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A new computational procedure for simulating air-assist flat sprays with atomization is described and demonstrated for surface cooling applications. This procedure builds upon and utilizes findings from our previous work; particularly the integral form of the conservation equations which are used to derive explicit quadratic formulas for drop size. These formulations relate the local energetic state to initial drop size produced by primary atomization processes. In this manner, the local liquid and gas phase velocities prior to atomization are used in the quadratic formula to provide the initial drop size and the appropriate local velocities are utilized as the initial droplet momentum state in a discrete particle tracking algorithm. This procedure has been performed and compared to experimental data for drop size and velocity. This furnishes a platform to further study the effects of droplet distributions on heat transfer and momentum transfer between the spray and a heated metal surface. This approach is based on the conservation principles and generalizable, so that it can easily be implemented in any spray geometry for accurate and efficient computations of two-phase flows including spray cooling. [ABSTRACT FROM AUTHOR]

Membrane contactors are used to solve different chemical engineering tasks (e.g. water saturation with gases). Such elements are traditionally used for bubble less oxidation of blood. However, their industrial applications are rather limited by their high investment costs. This is probably the main reason why membrane contactors are not used so widely, e.g. classical absorbers, etc. If potted bundles of hollow fibres are available, then it is a relatively simple task to design an ad hoc membrane contactor. However, it must be emphasised that to achieve the highest mass transfer efficiency requires a rather time-consuming tuning of each ad hoc designed contactor. To check the differences by water evaporation were aligned two modes, the water inside the hollow fibre membrane and fan air outside, next with the water outsides and flowing pressure air inside the membrane.

The general term "spray cooling" is for the research presented here limited to the spray cooling of hot surfaces with film boiling, starting at temperatures of about 1200 °C and finishing at the Leidenfrost point where cooling intensity changes rapidly. This is typical area of secondary cooling in continuous casting. Herein, a correlation for Heat Transfer Coefficient (HTC). The most frequently used parameter of water impingement density is in the presented correlation used together with impact pressure to get good results. This study uses both water and mist nozzles. It is shown and experimentally verified why equations based only on the water impingement density cannot provide sufficiently precise predictions of HTC. [ABSTRACT FROM AUTHOR]

A basic energy balance that includes phase change has been used to describe the boiling heat transfer process. By using the differential form of this energy balance, the relative change in the heat transfer coefficient can be determined when the surface and coolant temperature change. This represents a general solution to the boiling heat transfer problem under high flux conditions where fully mixed thermal boundary layer exists, although the solution procedure is approximate. The results agree quite well with experimental data. Further work remains to prescribe the heat transfer process near the critical heat flux and Leidenfrost point. This approach vastly reduces the empiricism and data required for boiling heat transfer processes, and also existing data can be used to generalize to a wide range of conditions. [ABSTRACT FROM AUTHOR]