Experimental Investigations for Fluid Flow Characteristics of Refrigerant R134a in a Microtubes Evaporator

A series of experimental investigations with a stringent measurement method on the fluid flow characteristics of slot jet without or with a target surface have been successfully conducted. From all the fluid velocity data measured in the present study, the experimental conditions have been verified to be spanwise-symmetrically maintained and the results have been achieved in a spanwise-symmetric form. Three types of jet configuration without or with target surface are investigated: (A) Confined Slot Jet without Target Surfaces – the fluid flow parameters studied in the present investigation is the jet Reynolds number (ReD). Its ranges are ReD=506-1517. (B) Confined Slot Jet with Smooth Surfaces – the fluid flow parameters studied in the present investigation include the ratio of jet separation distance (H) to nozzle width (W) and the jet Reynolds number (ReD). The ranges of the relevant parameters are H/W=2–10 and ReD=504–1526. (C) Confined Slot Jet with Extended Surfaces – the fluid flow parameters studied include the ratio of jet separation distance (H) to nozzle width (W), the Reynolds number (ReD) and the ratio of extended surface height (Hes) to nozzle width (W). Their ranges are H/W=3–10, Hes/W=0.74-3.40 and ReD=501–1547. The flow characteristics such as the local mean streamwise velocity distribution, mean streamwise velocity decay along jet centerline, local jet turbulence intensity distribution, and turbulence intensities along jet centerline have been presented and discussed in the study.

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Experimental Investigation on Flow Characteristics of Supercritical CO2 in a Helically Coiled Tube

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.631 ◽

2013 ◽

Vol 368-370 ◽

pp. 631-635

Author(s):

Shu Xiang Wang ◽

Wei Zhang ◽

Jin Liang Xu

Keyword(s):

Heat Flux ◽

Fluid Flow ◽

Mass Flux ◽

Flow Characteristics ◽

Experimental Investigations ◽

Coiled Tube ◽

Frictional Pressure Drop ◽

Helically Coiled Tube ◽

Coil Diameter ◽

Fluid Flow Characteristics

Under the background of global warming, carbon dioxide among natural refrigerants has attracted considerable attention as an alternative refrigerant. In the present study, experimental investigations of the fluid flow characteristic of supercritical CO2in a helically coiled tube with the inner diameter 9.0 mm, coil diameter 283 mm and coil pitch 32 mm were carried out. Both frictional pressure drop and friction factor were obtained under the pressure of 8.0 MPa, mass flux from 0 to 600 kg/m2s and inner heat flux from 0 to 20 kW/m2. The results indicate that inner wall heat flux and mass flux had significant effects on fluid flow characteristics. The study provides experimental data that could be used for the design and development of more efficient exchangers for refrigeration conditioning, heat pump and some other systems.

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Fluid Flow Characteristics for Partially-Confined Compact Plain-Plate-Fin Heat Sinks

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72225 ◽

2005 ◽

Cited By ~ 2

Author(s):

M. P. Wang ◽

T. Y. Wu ◽

J. T. Horng ◽

C. Y. Lee ◽

Y. H. Hung

Keyword(s):

Experimental Data ◽

Fluid Flow ◽

Pressure Drop ◽

Heat Sink ◽

Flow Behavior ◽

Flow Characteristics ◽

Heat Sinks ◽

Experimental Investigations ◽

Channel Height ◽

Fluid Flow Characteristics

A series of experimental investigations with a stringent measurement method on the study of the fluid flow behavior for confined compact heat sinks in forced convection have been successfully conducted. In the present study, a theoretical model to effectively predict the velocity and pressure drop for partially-confined heat sinks has been successfully developed. The air velocities flowing into heat sink Us through side bypass U1 and top bypass U2 for various 0.47<H/Hc<1 ratios are evaluated, where H/Hc is the ratio of the heat sink height to channel height. The maximum and average deviations of the velocities predicted by the present model from the experimental data are less than 20.31% and 13.13%, respectively, for confined compact heat sinks. Besides, the results show a good agreement between the predicted results and the experimental data of the pressure drop for the cases of H/Hc = 1. Nevertheless, the relative deviation of the predictions from the experimental data becomes more significant with decreasing H/Hc ratio, i.e., increasing the top bypass of confined compact heat sink. A new modified correlation of pressure drop including the H/Hc effect is presented. The maximum and average deviations of the results predicted by the new correlation from the experimental data are 14.48% and 7.72%, respectively.

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Flow and Heat Transfer Characteristics of Supercritical Nitrogen in Mini-Tube

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82072 ◽

2009 ◽

Author(s):

P. Zhang ◽

Y. Huang ◽

R. Z. Wang

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Flow Characteristics ◽

Influential Factors ◽

Experimental Investigations ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Flow And Heat Transfer ◽

Liquid Phases ◽

Fluid Flow Characteristics

Fluids with the state near the critical points-supercritical fluids show many tremendously strange characteristics, such as singularities in compressibility and viscosity, diminishing difference in vapor and liquid phases and so on which have attracted a lot of investigations both experimentally and theoretically for fundamental research. In the present study, experimental investigations of the heat transfer and fluid flow characteristics of supercritical nitrogen in a mini-tube of 2 mm in diameter and 250 mm in length are carried out, the effects of many influential factors on fluid flow and heat transfer are studied. Meanwhile, the numerical analysis of the fluid flow and heat transfer characteristics of supercritical nitrogen is also conducted by using FLUENT. It is found that the agreement between the experimental and numerical results is quite good and the further interpretation and discussion are carried out.

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