scholarly journals Thermal Performance Analysis and Empirical Correlations for Laminar Forced Convection over 30° V-Baffled Square Channel

2014 ◽  
Vol 6 ◽  
pp. 930272 ◽  
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai
Keyword(s):  
Heat Transfer ◽  
Performance Analysis ◽  
Forced Convection ◽  
Thermal Performance ◽  
Flow Direction ◽  
Periodic Flow ◽  
Square Channel ◽  
Flow And Heat Transfer ◽  
Flow Configurations ◽  
Laminar Forced Convection

Thermal performance analysis for laminar forced convection in an isothermal wall square channel with 30° V-baffle is presented numerically. The parameters of the V-baffle, blockage ratio (b/H, BR), pitch ratio (P/H, PR), flow direction (V-Downstream and V-Upstream), and arrangement (in-line and staggered), are studied and compared with the previous works, 20° and 45° V-baffle. The Reynolds number based on the hydraulic diameter of the channel ( D h), Re = 100–2000, is used in range study. The results show that the flow configurations of 30° V-baffle are found similar as 20° and 45° V-baffle. The fully developed periodic flow and heat transfer are created around 7th-8th module, while the periodic flow and heat transfer profiles are found at 2nd module in all cases. Except for the periodic concept, the 30° V-baffle can help to reduce the pressure loss around 2.3 times in comparison with the 45° V-baffle at the maximum f/ f0 value (BR = 0.3, PR = 1, V-Downstream). The optimum thermal enhancement factor for the 30° V-baffle is found around 4.25 at BR = 0.15, PR = 1, and Re = 2000 for V-Downstream case with in-line arrangement.

Heat Transfer and Pressure Drop in a Rotating Two-Pass Square Channel With Different Ribs at High Rotation Numbers

2015 ◽  
Author(s):  
Yang Li ◽  
Hongwu Deng ◽  
Guoqiang Xu ◽  
Shuqing Tian
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Flow Direction ◽  
Moderate Pressure ◽  
Transfer Coefficients ◽  
Square Channel ◽  
Smooth Case ◽  
Rib Turbulators

Rotation effects on heat transfer and pressure drop in a rotating two-pass square channel with ribs is experimentally investigated. The cooper plate heating technique is applied to obtain the regional average heat transfer coefficients. The Reynolds number and rotation number varies from 10000 to 60000, and 0 to 2.0, respectively. Rib turbulators are placed on the leading and trailing walls of the channel at an angle of 90 deg or 45 deg to the flow direction. The rib pitch-to-height (P/e) ratio is 10 and the height-to-hydraulic diameter (e/Dh) ratio is 0.1 for all tests. The detailed comparisons between smooth wall case and ribbed wall cases are presented. At stationary, increasing the Reynolds number decreases heat transfer and thermal performance ratios, but raises the friction factor ratios dramatically. Rotation shows the strongest effect on heat transfer in smooth case, and then 90 deg rib case, and the least in 45 deg rib case. Channel friction in smooth case is increased by rotation monotonously, but decreases with Ro in ribbed case when Ro increases up to 0.5. The similar thermal performances trends are observed for smooth and ribbed cases at rotation but with different peak point. The 45 deg rib channel has the superior thermal performance because it incurs the highest heat transfer and moderate pressure penalty.

Numerical Simulation of the Effect of Rib Orientation on Fluid Flow and Heat Transfer in Rotating Serpentine Passages

2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Berrabah Brahim
Keyword(s):  
Heat Transfer ◽  
Flow Direction ◽  
Density Ratio ◽  
Reynolds Stress Model ◽  
Secondary Flows ◽  
First Passage ◽  
Square Channel ◽  
The Third ◽  
Flow And Heat Transfer ◽  
First Case

The effect of rib orientation on flow and heat transfer in a four-pass square channel with skewed ribs in nonorthogonal-mode rotation was numerically studied by using omega-based Reynolds stress model (SMC−ω). Two cases are examined: in first case, the ribs are oriented with respect to the main flow direction at an angle of −45 deg in the first and third passage and at an angle of +45 deg in the second passage. The second case is identical to the first case with the ribs oriented at angle of +45 deg in the three passages. The calculations are carried out for a Reynolds number of 25,000, a rotation number of 0.24, and a density ratio of 0.13. The results show that the secondary flows induced by −45 deg ribs and by rotation combine partially destructively in the first and third passage of first case. In contrast, for second case, the secondary flows induced by +45 deg ribs and by rotation combine constructively in the first passage, while the flow is dominated by the vortices induced by +45 deg ribs in the third passage. In first case, a significant degradation of the heat transfer rate is observed on the coleading side of the first passage and on both cotrailing and coleading sides of the third as compared to second case. Consequently, the rib orientations at +45 deg are preferred in the radial outward flowing passage with an acceptable pressure drop. The numerical results are in agreement with the available experimental data.

scholarly journals Flow and Heat Transfer of Laminar Forced Convection in Arbitrary Polygonal Ducts

1973 ◽  
Vol 37 (4) ◽  
pp. 385-390,a1
Author(s):  
Setsuro Hiraoka ◽  
Ikuho Yamada ◽  
Hajime Nakamura
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow And Heat Transfer ◽  
Laminar Forced Convection
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