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71.
A simplified transient three-dimensional model for estimating the thermal performance of the vapor chambers 总被引:1,自引:0,他引:1
Yen-Shu Chen Kuo-Hsiang Chien Chi-Chuan Wang Tzu-Chen Hung Bau-Shei Pei 《Applied Thermal Engineering》2006,26(17-18):2087-2094
The vapor chambers (flat plate heat pipes) have been applied on the electronic cooling recently. To satisfy the quick-response requirement of the industries, a simplified transient three-dimensional linear model has been developed and tested in this study. In the proposed model, the vapor is assumed as a single interface between the evaporator and condenser wicks, and this assumption enables the vapor chamber to be analyzed by being split into small control volumes. Comparing with the previous available results, the calculated transient responses have shown good agreements with the existing results. For further validation of the proposed model, a water-cooling experiment was conducted. In addition to the vapor chamber, the heating block is also taken into account in the simulation. It is found that the inclusion of the capacitance of heating block shows a better agreement with the measurements. 相似文献
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本文数值模拟了圆筒燃烧室内双股同心强旋流流场及其湍流参数的分布。计算中,对Kolmogorov-Prandtl旋涡粘性系数假定中的经验系数Cμ做了初步调试,认为Cμ对不同流场及同一流场中的不同点都有可能不同,而且Cμ应具有各向异性的特性。实验结果表明:数学模型与计算方法,对模拟轴对称强旋流场是可行的。 相似文献
76.
M. Siddhartha Bhatt 《国际能源研究杂志》1990,14(2):169-180
The paper is divided into two parts. In the first part, the results of tests on 13 stoves currently being marketed in India, compared with two traditional stoves, are presented. The bulk of the tests (about 140) pertain to variation of efficiency against fuel burning rate. Also, a few tests on the variation of chimney heights (18 tests) and damper position (20 tests) were conducted. The levels of efficiency were quite low on account of improper dimensioning of the stoves. Except for two stoves, all recorded consistently low efficiency figures. In the second part of the paper, the results of tests on combustion chambers of different sizes, ranging from a diameter of 180 mm to 500 mm, are presented in the form of design equations. The optimum length to diameter ratio is about 0.35, and optimum height of the ash chamber is 0.2 times the height of combustion chamber. A new approach to the sizing of combustion chambers is presented. 相似文献
77.
Isabel M. Fisenne Andreas C. George Helen W. Keller 《Journal of research of the National Institute of Standards and Technology》1990,95(2):127-134
The ideal facility for assessing the quality of radon measurements at environmental levels consists of: (1) an instrument whose response to radon and its progeny is determined from measurements of a certified or standard 226Ra source, and (2) a calibration room with a known radon concentration.The linkage between these two elements and additional quality control requirements are discussed here for some Environmental Measurements Laboratory radon measurements programs. 相似文献
78.
N. Valcov L. Purghel 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2002,480(2-3):807-813
A radon monitor, able to perform the measurement of the radon and its progeny volumic activity, in a gamma-ray or natural radiation background field, was developed. The instrument consists of a 10 l ionization chamber, a high voltage source, an integrating preamplifier, a data acquisition system and a personal computer. A new method for self-calibration of Radon volumic activity measurements, based on the alpha counting with an ionization chamber is also presented. 相似文献
79.
随着电磁兼容检测技术的发展和提高,人们正针对不同的电子电器产品寻求更为简单的检测方法。该文介绍采用TEM小室进行辐射骚扰测试和辐射抗扰度测试的方法,使小尺寸的电子电器产品的电磁兼容测试更加便捷。 相似文献
80.
Wageha Awad Khaled Ghareeb Josef B?hm Jürgen Zentek 《International journal of molecular sciences》2008,9(12):2505-2514
It has been shown that DON has negative effects on the active transport of some nutrients in the small intestine of chickens. The plausible interactions between food contaminants and natural components could be high. The present study investigated the effects of DON on the presence or absence of dietary inulin on the electrophysiological response of the gut to glucose. Ussing chamber studies were conducted with isolated jejunal epithelia at the age of 35 days. Electrophysiology of the epithelia was recorded and the changes of the short-circuit current (Isc) were determined. The addition of d-glucose on the luminal side of the isolated mucosa increased (P < 0.05) the Isc in the control group and inulin supplemented group. The oligosaccharides did not increase glucose absorption in young healthy chickens compared with the controls. In the second experiment, after preincubation of tissues with DON, the addition of glucose did not increase the Isc in jejunum and colon in the control group (P > 0.05). However, in the dietary inulin supplemented group in both jejunum and colon, the addition of glucose after preincubation of tissues with DON increased the Isc, suggesting that the dietary inulin supplementation of the broilers regulated and improved the glucose absorption in the presence of DON and kept it at normal levels. 相似文献