Studies on the design and parametric effects of a diode pump alkali (rubidium) laser

A computational study is conducted to explore thermal performances of natural convection hybrid fin heat sinks (HF HSs). The proposed HF HSs are a hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS). Parametric effects such as a fin spacing, an internal channel diameter, a heat dissipation on the performance of HF HSs are investigated by CFD analysis. Study results show that the thermal resistance of the HS increases while the mass-multiplied thermal resistance of the HS decreases associated with the increase of the channel diameter. The results also shows the thermal resistance of the SHF HS is 13% smaller, and the mass-multiplied thermal resistance of the HHF HS is 32% smaller compared with the pin fin heat sink (PF HS). These interesting results are mainly due to integrated effects of the mass-reduction, the surface area enhancement, and the heat pumping via the internal channel. Such better performances of HF HSs show the feasibility of alternatives to the conventional PF HS especially for passive cooling of LED lighting modules.

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Parametric Effects on the Performance of a Solid Adsorption Solar Refrigerator During Collector Cool-Down and Refrigerant Evaporation/Readsorption Phases

ASME 2007 Energy Sustainability Conference ◽

10.1115/es2007-36087 ◽

2007 ◽

Author(s):

Nnamdi V. Ogueke ◽

Emmanuel E. Anyanwu

Keyword(s):

Performance Analysis ◽

Adsorbate Concentration ◽

Parametric Effects ◽

Range Of Variation

The performance analysis of a solid adsorption solar refrigerator during the collector cool-down and refrigerant evaporation/re-adsorption phases is presented. The effects of the condenser pressure, evaporator pressure and initial adsorbate concentration on the collector cool-down and refrigerant evaporation/re-adsorption were tested. The adsorbate concentration re-adsorbed increased from 55% to 98% when the initial adsorbate concentration was dropped from 0.29kg/kg to 0.21kg/kg while the mass of ice produced rose from 0kg to 1.5kg for the same range of variation of initial adsorbate concentration.

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Application of Bifurcation Theory to Axial Flow Compressor Instability

Journal of Turbomachinery ◽

10.1115/1.3262290 ◽

1989 ◽

Vol 111 (4) ◽

pp. 426-433 ◽

Cited By ~ 44

Author(s):

F. E. McCaughan

Keyword(s):

Parameter Space ◽

Bifurcation Theory ◽

Qualitative Difference ◽

Axial Flow ◽

Complete Information ◽

Rotating Stall ◽

Numerical Work ◽

System Parameters ◽

Parametric Effects ◽

Flow Compressor

When a compression system becomes unstable, the mode of response depends on the operating and system parameters, such as throttle setting and B parameter. Previous numerical work on the model developed by Moore and Greitzer has provided a limited picture of the parametric effects. Applying bifurcation theory to a single-harmonic version of the model has supplied much more complete information, defining the boundaries of each mode of response in the parameter space. Specifically this is shown in a plot of B versus throttle setting, which compares well with the corresponding map produced experimentally. We stress the importance of the shape of the rotating stall characteristic. The analysis shows the qualitative difference between classic surge and deep surge.

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Research on Discretely Tunable Nd:YAG Ceramic Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.531.133 ◽

2012 ◽

Vol 531 ◽

pp. 133-136

Author(s):

Lei Li ◽

Xing Yu Zhang ◽

Zhao Jun Liu ◽

Qing Pu Wang ◽

Xue Bin Wan ◽

...

Keyword(s):

Pump Power ◽

Ceramic Material ◽

Nd:Yag Laser ◽

Laser Source ◽

Diode Pump ◽

Average Output

A diode-end-pumped ceramic Nd:YAG laser discretely tunable for five wavelengths was demonstrated. The tunability was obtained by a blazing grating in Littrow mode, and the laser was discretely tuned from 1052 nm to 1073 nm. Under the diode pump power of 4.59 W, the average output powers at five wavelengths were all over 1 W. The laser source may find applications in spectroscopy and metrology.

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The Air-Side Thermal-Hydraulic Performance of Flat-Tube Heat Exchangers With Louvered, Wavy, and Plain Fins Under Dry and Wet Conditions

Journal of Heat Transfer ◽

10.1115/1.3089548 ◽

2009 ◽

Vol 131 (6) ◽

Cited By ~ 23

Author(s):

Young-Gil Park ◽

Anthony M. Jacobi

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Hydraulic Performance ◽

Operating Conditions ◽

Geometrical Parameters ◽

Flat Tube ◽

Parametric Effects ◽

Dry And Wet Conditions ◽

Wet Surface ◽

Friction Performance

The air-side thermal-hydraulic performance of flat-tube aluminum heat exchangers is studied experimentally for conditions typical to air-conditioning applications, for heat exchangers constructed with serpentine louvered, wavy, and plain fins. Using a closed-loop calorimetric wind tunnel, heat transfer and pressure drop are measured at air face velocities from 0.5 m/s to 2.8 m/s for dry- and wet-surface conditions. Parametric effects related to geometry and operating conditions on heat transfer and friction performance of the heat exchangers are explored. Significant differences in the effect of geometrical parameters are found for dry and wet conditions. For the louver-fin geometry, using a combined database from the present and the previous studies, empirical curve-fits for the Colburn j- and f-factors are developed in terms of a wet-surface multiplier. The wet-surface multiplier correlations fit the present database with rms relative residuals of 21.1% and 24.4% for j and f multipliers, respectively. Alternatively, stand-alone Colburn j and f correlations give rms relative residuals of 22.7% and 29.1%, respectively.

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Thermal Analysis of the Hot Dip-Coating Process

Journal of Heat Transfer ◽

10.1115/1.2910698 ◽

1993 ◽

Vol 115 (2) ◽

pp. 453-460 ◽

Cited By ~ 8

Author(s):

Hui Zhang ◽

M. Karim Moallemi ◽

Sunil Kumar

Keyword(s):

Experimental Data ◽

Thermal Analysis ◽

Approximate Solution ◽

Dip Coating ◽

Solution Procedure ◽

Heat Diffusion ◽

Coating Process ◽

Parametric Effects ◽

Simplifying Assumptions ◽

Axial Heat

In this study a thermal analysis is performed on the hot dip-coating process where solidification of metal occurs on a bar moving through a finite molten bath. A continuum model is considered that accounts for important transport mechanisms such as axial heat diffusion, buoyancy, and shear-induced melt motion in the bath. A numerical solution procedure is developed, and its predictions are compared with those of an analytical approximate solution, as well as available experimental data. The predictions of the numerical scheme are in good agreement with the experimental data. The results of the approximate solution, however, exhibit significant disagreement with the data, which is attributed to the simplifying assumptions used in its development. Parametric effects of the bath geometry, and initial and boundary temperatures and solid velocity, as characterized by the Reynolds number, Grashof number, and Stefan numbers, are presented.

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