Optimization of a Heat Pipe with a Wick and Annulus Liquid Flow

1972 ◽  
Vol 94 (2) ◽  
pp. 196-201 ◽  
Author(s):  
H. Hwang-Bo ◽  
W. E. Hilding
Keyword(s):  
Heat Pipe ◽  
Analytical Model ◽  
Liquid Flow ◽  
Flow Characteristics ◽  
Rate Of Change ◽  
The Body ◽  
Radial Heat ◽  
Axial Variation ◽  
Frictional Forces ◽  
Container Tube

An analytical model has been formulated for the parametric study of liquid flow characteristics in the heat pipe, which consists of a porous tube, a closed outer container tube, and an annulus between them. The analytical model includes the effect of the rate of change of momentum, surface tension forces, the frictional forces in the body of wicking material and at the wall, as well as the axial variation of static pressure supporting the capillary meniscus at the liquid–vapor–wick interface in the vapor passage. The length of the condenser of the heat pipe was optimized as a function of the radial heat flux rate and the ratio of the liquid flow rate in the annulus to that within the wick, Wa/Ww. The effect of pressure loss and recovery in the vapor passage of the heat pipe on the optimum length of condenser was investigated.

A NUMERICAL STUDY ON THE HEMODYNAMIC AND SHEAR STRESS OF DOUBLE ANEURYSM THROUGH S-SHAPED VESSEL

2015 ◽  
Vol 27 (04) ◽  
pp. 1550033 ◽  
Author(s):  
Mahdi Halabian ◽  
Alireza Karimi ◽  
Borhan Beigzadeh ◽  
Mahdi Navidbakhsh
Keyword(s):  
Blood Flow ◽  
Mechanical Behavior ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
The Body ◽  
Sweep Angle ◽  
Abdominal Aortic ◽  
Hemodynamic Characteristics ◽  
Refined Meshes

Abdominal aortic aneurysm (AAA) is a degenerative disease defined as the abnormal ballooning of the abdominal aorta (AA) wall which is usually caused by atherosclerosis. The aneurysm grows larger and eventually ruptures if it is not diagnosed and treated. Aneurysms occur mostly in the aorta, the main artery of the chest and abdomen. The aorta carries blood flow from the heart to all parts of the body, including the vital organs, the legs, and feet. The objective of the present study is to investigate the combined effects of aneurysm and curvature on flow characteristics in S-shaped bends with sweep angle of 90° at Reynolds number of 900. The fluid mechanics of blood flow in a curved artery with abnormal aortic is studied through a mathematical analysis and employing Cosmos flow simulation. Blood is modeled as an incompressible non-Newtonian fluid and the flow is assumed to be steady and laminar. Hemodynamic characteristics are analyzed. Grid independence is tested on three successively refined meshes. It is observed that the abrupt expansion induced by AAA results in an immensely disturbed regime. The results may have implications not only for understanding the mechanical behavior of the blood flow inside an aneurysm artery but also for investigating the mechanical behavior of the blood flow in different arterial diseases, such as atherosclerosis.

Numerical Simulation on Heat Transfer and Fluid Flow Characteristics of Arrays With Nonuniform Plate Length Positioned Obliquely to the Flow Direction

1998 ◽  
Vol 120 (4) ◽  
pp. 991-998 ◽  
Author(s):  
L. B. Wang ◽  
G. D. Jiang ◽  
W. Q. Tao ◽  
H. Ozoe
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Numerical Results ◽  
The Body ◽  
Number Range ◽  
Plate Length ◽  
Nonuniform Plate ◽  
Short Plate

The periodically fully developed laminar heat transfer and pressure drop of arrays with nonuniform plate length aligned at an angle (25 deg) to air direction have been investigated by numerical analysis in the Reynolds number range of 50–1700. The body-fitted coordinate system generated by the multisurface method was adopted to retain the corresponding periodic relation of the lines in physical and computational domains. The computations were carried out just in one cycle. Numerical results show that both the heat transfer and pressure drop increase with the increase in the length ratio of the long plate to the short plate, and decrease with the decrease in the ratio of transverse pitch to the longitudinal pitch. The numerical results exhibit good agreement with available experimental data.

