采用混合工质的热声驱动脉管制冷实验研究

在计算了惰性气体二元混合工质的热力学参数之后,采用氦-氩混合气体作为工质来提高热声驱动脉管制冷的性能。实验结果表明,热声驱动脉管制冷机采用适当配比的氦-氩工质可获得比纯氦更加优越的制冷性能。     

径流式氨水混合工质透平热力设计和数值模拟

为了更好地研究氨水混合工质透平,提升Kalina循环系统整体性能,对径流式氨水混合工质透平进行了一维热力学设计,并使用BladeGen、TurboGrid和ANSYS CFX软件进行三维数值模拟;将一维和三维建模方法分别与参考文献案例进行对比验证,并比较了透平一维热力计算与三维模型数值模拟的结果。结果表明：径流式氨水混合工质透平的性能通过热力设计模型估算,可大幅降低计算成本;透平一维热力计算与三维模型数值模拟得到的参数基本一致,所得透平等熵效率分别为84.67%和88.75%;工质在透平流道内流动均匀且无明显旋涡。     

径流式氨水混合工质透平热力设计和数值模拟

为了更好地研究氨水混合工质透平,提升Kalina循环系统整体性能,对径流式氨水混合工质透平进行了一维热力学设计,并使用BladeGen、TurboGrid和ANSYS CFX软件进行三维数值模拟;将一维和三维建模方法分别与参考文献案例进行对比验证,并比较了透平一维热力计算与三维模型数值模拟的结果。结果表明：径流式氨水混合工质透平的性能通过热力设计模型估算,可大幅降低计算成本;透平一维热力计算与三维模型数值模拟得到的参数基本一致,所得透平等熵效率分别为84.67%和88.75%;工质在透平流道内流动均匀且无明显旋涡。     

可利用低品位热源的热声驱动脉管制冷机

针对原有热声驱动脉管制冷机实验装置,改进了板叠冷端夹套式水冷却器内部的丝网填料,进一步优化了小孔阀和双向进气阀的开度,获得了116．4K的最低制冷温度。通过操作脉管制冷机双向进气阀,使系统的起振温度从560℃降低为370℃,为低品位能源的利用创造了条件。     

124K热声驱动的脉管制冷机

热声压缩机是一种利用热能（如太阳能集热、废热等）进行驱动的新型驱动器。自行研制的驻波型热声压缩机驱动脉管经过改进后，以氦为工质，取得了124.3K的制冷温度。此外，该文还讨论了热声压机系统中的水冷却存在的问题以及它对系统整体性能的影响，并对热声机的应用前景进行了展望。     

618 kW氦氙混合工质向心透平气动设计及分析

本文针对空间核电源系统中高效、轻质的向心透平,采用一维设计结合三维数值计算的方法,设计出以氦氙混合气体为工质的向心透平.使用ANSYS CFX对向心透平的气动特点以及流场特性进行了数值模拟,分析了叶轮内部流动和损失分布情况,数值结果显示出所设计的向心透平有较好的气动性能,效率为84.4％,功率为618.3 kW,本文还...     

混合集箱结构优化数值模拟

本文采用数值模拟方法分析集箱管接头的排布情况对介质混合过程的影响,研究表明,集箱管接头的合理排布可以提高介质的混合均匀性和流畅性。     

一种新型高温热泵混合工质的循环性能

对一种ODP(臭氧破坏势)为零的新型环保非共沸混合工质M1,在冷凝温度范围为80~110°C、循环温升为45°C的高温热泵工况下,进行了循环性能的理论和实验研究。理论循环性能分析表明,M1的综合性能优于传统工质CFC114;实验结果表明,M1系统的制热量Q和循环性能系数COP随工况温度的升高而提高。实验中,M1的最高平均冷凝温度达到102.3°C,相应热输出温度为103.0°C,冷凝压力和排气温度分别为1.951 MPa和119.0°C,都在安全应用的限制范围内。     

