Experimental investigation on the cooling helium circulation of the internal purifier pilot plant

The internal purifier is utilized to remove impurities from impure helium, keep the helium free of any gaseous contaminants. However, there is few report on the performance improvement of the internal purifier. In this paper, we present a novel circuit of the experimental platform with GM cryocooler providing a separated cooling helium circulation as the refrigeration power supply for investigating the performance the internal purifier. Namely, that circuit is easily constructed by extracting a small stream of helium from the high-pressure side of the GM cryocooler serving as the cooling helium circulation. The experiment is then carried out to test the mass flow and the temperature of the cooling helium circulation. The impact of the modification on the cold head is also estimated. It is finally demonstrated that the circuit is sufficient to guarantee the cooling supply of the whole experimental system, which means that the modification is suitable and efficient.     

Characteristic features of evaporative cooling of droplets in high-temperature flows

Numerical investigation of the evaporative cooling of water droplets in a high-temperature gas flow (temperature above 1000°C) has been carried out for two limiting regimes: a continuous medium and a free-molecular regime. The results of modeling have shown that with a small content of water vapor in the flow, due to evaporative cooling the droplet temperature attains a stationary value that is lower than the stream temperature by hundreds of degrees.     

热金属表面多喷嘴风冷过程气-固耦合传热模拟

目的 获得多喷嘴风冷过程的界面换热系数,并研究风冷工艺参数对界面换热的影响规律.方法 基于Fluent软件对三喷嘴强制风冷传热过程进行"气-固"耦合分析,获得高压气流的流速场和钢板表面温度场.基于"气-固"耦合分析得到钢板表面平均温度曲线,利用自开发的反传热软件计算得到"气-固"耦合界面换热系数,并将界面换热系数以第三类边界条件施加在钢板表面进行瞬态传热分析.结果 对于直径为4 mm的喷嘴,当喷嘴间距为10～16 mm时,喷嘴间距对高压气体的流速场影响较大,气流的卷吸效应随着喷嘴距离的增大而增强;喷嘴间距对界面换热系数影响较小,喷嘴至钢板表面的距离对界面换热系数影响较大;随着喷嘴至钢板表面距离的增大,各股气流逐渐汇合为一股,各股气流的滞止区也逐渐汇合,钢板表面温度更加均匀;将界面换热系数以第三类边界条件施加在钢板表面进行瞬态传热分析,得到的钢板表面温度与"气-固"耦合分析得到的钢板表面平均温度曲线吻合得较好.结论 获得的界面换热系数可为多喷嘴风冷过程数值模拟提供可靠的数据,保证温度场的求解精度.     

Heat exchange in the flow of a hypersonic rarefied gas stream over a blunt wedge

The cooling of the leading edge of a blunt wedge over which a hypersonic rarefied gas stream flows is studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 28, No. 5, pp. 788–792, May, 1975.     

A study concerning the efficiency of film cooling under real conditions in various moving systems

The results are analyzed of an experimental study concerning the efficiency of film cooling under conditions of a zero-gradient and an accelerated flow of the main and the injected stream.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 1, pp. 46–49, January, 1972.     

Influence of the incompressible stream temperature on cooling of a hot wire

Results are presented of an experimental investigation of the cooling of the hot wire of a thermoanemometer in an air stream for different wire and flow temperatures.Translated from Inzhenerno-Fizieheskii Zhurnal, Vol. 38, No. 1, pp. 55–61, January, 1980.     

Numerical simulation of counter-flow wet-cooling towers

Cooling towers are used to cool a warm water stream through evaporation of part of the water into an air stream. A cooling tower consists of three zones; namely spray, packing and rain zones. In cooling towers, a significant portion of the total heat rejected may occur in the spray and rain zones. These zones are modeled and solved numerically using a computer code. The developed models of these zones are validated against experimental data. For the case study under consideration, the error in calculation of the tower volume is 1.5% when the spray and rain zones are neglected. This error is reduced to 1.1% and 0.25% as the spray and rain zones are incorporated in the model, respectively. Furthermore, the effect of the Lewis factor on the performance prediction of wet-cooling towers is investigated using Bosnjakovic equation.     

Indirect evaporative combined inlet air cooling with gas turbines for green power technology

Different inlet air cooling systems are usually used with gas turbines. A new form of inlet air cooling called the indirect evaporative cooling system (IECS) has been investigated in this work. This system is a combination of a humidifier with a vapor compression or absorption cooling system for part of the total air i.e. the secondary air stream. The net power produced from the gas turbine on a hot day (45 °C) by using combined (IECS) with absorption chillers showed an increase in power and efficiency by 15% and 9%, respectively; its recovery period is suitable for all environmental conditions. For IECS combined with vapor compression mechanical chillers showed an increase in power and efficiency by about 7.81% and 2.24%, respectively, but its recovery period made it suitable only for hot and humid conditions. The IECS has lower chiller's capital cost by about 25% (mechanical chiller) and 40% (absorption chiller).     

An investigation into the heat and mass transfer of a liquid evaporating from a capillary-porous body

A theoretical analysis is presented for the process of heat and mass transfer in the case of a liquid evaporating from a capillary-porous body into an approaching gas stream. The method of the experimental investigation into this process is described. The excellent agreement between the experimental and theoretical data makes it possible to use the resulting quantitative relationships to calculate the heattransfer coefficients in the case of intermittent cooling.     

