Testing of an R134a Spray Evaporative Heat Sink

Althausen, D.; Golliher, Eric

doi:10.4271/2008-01-2165

Cited by 7 publications

(2 citation statements)

References 6 publications

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“…Because of the low natural pressures in the areas where it is utilized, flash vaporization technology has attracted a lot of interest, especially in aircraft applications. Agencies such as NASA have identified compact flash evaporator system as one of the alternative methods of heat dissipation for the crew exploration vehicle thermal control system [6][7][8].…”

Section: Extended Abstractmentioning

confidence: 99%

Experimental Study of the Cooling Properties in Low-Pressure Flash Evaporation

Quan,

Chai,

Yin

et al. 2024

Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer

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Section: Extended Abstractmentioning

confidence: 99%

Experimental Study of the Cooling Properties in Low-Pressure Flash Evaporation

Quan,

Chai,

Yin

et al. 2024

Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer

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“…To maximize the heat transfer that takes place after impingement with the heated surface, it is desirable to have the largest Weber number possible without splashing occurring. This allows the crater that was formed by the droplet to cover the largest amount of surface area without losing any of the droplet volume to crown formation or secondary atomization, thus maximizing the possible heat transfer of each droplet (Althausen and Golliher, 2008).…”

Section: Chapter 1 : Introductionmentioning

confidence: 99%

Spray cooling simulation implementing time scale analysis and the Monte Carlo method

Kreitzer¹

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Spray Cooling Simulation Implementing TimeScale Analysis and the Monte Carlo Method PAUL JOSEPH KREITZER Spray cooling research is advancing the field of heat transfer and heat rejection in high power electronics. Smaller and more capable electronics packages are producing higher amounts of waste heat, along with smaller external surface areas, and the use of active cooling is becoming a necessity. Spray cooling has shown extremely high levels of heat rejection, of up to 1000 W/cm 2 using water. Simulations of spray cooling are becoming more realistic, but this comes at a price. A previous researcher has used CFD to successfully model a single 3D droplet impact into a liquid film using the level set method. However, the complicated multiphysics occurring during spray impingement and surface interactions increases computation time to more than 30 days. Parallel processing on a 32 processor system has reduced this time tremendously, but still requires more than a day. The present work uses experimental and computational results in addition to numerical correlations representing the physics occurring on a heated impingement surface. The current model represents the spray behavior of a Spraying Systems FullJet 1/8-g spray nozzle. Typical spray characteristics are indicated as follows: flow rate of 1.05x10-5 m 3 /s, normal droplet velocity of 12 m/s, droplet Sauter mean diameter of 48 µm, and heat flux values ranging from approximately 50-100 W/cm 2. This produces non-dimensional numbers of: We 300-1350, Re 750-3500, Oh 0.01-0.025. Numerical and experimental correlations have been identified representing crater formation, splashing, film thickness, droplet size, and spatial flux distributions. A combination of these methods has resulted in a Monte Carlo spray impingement simulation model capable of simulating hundreds of thousands of droplet impingements or approximately one millisecond. A random sequence of droplet impingement locations and diameters is generated, with the proper radial spatial distribution and diameter distribution. Hence the impingement, lifetime and interactions of the droplet impact craters are tracked versus time within the limitations of the current model. A comparison of results from this code to experimental results shows similar trends in surface behavior and heat transfer values. Three methods have been used to directly compare the simulation results with published experimental data, including: contact line length estimates, empirical heat transfer equation calculations, and nondimensional Nusselt numbers. A Nusselt number of 55.5 was calculated for experimental values, while a Nu of 16.0 was calculated from the simulation.

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