预混合燃烧过程的数值模拟研究

对预混合燃烧降低碳烟形成的机理进行了数值模拟,并与仅有主喷射的燃烧过程的数值模拟计算结果进行对比,结果证明采用预混合燃烧确能降低柴油机碳烟形成。     

甲醇-柴油混合燃料燃烧的数值模拟

本文根据柴油机燃烧过程的数学模型,将Chemkin中甲醇燃烧动力学反应机理导入Fluent软件中,对各种比例下的甲醇柴油微乳液进行了燃烧模拟计算,并用S195柴油机在台架上对计算值进行测试验证。结果表明:数值模拟的方法可靠。在不改动柴油机结构的情况下,甲醇含量影响燃烧效果,低甲醇含量可以提高燃烧效率,高甲醇含量降低燃烧效率,甲醇含量为10%时最佳。     

Three-dimensional numerical simulation of the basic pulse tube refrigerator

A three-dimensional physical and numerical model of the basic pulse tube refrigerator (PTR) was developed. The compressible and oscillating fluid flow and heat transfer phenomenon in the pulse tube were numerically investigated using a self-developed code. Some cross-section average parameter variations such as velocity, temperature and pressure wave during one cycle were revealed. The variations of velocity and temperature distributions in the pulse tube were also analyzed in detail for further understanding of the working process and refrigeration mechanism of PTRs. __________ Translated from Journal of Engineering Thermophysics, 2006, 27(5): 737–740 [译自: 工程热物理学报]     

Dynamic Experimental Study of a Multi—bypass Pulse Tube Refrigerator with Two—bypass Tubes

INTRoDUCTIONAfterthebasicpulsetuberefrigeratorwasfirstin-ventedbyGmerdandLongsworthl1],theorilicepulsetuberefrigeratorwasintroducedbyMikulinetal.[2]Double-inletpulsetuberefrigeratorwasreportedbyZhuetal.l3jStillothermodificationswerepresentedbyIshizakietall4landMatsubaraetal.l5]Illterestsinpulsetuberefrigeratorshavegrownrapidlyduetothefactthatithasnomovingpartsatthecoldend,soithasconsiderablesystemadvalltagesovermostoftheothertypesofrefrigeratorsinreliabilitylifetime,vibrationandcostI6-7…     

Theoretical research of convective condensation heat transfer for mixture gas on a horizontal tube

The mechanism of convective condensation heat transfer of moist mixed gas across a horizontal tube was studied in this paper. The models referring to how the liquid film flows and the heat transfers on the tube are set up by combining modified film model and Nusselt condensation theory. The effects of Re number, wall temperature, and water vapor concentration on condensation heat transfer are discussed. Results predict that the film thickness profile on the tube is influenced greatly by vapor shear force on liquid film. Local Nusselt number depends remarkably on gas phase heat resistance, which is different from pure vapor and very similar to single‐phase gas. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 324–333, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20169     

CFD simulation of a Gifford–McMahon type pulse tube refrigerator

Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as Gifford–McMahon (GM) and Stirling coolers because of the absence of moving parts in low temperature. This paper performs a two-dimensional computational fluid dynamic (CFD) simulation of a Gifford–McMahon type double inlet pulse tube refrigerator (DIPTR), operating under a variety of thermal boundary conditions. A commercial Computational Fluid Dynamics (CFD) software package Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. Helium is used as working fluid for the entire simulation. The simulated DIPTR consists of a transfer line, an after cooler, a regenerator, a pulse tube, a pair of heat exchangers for cold and hot end, an orifice valve with connecting pipe, a double inlet valve with connecting pipe and a reservoir. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary condition is sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the hot end and cold-end heat exchangers. The general results, such as the cool down behaviors of the system, phase relation between mass flow rate and pressure at pulse tube section and the temperature profile along the wall of the cooler are presented.The simulation shows the minimum decrease in temperature at cold-end heat exchanger for a particular combination of cryocooler assembly. The CFD simulation results are compared with available experimental data. Comparisons show that there is a reasonable agreement between CFD simulation and experimental results.     

