Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.

Assessment of high-heat-flux thermal management schemes

Spray cooling heat transfer: The state of the art

Advances and challenges in explaining fuel spray impingement: How much of single droplet impact research is useful?

Review of spray cooling – Part 1: Single-phase and nucleate boiling regimes, and critical heat flux

https://engineering.purdue.edu/BTPFL/BTPFL%20Publications/56.pdf

Correlation of sauter mean diameter and critical heat flux for spray cooling of small surfaces

Spray cooling of a hot surface was investigated to ascertain the effect of nozzle-to-surface distance on critical heat flux (CHF). Full cone sprays of Fluorinert FC-72 and FC-87 were used to cool a 12.7 X 12.7 mm 2 surface. A theoretical model was constructed that accurately predicts the spray's volumetric flux (liquid volume per unit area per unit time) distribution across the heater surface. Several experimental spray sampling techniques were devised to validate this model. The impact of volumetric flux distribution on CHF was investigated experimentally. By measuring CHFfor the same nozzle flow rate at different nozzle-to-surface distances, it was determined CHF can be maximized when the spray is configured such that the spray impact area just inscribes the square surface of the heater. Using this optimum configuration, CHF data were measured over broad ranges of flow rate and subcooling, resulting in a new correlation for spray cooling of small surfaces.

Optimizing and Predicting CHF in Spray Cooling of a Square Surface

The performances of free jets and sprays were compared experimentally in cooling a 12.7 × 12.7 mm 2 chip in order to ascertain the effects of key parameters on cooling performance and to develop correlations ,for critical heat flux (CHF) which are applicable to dielectric coolants. Increasing liquid flow rate and subcooling increased CHF for both cooling schemes. At high subcooling, comparable CHF values were attained with both for equal flow rates. However, spray cooling produced much greater CHF at low subcooling than did jet cooling. This phenomenon was found to be closely related to the hydrodynamic structure of the liquid film deposited upon the chip surface. In jet cooling, the film (wall jet), being anchored to the surface only at the impingement zone, was separated from the surface during vigorous boiling due to the momentum of vapor normal to the surface. The individual spray drops were more effective at securing liquid film contact with the surface at low subcooling, which delayed CHF relative to jet cooling with the same flow rate. This paper also discusses practical concerns associated with implementation of each cooling scheme including system reliability and the risk associated with premature CHF during chip power transients.

Kurt A. Estes

Papers

Correlation of sauter mean diameter and critical heat flux for spray cooling of small surfaces

Optimizing and Predicting CHF in Spray Cooling of a Square Surface

Comparison of Two-Phase Electronic Cooling Using Free Jets and Sprays