scholarly journals A pressure drop correlation for low Reynolds number Newtonian flows through a rectangular orifice in a similarly shaped micro-channel

2013 ◽  
Vol 91 (1) ◽  
pp. 1-6 ◽  
Author(s):  
V. Zivkovic ◽  
P. Zerna ◽  
Z.T. Alwahabi ◽  
M.J. Biggs
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Low Reynolds Number ◽  
Micro Channel ◽  
Newtonian Flows ◽  
Low Reynolds

scholarly journals Effect of Pin Diameter Degressive Gradient on Heat Transfer in a Microreactor with Non-Uniform Pin-Fin Array under Low Reynolds Number Conditions

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2702
Author(s):  
Miao Qian ◽  
Jie Li ◽  
Zhong Xiang ◽  
Chao Yan ◽  
Xudong Hu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Low Reynolds Number ◽  
Hydrodynamic Characteristics ◽  
Pin Fin ◽  
Low Reynolds ◽  
Pin Fin Array

To improve the efficiency of hydrogen-producing microreactors with non-uniform pin-fin array, the influence of the pin diameter degressive gradient of the non-uniform pin-fin array (NPFA) on heat transfer and pressure drop characteristics is analyzed in this study via numerical simulation under low Reynolds number conditions. Because correlations in prior studies cannot be used to predict the Nusselt number and pressure drop in the NPFA, new heat transfer and friction factor correlations are developed in this paper to account for the effect of the pin diameter degressive gradient, providing a method for the optimized design of the pin diameter degressive gradient for a microreactor with NPFA. The results show that the Nusselt number and friction factor under a low Reynolds number are quite sensitive to the pin diameter degressive gradient. Based on the new correlations, the exponents of the pin diameter degressive gradient for the friction factor and Nusselt number were 6.9 and 2.1, respectively, indicating the significant influence of the pin diameter degressive gradient on the thermal and hydrodynamic characteristics in the NPFA structure.

scholarly journals Investigation of effect on cross-flow heat exchanger with air flow non-uniformity under low Reynolds number

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770808 ◽  
Author(s):  
Kai Shen ◽  
Zhendong Zhang ◽  
Ziqing Zhang ◽  
Youwen Yang
Keyword(s):  
Reynolds Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Low Reynolds Number ◽  
Air Flow ◽  
Cross Flow ◽  
Calculation Model ◽  
Flow Heat ◽  
Air Flows ◽  
Low Reynolds

In this study, the theoretical and experimental study of a cross-flow heat exchanger is carried out based on the theory of porous media under low Reynolds number. The accuracy of the mathematical calculation model is verified by experiments. Pressure drop in air side and efficiency of heat exchanger are analyzed with mathematical models of various non-uniform air flows under low Reynolds number. The responses are found influences of air flow non-uniformity on pressure drop and efficiency of heat exchanger have certain rules. The difference in pressure drops between non-uniform air flows and evenly distributed air flows is linearly related to variance [Formula: see text] of non-uniformity. And the increasing rate of resistance energy consumption difference between non-uniform air flows and evenly distributed air flows is approximately linearly related to the relatively non-uniform coefficient squared [Formula: see text] of non-uniformity. The descent range of heat transfer efficiency has exponential relation to the relatively non-uniform coefficient [Formula: see text].

Pressure Drop for Low Reynolds-Number Flows Through Regular and Random Screens

2009 ◽  
Vol 80 (2) ◽  
pp. 193-208 ◽  
Author(s):  
A. Valli ◽  
J. Hyväluoma ◽  
A. Jäsberg ◽  
A. Koponen ◽  
J. Timonen
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Low Reynolds Number ◽  
Low Reynolds Number Flows ◽  
Low Reynolds ◽  
Reynolds Number Flows

Low Reynolds Number Flow in Spiral Microchannels

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Denis Lepchev ◽  
Daniel Weihs
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Stokes Equations ◽  
Low Reynolds Number ◽  
Creeping Flow ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Contraction Parameter ◽  
Number Flow ◽  
Low Reynolds

We study the creeping flow of an incompressible fluid in spiral microchannels such as that used in DNA identifying “lab-on-a-chip” installations. The equations of motion for incompressible, time-independent flow are developed in a three-dimensional orthogonal curvilinear spiral coordinate system where two of the dimensions are orthogonal spirals. The small size of the channels results in a low Reynolds number flow in the system, which reduces the Navier–Stokes set of equations to the Stokes equations for creeping flow. We obtain analytical solutions of the Stokes equations that calculate velocity profiles and pressure drop in several practical configurations of channels. Both pressure and velocity have exponential dependence on the expansion/contraction parameter and on the streamwise position along the channel. In both expanding and converging channels, the pressure drop is increased when the expansion/contraction parameter k and/or the curvature is increased.

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