Mechanism research of convective condensation heat transfer for a gas mixture flowing over a horizontal tube

The modified film model combined with Nusselt's condensation theory are used for the study of convective condensation heat transfer on a horizontal tube with moist mixed horizontal gas flows at a given speed. A theoretical model considering gas boundary layer separation was set up. The liquid film flows and the heat transfer on the tube are presented. The effects of the flow direction on condensation heat transfer are discussed. The results predict that the condensate film is so thin that the liquid phase heat resistance can be ignored. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20238     

Numerical simulation and performance optimization of a high capacity pulse tube cryocooler

Recent developments of superconductive industries require cryocoolers with cooling power higher than 1 W in the 70–80 K temperature range. High capacity pulse tube cryocoolers assure the cooling power required for operation of superconducting devices. This paper presents numerical simulation of a high capacity pulse tube cryocooler, intended to provide more than 200 W cooling power at 80 K. In this respect the behavior of the cryocooler is explained by applying the mass and energy balance equations to different components of the cryocooler. Nodal analysis technique is employed to simulate the tube section behavior numerically. To perform the system optimization the influence of key operating parameters on cryocooler cooling capacity and coefficient of performance is studied. The proposed model reports the optimum cooling capacity of 244 W at 80 K cold end temperature at frequency of 50 Hz with 3.5 kW net power delivered to the gas.     

Numerical and experimental study on contact face and shock wave motion in the receiving tube of gas wave refrigerator

The contact face and shock wave motion in an open ends receiving tube of gas waverefrigerator are investigated numerically and experimentally.The results show that,velocity of the contact face rises rapidly as gas is injected into the receiving tube,anddrops sharply after a steady propagation.However,velocity of the shock wave in thetube is almost linear.With increasing of inlet pressure,velocity of the shock waveand steady velocity of contact face also increase.In addition, time and distance ofcontact face propagation in the receiving tube become longer.     

Factors influencing the lowest refrigerating temperature of the miniature co‐axial pulse tube refrigerator

Experimental studies of the influencing factors on the lowest refrigerating temperature of a miniature co‐axial pulse tube refrigerator have been carried out in this paper. The results show that with the decrease of the mole fraction of hydrogen in the hydrogen‐helium mixture, the lowest refrigerating temperature decreases, and when the mole fraction of hydrogen is below 20%, the lowest refrigerating temperature is close to that obtained using pure helium. In addition, it is also found that the optimum frequency of the compressor is about 16.7 Hz for different hydrogen‐helium mixtures. When the charge pressure of the compressor increases, the lowest refrigerating temperature decreases; however, the decreasing trend gradually slows down with the increase of the charge pressure. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(4): 219–225, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20065     

旋流燃气灶数值模拟研究

为缩短燃气灶的研发周期、降低研发成本、进一步提高燃气灶热效率,以旋流燃气灶为对象,以甲烷为燃料,利用Fluent模拟软件,研究了锥角和锅支架高度、一次空气系数因素对燃气灶热效率的影响。模拟结果表明：旋流燃气灶热效率随这三个参数的增大均呈现出先增后减的规律,其最大值分别发生在一次空气系数为0.6、锥角为45°、锅支架高度为22.5 mm时。为确定这三个参数的不同组合对热效率的影响,采用正交试验研究了这三个参数对热效率影响的显著性。试验结果表明：一次空气系数为0.6、锥角为45°、锅支架高度为22.5 mm为最优水平组合。     

低浓度瓦斯脉动燃烧过程的数值模拟

选取k-ε湍流双方程模型、概率密度方程(PDF)湍流燃烧模型及部分预混燃烧模型,利用流体分析软件Fluent对煤矿低浓度瓦斯在Helmholtz型脉动燃烧器中的燃烧过程进行了数值模拟。通过对燃烧室内低浓度瓦斯脉动燃烧压力场和速度场的分布进行模拟研究,并与理论燃烧过程相比较,其结果表明:低浓度瓦斯脉动燃烧数值模拟结果符合实际脉动燃烧规律,说明脉动燃烧这一燃烧方式适合低浓度瓦斯的研究利用,并为以后的研究提供参考。