Heat transfer of multiple-void slabs heated by air

It is experimentally shown that if the initial temperature of the air is taken as the determining temperature, then the heat transfer for three regimes of motion is satisfactorily described by a single generalized relationship.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 5, pp. 781–783, November, 1981.     

Heat transfer due to the interaction between condensed particles and a wall

An approximate method of assessing the heat transfer associated with collisions between the solid particles in a flow of gas suspension and the walls of the channel is considered.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 3, pp. 456–462, September, 1976.     

Improvement in performance of cryocoolers as condensers

Modifications to the cold head of a Cryomech PT410 pulse tube cryocooler, being used as a helium condenser, have led to an increase in liquefaction rate from 12.8 to 21.4 L/day. These modifications are the first experimental results from attempts to enhance the use of natural convective heat transfer to precool the helium vapour prior to liquefaction.     

Heat transfer from flat bodies on an air cushion

Results of experimental studies of the heat transfer and hydrodynamics of plates floating on an air cushion are presented and discussed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 1, pp. 26–31, July, 1977.     

冰箱用箱壁式冷凝器的热路分析

为了对冰箱冷凝器结构的优化设计提供理论依据，利用通用有限元软件ANSYS对箱壁式冷凝器进行了建模、求解。在分析中，考虑了铝箔对传热的影响；同时，考虑到在通常情况下冷凝管和冰箱的外壁平板之间的线接触会影响冷凝器的散热。因此，对冷凝管与箱壁平板的线接触进行了改进，采用凹槽结构的接触形式，并分析接触角度对散热的影响。结果显示：铝箔在冷凝管的散热中是一个重要的热路。如果不考虑铝箔的影响，计算所得的换热量将偏小8％左右；冷凝器的管材对换热效果影响不大，采用铜管比钢管的换热效果增大不到1％；增加冷凝管与外壁的接触面积可以提高换热效果，但是增加幅度并不明显；同时计算结果也表明，冷凝器通过发泡层传入冰箱内部的热量约占冷凝器总负荷的12％。     

Application of air cooled condensers in European supermarket refrigeration systems

The application of air cooled condensers in European supermarket refrigeration systems is discussed. Compressors are usually hermetic or open types with capacities in the 5 kW range. Advantages over water-cooled systems are lower initial and operating costs and easier maintenance. There are, however, a number of problems, primarily sensitivity to ambient air temperatures which causes high condensing temperatures in hot summer weather and consequently a substantial increase in energy demand. Problems can also arise when the air temperature falls below 0°C; the condensing pressure must be maintained by fan speed control, air flow control or reduction of active heat transfer surface by flooding.     

A new method of measuring air leakage into steam condensers

This scheme measures the total pressure and temperature in air suction pipelines of steam condensers with air added in calibrated steps, for two different combinations of pumps. With the aid of steam tables, air partial pressures are plotted against added air leakages. This allows the leakage of the set to be found, and a temperature obtained from the plots shows whether the water vapour is saturated or superheated. The method is useful in routine checks, for showing how much of the leakage is into particular parts, so that remedial action can be taken, and for revealing if water temperatures are affecting pump displacements and augmenting air pressures within condensers, in which case fuel may be saved.     

Heat transfer in the flow of low-density air in narrow channels

Results are given from measurements on air flow in narrow channels; relationships in dimensionless terms are derived for the heat transfer over a wide range in speed (1–120 m/sec) and in pressure (1 · 10⁵ > P > 1.33 · 10³) N/m².Notation V volume flow rate of air - N total number of buret divisions - P₀ pressure in measuring tank - l length of measuring section of buret - t time of oil column rise to the height h_i - n number of buret division corresponding to_i - _o, _m specific weights of oil and mercury - c scale division of buret - h₂ height of oil drop in measuring cylinder - v₀ total volume of system from needle throttle to heat exchanger inlet - P_p pressure at heat exchanger inlet - T_p, T₀ temperature at heat exchanger inlet and of surrounding air - G flow rate in mass terms - c_p mean specific heat of air - t temperature variation over measuring section - Nu, Re Nusselt and Reynolds numbers - l, d length and diameter of channel Translated from Inzhenerno-Fizicheskii Zhurnal, vol. 20, No. 5, pp. 879–883, May, 1971.     

