Study of the heat transfer and of the hydraulic resistance associated with the flow of air through narrow rectangular channels

1972 ◽  
Vol 22 (3) ◽  
pp. 315-318 ◽  
Author(s):  
P. A. Novikov ◽  
L. A. Shcherbakov
Keyword(s):  
Heat Transfer ◽  
Hydraulic Resistance ◽  
Rectangular Channels

A Numerical Study of Flow and Heat Transfer in Rotating Rectangular Channels AR=4 With 45 deg Rib Turbulators by Reynolds Stress Turbulence Model

2003 ◽  
Vol 125 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Mohammad Al-Qahtani ◽  
Hamn-Ching Chen ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Density Ratio ◽  
Convective Transport ◽  
High Density ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Rectangular Channels ◽  
Density Ratios

Computations were performed to study three-dimensional turbulent flow and heat transfer in stationary and rotating 45 deg ribbed rectangular channels for which experimental heat transfer data were available. The channel aspect ratio (AR) is 4:1, the rib height-to-hydraulic diameter ratio e/Dh is 0.078 and the rib-pitch-to-height ratio P/e is 10. The rotation number and inlet coolant-to-wall density ratios, Δρ/ρ, were varied from 0.0 to 0.28 and from 0.122 to 0.40, respectively, while the Reynolds number was fixed at 10,000. Also, two channel orientations (β=90deg and 135 deg from the rotation direction) were investigated with focus on the high rotation and high density ratios effects on the heat transfer characteristics of the 135 deg orientation. These results show that, for high rotation and high density ratio, the rotation induced secondary flow overpowered the rib induced secondary flow and thus change significantly the heat transfer characteristics compared to the low rotation low density ratio case. A multi-block Reynolds-Averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure. In the present method, the convective transport equations for momentum, energy, and turbulence quantities are solved in curvilinear, body-fitted coordinates using the finite-analytic method.

Experimental Investigation of Heat Transfer in Impingement Air Cooled Plate Fin Heat Sinks

2005 ◽  
Vol 128 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Transfer Model ◽  
Heat Sinks ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Developing Flow ◽  
Rectangular Channels

Impingement cooling of plate fin heat sinks is examined. Experimental measurements of thermal performance were performed with four heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The percent uncertainty in the measured thermal resistance was a maximum of 2.6% in the validation tests. Using a simple thermal resistance model based on developing laminar flow in rectangular channels, the actual mean heat transfer coefficients are obtained in order to develop a simple heat transfer model for the impingement plate fin heat sink system. The experimental results are combined into a dimensionless correlation for channel average Nusselt number Nu∼f(L*,Pr). We use a dimensionless thermal developing flow length, L*=(L∕2)∕(DhRePr), as the independent parameter. Results show that Nu∼1∕L*, similar to developing flow in parallel channels. The heat transfer model covers the practical operating range of most heat sinks, 0.01<L*<0.18. The accuracy of the heat transfer model was found to be within 11% of the experimental data taken on four heat sinks and other experimental data from the published literature at channel Reynolds numbers less than 1200. The proposed heat transfer model may be used to predict the thermal performance of impingement air cooled plate fin heat sinks for design purposes.

Heat Transfer and Pressure Drop for Flow Boiling of Water in Narrow Vertical Rectangular Channels

2003 ◽  
Author(s):  
Jianyun Shuai ◽  
Rudi Kulenovic ◽  
Manfred Groll
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
High Heat ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Heat Fluxes ◽  
Experimental Conditions ◽  
Rectangular Channels

Flow boiling in small-sized channels attracted extensive investigations in the past two decades due to special requirements for transfer of high heat fluxes from narrow spaces in various industrial applications. Experiments on various aspects of flow boiling in narrow channels were carried out and theoretical attempts were undertaken. But these investigations showed large differences, e.g. up till now the knowledge on the development of flow patterns in small non-circular flow passages is very limited. This paper deals with investigations on flow boiling of water in two rectangular channels with dimensions (width×depth) 2.0×4.0 mm2 and 0.5×2.0 mm2 (corresponding hydraulic diameters are 2.67 mm and 0.8 mm). The pressure at the test section exit is atmospheric. For steady-state experimental conditions the effects of heat flux, mass flux and inlet subcooling on the boiling heat transfer coefficient and the pressure drop are investigated. Flow patterns and the transition of flow patterns along the channel axis are visualized and documented with a video-camera. Bubbly flow, slug flow and annular flow are distinguished in both channels. Preliminary flow pattern maps are generated.

DEFINITION OF HYDRAULIC RESISTANCE OF UNDERGROUND OIL PIPELINE

2020 ◽  
Vol 69 (1) ◽  
pp. 56-61
Author(s):  
L. Yermekkyzy ◽  
Keyword(s):  
Heat Transfer ◽  
Inverse Problem ◽  
Numerical Method ◽  
Hydraulic Resistance ◽  
High Viscosity ◽  
System Of Equations ◽  
Oil Viscosity ◽  
Oil Pipeline ◽  
Conservation Of Momentum ◽  
Definition Of

The results of solving the inverse problem of determining the hydraulic resistance of a main oil pipeline are presented. The formulation of the inverse problem is formulated, a numerical method for solving the system of equations is described. The hydraulic resistance of the pipeline during the "hot" pumping of high-curing and high-viscosity oil changes during operation. Oil temperature decreases along the length of the pipeline due to heat transfer from the soil, leading to an increase in oil viscosity and an increase in hydraulic resistance.The dependence of the hydraulic resistance of the pipeline on the parameters of oil pumping is determined by solving the inverse problem. The inverse problem statement consists of a system of equations of laws of conservation of momentum, mass, energy and hydraulic resistance in the form of Altshul with unknown coefficients. The system of partial differential equations of hyperbolic type for speed and pressure is solved by the numerical method of characteristics, and the heat transfer equations by the iterative method of running counting.

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