found to agree well with data from existing experimental studies, as well as the simulations with the FCM.

关键词：空化流动热力学理论相变理论低温液体建模热力学平衡空化模型气泡半径

Investigation on regenerator temperature inhomogeneity in Stirling-type pulse tube cooler

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Chinese Science Bulletin 2009年第6期54卷 986-991页

作者： SUN DaMing MARC Dietrich GUENTER Thummes qiu limin Institute of Refrigeration and Cryogenics of Zhejiang University Hangzhou 310027 China Institute of Applied Physics University of Giessen Giessen D-35392 Germany TransMIT-Centre for Adaptive Cryotechnology and Sensors Germany

Regenerator is one of the most crucial components to pulse tube cooler (PTC) and thermoacoustic engine. As such regenerator is scaled up to high-power, the thermal and hydrodynamic communication transverse to the acoustic axis gets weaker and weaker. Under this condition, any unsymmetric factor could cause serious instability to the cooler or engine, which degrades their performance. Investigation has been carried out on a high-power two-stage thermal-coupled U-shape Stirling-type PTC. By detailed circumferential temperature measurements along the middle heat exchanger and second stage regen-erator, a kind of temperature inhomogeneity caused by unsymmetric pre-cooling effect of inter-stage thermal bridge was found in the lower part of the regenerator of the PTC. The temperature inhomoge-neity originating from the middle heat exchanger of the second stage regenerator amplified itself in the lower part of the regenerator and then internal streaming formed. The maximal radial temperature dif-ference could reach 30―40 K. Experimental results show that the temperature inhomogeneity intensi-fies with increased pre-cooling power and its direction can be reversed by changing the pre-cooling effect of the first stage PTC to heating effect by using external thermal load. This research shows that it is important to maintain the heating or cooling effects of heat exchangers uniform in high-power re-generative coolers and engines.

关键词：再生温度不均匀性脉管制冷机林型 PTC公司热声发动机中间换热器冷却效果

Effects of surface tension on bubble growth in an extensive uniformly superheated liquid

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Chinese Science Bulletin 2011年第30期56卷 3191-3198页

作者： ZHANG XiaoBin XIANG ShiJun CAO XiaoLi qiu limin Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

The study of bubble growth in an extensive pool of liquid provides considerable insight into the mechanisms that play a role in bubble growth near a heated surface and in the cavitation phenomenon. This work focuses on analyzing the effects of surface tension on the growth rate for the thermally controlled stage of a single bubble in such a liquid. The conservation of energy equations, including the internal energy term for the bubble and that within boundary layer around it, are numerically solved. The complete temporal variations of the bubble in water and liquid nitrogen are investigated based on the assumption that the bubble growth is controlled only in sequence by inertia and heat. Thus, the two stages are subject to the continuity of the bubble growth, while the inertia-controlled stage is only formulated by the well-known Rayleigh solution. The thickness of the boundary layer around the bubble is also determined. The results are comparable with the Plesset-Zwick models and Forster-Zuber models, as well as available experimental data. It is found that the influence of internal energy on the rate of bubble growth is small enough to be ignored; however, the accumulative effects of the surface tension are significant and increase with a decrease in the degree of superheat.

关键词：表面张力气泡生长过热度液体均匀能量方程惯性控制泡沫层

Validation of dynamic cavitation model for unsteady cavitating flow on NACA66

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Science China(Technological Sciences) 2014年第4期57卷 819-827页

作者： ZHANG XiaoBin ZHANG Wei CHEN JianYe qiu limin SUN DaMing Institute of Refrigeration and Cryogenics Zhejiang University

Unsteady cavitating flow is extremely complicated and brings more serious damages and unignorable problems compared with steady cavitating *** has become a practical way to model cavitation;however,the popularly used full cavitation model cannot reflect the pressure-change that the bubble experiences during its life path in the highly unsteady flow like cloud *** a dynamic cavitation model(DCM)is proposed and it has been considered to have not only the first-order pressure effects but also zero-order effect and can provide greater insight into the physical process of bubble producing,developing and collapsing compared to the traditional cavitation *** has already been validated for steady cavitating flow,and the results were ***,DCM is designed and supposed to be more accurate and efficient in modeling unsteady cavitating flow,which is also the purpose of this *** basic characteristic of the unsteady cavitating flow,such as the vapor volume fraction distribution and the evolution of pressure amplitude and frequency at different locations of the hydrofoil,are carefully studied to validate *** is found that not only these characteristics mentioned above accord well with the experimental results,but also some detailed transient flow information is depicted,including the re-entrant jet flow that caused the shedding of the cavity,and the phenomenon of two-peak pressure fluctuation in the vicinity of the cavity closure in a *** numerical results validate the capability of DCM for the application of modeling the complicated unsteady cavitating flow.

关键词： unsteady cavitation dynamical cavitation model NACA66 hydrofoil