The UGKS Simulation of Microchannel Gas Flow and Heat Transfer Confined Between Isothermal and Nonisothermal Parallel Plates

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Lianfu Dai ◽  
Huiying Wu ◽  
Jun Tang
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Gas Flow ◽  
Flow Direction ◽  
Channel Height ◽  
Parallel Plates ◽  
Gas Temperature ◽  
Gas Velocity ◽  
Microscopic Mechanism ◽  
Flow And Heat Transfer

Abstract The unified gas kinetic scheme (UGKS) is introduced to simulate the near transition regime gas flow and heat transfer in microchannel confined between isothermal and nonisothermal parallel plates. The argon gas is used and its inlet Knudsen number (Knin) ranges from 0.0154 to 0.0715. It is found that: (1) both microchannel gas flows under isothermal and nonisothermal parallel plates display a trend of speed acceleration and temperature decrease along flow direction, for which the microscopic mechanism explanation is first proposed; (2) inlet gas streamlines under nonisothermal plates condition deviate from the parallel distributions under isothermal plates condition due to the dual driving effects of pressure drop along flow direction and temperature difference along cross section; (3) gas temperature, pressure, density and viscosity distributions along cross section under nonisothermal plates condition deviate from the parabolic distributions under isothermal plates condition, while the gas velocity keeps the parabolic distribution due to the effect of Knudsen layer; (4) as channel height increases or channel length and gas molecular mean free path decrease, the gas temperature distribution along cross section under nonisothermal plates condition tends to transition from linear to curve one due to the decreasing effect of heat transfer along cross section and increasing effect of gas acceleration along flow direction, this transition from linear to curve one becomes more obvious along flow direction. (5) the gas velocity under nonisothermal plates condition decreases with the increase of inlet gas temperature (Tin), lower plate temperature (Tl) and Knin, while the gas temperature increases with the increase of Tin, Tl and Knin.

Effects of Triangular Rough Elements on Flow and Heat Transfer in Micro-Channels

2008 ◽  
Author(s):  
Yan-Hui Feng ◽  
Ai-Guo Wang ◽  
Lin Lin ◽  
Xin-Xin Zhang ◽  
Xin Liu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Rarefied Gas ◽  
Flow Direction ◽  
Leeward Side ◽  
Parallel Plates ◽  
Gas Temperature ◽  
Local Pressure ◽  
Flow And Heat Transfer ◽  
Micro Channels

The flow and heat transfer of rarefied gas in rough microchannels, which are confined between two infinite large parallel plates with uniformly distributed triangular rough elements, are simulated by DSMC method with Delaunay triangulation meshes. Analysis and comparison are carried out on smooth and rough channels with rough elements of different size or/and distribution density. Roughness in micro-channels affect the gas flow and heat transfer greatly. As the size or/and the number of rough elements increases, the gas velocity jumps more seriously, even being accompanied by some vortices; furthermore, the gas temperature increases, but both the mass flux and the heat transfer rate decrease. In the flow direction, the gas temperature rises first and then falls; the local pressure increases at the windward of rough elements and decreases at the leeward side; moreover, the heat flux at the surface shows violent fluctuation, that is, the heat flux at the rough element surface is much smaller than that at the channel wall surface.

Numerical Investigation of the Effect of Waste Heat Extracting Location on Temperature Distribution

2011 ◽  
Vol 354-355 ◽  
pp. 361-364
Author(s):  
Zhan Xu Tie ◽  
Hai Xia Li ◽  
Xiao Dian Guo
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Gas Flow ◽  
Waste Heat ◽  
Cement Clinker ◽  
Cement Kiln ◽  
Gas Temperature ◽  
Flow And Heat Transfer ◽  
Grate Cooler ◽  
High Temperature Gas

The numerical model was established to simulate the gas flow and heat transfer in cement grate cooler. It is useful to increase the gas temperature when the extracting exit position is close to the cement kiln end. The appropriate position of the extracting high temperature gas is about 5 m far away from the cement clinker inlet.