Thermodynamic analysis of different two-stage transcritical carbon dioxide cycles

The aim of this paper is the thermodynamic evaluation and optimisation of different two-stage transcritical carbon dioxide cycles. Five different cycles are studied: basic single-stage cycle, single-throttling with two-stage compression cycle, split cycle, phase separation cycle and single-stage cycle coupled with a gas cooling circuit. Each basic cycle is analysed for the effect of internal heat transfer between different streams of refrigerants. In the case of two-stage compression, intermediate cooling between the compressor stages is present. An analysis on the Plank cycle for intermediate pressure higher than critical one is performed. Each cycle is optimised with regards to energy performance, calculating the optimal values of both the upper and the intermediate pressures. In the case of split cycle, the ratio of the mass flow rate in the main stream to the one in the auxiliary stream is also optimised.     

Numerical simulation of a porous cooling effect observed when a hypersonic stream of viscous gas with a decaying shock wave flows round a wall

The concept of porous cooling observed when a hypersonic stream of viscous gas with a decaying shock wave flows round a wall is substantiated by means of a finite-difference solution of the Reynolds equations, closed by using a two-parameter dissipative turbulence model. Pis’ma Zh. Tekh. Fiz. 23, 46–50 (April 12, 1997)     

Personal cooling belt

This paper reports development of a personal cooling belt using a short vortex tube. The vortex tube uses compressed air as the working substance and converts about half of it into a cold stream which circulates in the waist belt. Trials conducted on various individuals resulted in satisfactory performance.     

Solid atomization technology and process of molten metal and alloy

A novel solid atomization technology has been developed with a high-velocity gas jet stream containing solid salt particles as the atomization medium. Metal and alloy powders with a finer particle size, a narrower size distribution and a higher cooling rate than those of the conventional gas atomization technology have been produced by this technology. The affecting factors of the particle size of as-prepared metallic powders have been analyzed, especially the influence of the state of NaCl particles.     

一种新型的雾化方法

固体雾化是一种新型的制粉方法 ,通过改变雾化介质可以改善雾化效果。本文介绍固体雾化的理论依据及总结固体雾化的主要特征 ,研究表明在同等气体压力和流量的条件下 ,采用含有固体颗粒盐的高速气流对金属液体和合金进行雾化破碎 ,所得粉末比不含固体颗粒盐的高速气流制得的粉末 ,粒度细的多 ,粉末粒度分布窄 ,粉末冷却速度较大     

撞击流技术与空调流体动力式喷水室的研究

综述了撞击流技术的理论研究和应用进展，系统介绍了应用撞击流蒸发冷却空气的设备-一流体动力式喷水室的工作原理，结构特点，性能参数及应用情况，展望了撞击流技术的应用前景。     

Vibrating Breakup of Jet for Uniform Metal Droplets

Uniform droplet formation from capillary stream breakup provides promising opportunities for many applications such as solder balls manufacturing, circuit board printing and rapid prototype manufacturing. In this study an apparatus capable of making monosize metal spheres by vibrating breakup has been developed. The droplets were electrically charged to avoid collision and merging with one another during flight. As a result, uniformly sized tin powders （180 μm in diameter） were obtained after cooling and solidification.     

Erosion Corrosion on Oil Coolers for Navy Ships

Incorrect material selection does not always lead to corrosion. In addition to an inferior selection of materials, unsuitable operating conditions and poor design also contributed to the presented failure. A combination of erosion and corrosion caused a leak in an oil cooler of a Navy ship. Because there was no welding seam between the deflectors and tube plate on the carbon steel cooler, cooling water could stream between them, and the flow rate became excessive. This caused erosion on the tube plate. In addition, the repeated change of the cooling liquid after servicing caused a uniform corrosion attack.     

Numerical solution of a heat-transfer problem

Using numerical calculations, a study is made of the relation between the mean temperature of a surface and the heat flux, in cooling a solid with a stream of liquid.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 15, No. 6, pp. 1047–1058, December, 1968.     

Heat and mass transfer from a laminar humid air stream to a plate at subfreezing temperatureTransfert de chaleur et de masse entre un écoulement laminaire d'air humide et une plaque à une température inférieure au point de congélation

Processes involving the transfer of heat from a humid air stream in laminar flow to a horizontal plate with the simultaneous deposition of frost is of importance in a variety of refrigeration equipment. The accumulating frost layer impedes the heat flow to the cooling surface. The present study is carried out to determine both theoretically and experimentally the factors that influence, frost formation on a cold surface and to correlate the Nusselt and Sherwood numbers with these factors.Experiments were conducted on a 600 mm long, flat horizontal plate, the Reynolds number and the relative humidity of the impinging air stream were varied from 30 000 to 140 000 and from 40% to 60% respectively, while the average surface temperature was near - 18°C. Empirical correlations of the Nusselt number and Sherwood number are presented.     

Heat and mass transfer from a laminar humid air stream to a plate at subfreezing temperature

Processes involving the transfer of heat from a humid air stream in laminar flow to a horizontal plate with the simultaneous deposition of frost is of importance in a variety of refrigeration equipment. The accumulating frost layer impedes the heat flow to the cooling surface. The present study is carried out to determine both theoretically and experimentally the factors that influence, frost formation on a cold surface and to correlate the Nusselt and Sherwood numbers with these factors.Experiments were conducted on a 600 mm long, flat horizontal plate, the Reynolds number and the relative humidity of the impinging air stream were varied from 30 000 to 140 000 and from 40% to 60% respectively, while the average surface temperature was near - 18°C. Empirical correlations of the Nusselt number and Sherwood number are presented.