On the extension of a crack due to non-uniform internal pressure

The effect of a non-uniform internal pressure on crack extension has been studied with the help of Somigliana's method. The case when the non-uniform internal pressure arises as a consequence of the normal displacement being specified over a part of the crack surface, the remaining part being subject to a uniform surface pressure, has also been considered.

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Résumé L'effet d'une pression interne non-uniforme sur l'extension d'une fissure a été étudié à l'aide de la méthode Somigliana. On a également considéré le cas qui correspond à une pression interne non-uniforme survenant en conséquence d'un déplacement normal spécifié sur une partie de la surface de la fissure tandis que la partie restante demeure sujette à une pression de surface uniforme.

     

空气冷却器空气侧百叶窗翅片强化传热性能研究

对跨临界CO2空调系统中空气冷却器空气侧的百叶窗翅片建立流固耦合的三维模型并进行数值模拟,结果表明传热和阻力特性与实验关联式吻合较好;开发新型弧形百叶窗翅片,并对不同窗翅角度和弧度的弧形百叶窗翅片进行数值分析,发现新型弧形百叶窗翅片的换热特性与压降特性较一般的百叶窗翅片都有增加,平均表面传热系数增加幅度高达9．47％,平均压降增加最大幅度为3．2％,可见新型弧形百叶窗翅片传热元件具有良好的综合传热性能。     

Heat transfer in the supercritical region at low pressure and mass velocity

Results are presented from experiments on heat transfer in the supercritical region for pressures p=0.05–0.3 MPa and low mass velocities w=16.9–168.9 kg/m².sec, i.e., for conditions characteristic of emergency and post-emergency regimes of operation of steam-generating equipment in nuclear power plants.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 5, pp. 709–715, November, 1982.     

Heat transfer from cylinder during its impact streamlining by air jets

A study is made of heat transfer from finned and smooth cylinders during impact streamlining by air jets. Criterial relations are derived for calculating the heat transfer in these cases.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 4, pp. 544–547, April, 1982.     

Heat transfer for a planar air jet striking a concave surface

Results are presented from an experimental study of the local and mean heat transfer rates when a rectangular jet enters a relatively short concave body of parabolic profile.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 5, pp. 785–790, November, 1969.     

空压机冷却器冷却效果差引起排气压力超标的分析

由于活塞式空压机二级冷却器冷却效果不佳,二级排气压力超过设计压力,造成安全阀起跳。更换二级冷却器,解决了此故障。介绍了保证活塞式空压机冷却器冷却效果的操作方法。     

Heat and mass transfer in condensation of water vapor from moist air

Results of an analysis of heat and mass transfer in condensation of vapor from moist air are presented. The computational model is based on the solution of integral relations of boundary-layer energy and diffusion using the analogy of heat- and mass-transfer processes. The effect of the temperature and concentration boundary conditions on the relation of the components of the heat flux on the wall is analyzed. Results of calculations are compared to available experimental data. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 5, pp. 788–794, September–October, 1998.     

来流不均匀性对冷凝器性能影响的数值研究

基于相关文献提出的冷凝器分布参数模型,运用该模型分析了不同来流分布、不同冷媒流量、不同流程布置以及不同换热管排数时来流不均匀性对冷凝器性能的影响,得出了一些实用性的结论。研究表明：不同的空气来流分布形式对冷凝器性能的影响程度不同,不均匀程度的大小可以由不均匀因子τ来衡量,当来流不均匀程度增大时,不均匀因子τ增大,冷凝器换热性能恶化,整体性能下降。     

Noise due to particle distributions in metal-particle media

Noise is a concern when it comes to storing data because noise can cause a corrupted signal and, therefore, lost data. Micromagnetic simulation was used to gain insight and understanding of particulate media noise due to nonuniform particle distribution. These distributions result in a spatial fluctuation of the anisotropy field and orientation of the particles, which introduces randomness into the recording process. The effect of the randomness (i.e., noise) on the recording process was studied, as were effects of reduced media thickness and improved particle alignment on the noise level and record nonlinearity. Effect of the noise on write-equalized recordings was also investigated. The focus of the paper is on thin metal-particle media     

Impurity distributions in crystals due to growth-rate fluctuations

Balance equations for the second moments of the velocity and temperature fluctuations are used to examine the effects of turbulent natural convection on the uniformity of impurity distributions in crystals.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 5, pp. 806–810, May, 1986.