CFD analyses of liquid flow characteristics in a rotor-stator reactor

2018 ◽  
Vol 134 ◽  
pp. 186-197 ◽  
Author(s):  
Yi Ouyang ◽  
Siwen Wang ◽  
Yang Xiang ◽  
Zemeng Zhao ◽  
Jiexin Wang ◽  
...  
Keyword(s):  
Liquid Flow ◽  
Flow Characteristics ◽  
Cfd Analyses

Flow characteristics of misfired gas in the exhaust manifold of a spark ignition engine

2000 ◽  
Vol 214 (4) ◽  
pp. 373-381 ◽  
Author(s):  
Y Chung ◽  
H Kim ◽  
S Choi ◽  
C Bae
Keyword(s):  
Analytical Model ◽  
Oxygen Concentration ◽  
Oxygen Sensor ◽  
Flow Characteristics ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Exhaust Manifold ◽  
Cycle Simulation ◽  
Twin Peaks ◽  
Wide Range

Misfiring in spark ignition engines should be avoided, otherwise unburned fuel and oxygen are brought into the catalyst, and subsequent combustion greatly increases the temperature, possibly resulting in immediate damage to the catalyst. As a new concept of misfire detection method, the signal fluctuation of a wide-range oxygen sensor has been introduced to monitor the fluctuation of the oxygen concentration at the exhaust manifold confluence point. The current research aims to develop a tool that is capable of predicting the variation in oxygen concentration at the exhaust manifold confluence point, and to investigate the flow characteristics of the misfired gas in the exhaust manifold under misfiring conditions in a cylinder. The oxygen concentration at the confluence point could be predicted by comparing the gas flowrate from the misfiring cylinder with the total exhaust gas flowrate. The gas flowrates from each of the cylinders were calculated using a one-dimensional engine cycle simulation including a gas dynamic model of the intake and exhaust systems. The variation in oxygen concentration was also determined experimentally using a fast-response hydrocarbon analyser. The trend of the oxygen concentration fluctuation calculated by the analytical model was compared with the experimental results. The analytical model could duplicate the measured trend of the fluctuation of oxygen concentration at the confluence point, which was characterized by twin peaks for one misfiring. The twin peaks are mainly caused by the mixing of the misfired gas with the burned gas from normally operating cylinders. The effects of engine load and speed on the characteristics of the variation in oxygen concentration were also investigated analytically and experimentally.

scholarly journals Batch spawning facilitates transfer of an essential nutrient from diet to eggs in a marine fish

2013 ◽  
Vol 9 (5) ◽  
pp. 20130593 ◽  
Author(s):  
Lee A. Fuiman ◽  
Cynthia K. Faulk
Keyword(s):  
Fatty Acids ◽  
Essential Fatty Acids ◽  
Maternal Diet ◽  
Short Interval ◽  
Rate Of Change ◽  
The Body ◽  
Sciaenops Ocellatus ◽  
Diet Shift ◽  
Spawning Site ◽  
Batch Spawning

Fatty acid composition of eggs affects development, growth and ecological performance of fish embryos and larvae, with potential consequences for recruitment success. Essential fatty acids in eggs derive from the maternal diet, and the time between ingestion and deposition in eggs is ecologically important but unknown. We examined the dynamics of diet–egg transfer of arachidonic acid (ARA) in the batch-spawning fish, red drum ( Sciaenops ocellatus ), by measuring ARA concentrations in eggs after a single diet shift and during a period of irregular variations in diet. ARA concentrations in eggs changed within 2–16 days of a diet shift. The rate of change was proportional to the magnitude of the shift, with no evidence of equilibration. These results are not consistent with eggs being assembled entirely from accumulated body stores. The immediate source of ARA in eggs appears to be the recent diet. We propose that batch spawning produces rapid diet–egg transfer of ARA because it removes large amounts of fatty acids from the body and prevents equilibration. The immediacy of the diet–egg connection suggests that spawning migration combined with short-interval batch spawning may have evolved to take advantage of nutrients critical for offspring survival that are available at the spawning site.

CFD analysis of gas–liquid flow characteristics in a microporous tube-in-tube microchannel reactor

2018 ◽  
Vol 170 ◽  
pp. 13-23 ◽  
Author(s):  
Wen-Ling Li ◽  
Yi Ouyang ◽  
Xue-Ying Gao ◽  
Chen-Yu Wang ◽  
Lei Shao ◽  
...  
Keyword(s):  
Liquid Flow ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Microchannel Reactor ◽  
Gas Liquid Flow
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