Friction Losses and Heat Transfer in Laminar Microchannel Single-Phase Liquid Flow

Author(s):  
Vaˆnia Silve´rio ◽  
Anto´nio L. N. Moreira

Many studies addressed the validity of macroscale theories to describe momentum and heat transfer in single phase in microtubes, but the results are often inconsistent. It is suggested that the fluid flow and heat transfer in microchannels without phase change is substantially different from that in larger channels. However, these discrepancies may be attributed to experimental uncertainties mainly due to the use of conventional measurement apparatus that are too big to implement in the tested system. Other researchers explain the microfluidic behavior with the ratio of surface forces to body forces which evolve inversely to the hydraulic diameter. The present work considers the use of a dedicated experimental facility built to allow the use of optical diagnostic and flow visualization techniques in heated microtubes and addresses the potential microscale effects which may arise for single phase flow conditions. The experiments encompass measurements of the pressure drop and the longitudinal temperature distribution in the fully developed single phase liquid flow established in circular and square cross section of channels made of borosilicate glass with hydraulic diameters from 50μm up to 500μm. The flow conditions consider a range of Reynolds number from 10 up to around 2500 and the use of diverse fluids to account for the effects of liquid properties. Namely, three distinct fluids were used: distilled water, methoxy-nonafluorobutane and methanol. For heat transfer studies, the channels are heated with constant wall heat flux supplied by Joule effect by means of external wall rf-PERTE deposition of Indium Oxide thin film. The thin transparent film showed good chemical stability in the range of temperatures up to 70°C, therefore indicating that the thermal boundary condition approximates a constant wall heat flux condition. The mass flux is varied from 60 to 3300kg.m−2·s−1 and the heat flux was set between 4 and 6kW.m−2. Experimental uncertainties are estimated to be below 14% for the friction factor and below 24% for Nusselt number; the former is dominated by inaccuracies in the diameter, while the second is dominated by temperature measurements.

1998 ◽  
Vol 120 (1) ◽  
pp. 152-159 ◽  
Author(s):  
H. Kumamaru ◽  
Y. Fujiwara

An annular two-phase flow model has been proposed to predict the pressure drop and heat transfer of magnetohydrodynamic (MHD) gas-liquid metal two-phase flow in a rectangular channel for the case of high void fraction. The model for a rectangular channel, in which the applied magnetic field is perpendicular to the short side of the channel cross-section, nearly predicts Inoue et al.’s experimental data on the MHD pressure drop. For fusion reactor conditions, the model shows calculated results that the MHD pressure drop for two-phase flow can be lowered to 10 percent of that of the single-phase liquid flow and the heat transfer coefficient can be increased by a factor of two or more over that of the single-phase liquid flow.


Author(s):  
Jeffrey L. Perry ◽  
Satish G. Kandlikar

The topic of single phase liquid flow in submicron or nanochannels is a nascent field. There have only been a couple papers that have dealt with this area directly. The most probable reason for this is that currently most research in fluid mechanics or heat transfer is being focused on micron size channels. To help facilitate researchers to focus on this undeveloped area, this paper serves as a review for some of the micro-fabrication processes that will make it possible for engineers and scientists to study this field in greater detail.


2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ted D. Bennett

The historical approach to averaging the convection coefficient in tubes of constant wall heat flux leads to quantitative errors in short tubes as high as 12.5% for convection into fully developed flows and 33.3% for convection into hydrodynamically developing flows. This mistake can be found in teaching texts and monographs on heat transfer, as well as in major handbooks. Using the correctly defined relationship between local and average convection coefficients, eight new correlations are presented for fully developed and developing flows in round tubes and between parallel plates for the constant wall heat flux condition. These new correlations are within 2% of exact solutions for fully developed flows and within 6% of first principle calculations for hydrodynamically developing flows.


2000 ◽  
Vol 123 (2) ◽  
pp. 119-126 ◽  
Author(s):  
Weipeng Jiang ◽  
Cem Sarica ◽  
Erdal Ozkan ◽  
Mohan Kelkar

The fluids in horizontal wells can exhibit complicated flow behaviors, in part due to interaction between the main flow and the influxes along the wellbore, and due to completion geometries. An existing small-scale test facility at Tulsa University Fluid Flow Projects (TUFFP) was used to simulate the flow in a horizontal well completed with either circular perforations or slotted liners. Single phase liquid flow experiments were conducted with Reynolds numbers ranging approximately from 5000 to 65,000 and influx to main flow rate ratios ranging from 1/50 to 1/1000. For both the perforation and slot cases, three different completion densities and three different completion phasings are considered. Based on the experimental data, new friction factor correlations for horizontal well with multiple perforation completion or multiple slots completion were developed using the principles of conservation of mass and momentum.


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