SHOCK WAVE INTERACTION NEAR A CYLINDER ALIGNED NORMAL TO A BLUNTED PLATE—PART I: GAS FLOW AND HEAT TRANSFER ON A PLATE NEAR A CYLINDER

2018 ◽  
Vol 49 (2) ◽  
pp. 105-118
Author(s):  
Volf Ya. Borovoy ◽  
Vladimir Evguenyevich Mosharov ◽  
Vladimir Nikolaevich Radchenko ◽  
Arkadii Sergeyevich Skuratov
Keyword(s):  
Heat Transfer ◽  
Shock Wave ◽  
Gas Flow ◽  
Wave Interaction ◽  
Shock Wave Interaction ◽  
Flow And Heat Transfer

scholarly journals Investigations of Flow and Heat Transfer Characteristics in a Channel Impingement Cooling Configuration with a Single Row of Water Jets

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4327
Author(s):  
Min-Seob Shin ◽  
Santhosh Senguttuvan ◽  
Sung-Min Kim
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Channel Height ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
Average Heat ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

The present study experimentally and numerically investigates the effect of channel height on the flow and heat transfer characteristics of a channel impingement cooling configuration for various jet Reynolds numbers in the range of 2000–8600. A single array consisting of eleven jets with 0.8 mm diameter injects water into the channel with 2 mm width at four different channel heights (3, 4, 5, and 6 mm). The average heat transfer coefficients at the target surface are measured by maintaining a temperature difference between the jet exit and the target surface in the range of 15–17 °C for each channel height. The experimental results show the average heat transfer coefficient at the target surface increases with the jet Reynolds number and decreases with the channel height. An average Nusselt number correlation is developed based on 85 experimentally measured data points with a mean absolute error of less than 4.31%. The numerical simulation accurately predicts the overall heat transfer rate within 10% error. The numerical results are analyzed to investigate the flow structure and its effect on the local heat transfer characteristics. The present study advances the primary understanding of the flow and heat transfer characteristics of the channel impingement cooling configuration with liquid jets.

scholarly journals Analyses on 3-D gas flow and heat transfer in ladle furnace lid

2009 ◽  
Vol 33 (6) ◽  
pp. 2646-2662 ◽  
Author(s):  
S.F. Zhang ◽  
L.Y. Wen ◽  
C.G. Bai ◽  
D.F. Chen ◽  
Z.J. Long
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Ladle Furnace ◽  
Flow And Heat Transfer

Effects of Pin Shape and Array Orientation on Heat Transfer and Pressure Loss in Pin Fin Arrays

1984 ◽  
Vol 106 (1) ◽  
pp. 252-257 ◽  
Author(s):  
D. E. Metzger ◽  
C. S. Fan ◽  
S. W. Haley
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Pressure Loss ◽  
Flow Direction ◽  
Circular Cross Section ◽  
Cycle Performance ◽  
Mean Flow ◽  
Pin Fin ◽  
The Mean ◽  
Cooling Air

Modern high-performance gas turbine engines operate at high turbine inlet temperatures and require internal convection cooling of many of the components exposed to the hot gas flow. Cooling air is supplied from the engine compressor at a cost to cycle performance and a design goal is to provide necessary cooling with the minimum required cooling air flow. In conjunction with this objective, two families of pin fin array geometries which have potential for improving airfoil internal cooling performance were studied experimentally. One family utilizes pins of a circular cross section with various orientations of the array with respect to the mean flow direction. The second family utilizes pins with an oblong cross section with various pin orientations with respect to the mean flow direction. Both heat transfer and pressure loss characteristics are presented. The results indicate that the use of circular pins with array orientation between staggered and inline can in some cases increase heat transfer while decreasing pressure loss. The use of elongated pins increases heat transfer, but at a high cost of increased pressure loss. In conjunction with the present measurements, previously published results were reexamined in order to estimate the magnitude of heat transfer coefficients on the pin surfaces relative to those of the endwall surfaces. The estimate indicates that the pin surface coefficients are approximately double the endwall values.

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