Rising energy prices and increasingly stringent demands require efficient and environmentally friendly energy use. Nucleate boiling is the most efficient and technically manageable heat transfer mechanism. Improving heat transfer during boiling means reducing surface overheating at a given heat flux while also increasing the critical heat flux, which can be achieved by changing the micro and nanostructure and wettability of the boiling surface. The influence of the heating surface structure on heat transfer is an important parameter in the design of heaters. This work analyses the influence of surface condition of a horizontally placed and vertically oriented steel or titanium ribbon heater on the critical heat flux in saturated and subcooled boiling conditions of FC-72 and water. The influence on critical heat flux is evaluated on surfaces that are abrasion machined, etched, laser-structured or treated with thin - layer and modular porous deposits in the form of a cluster structure of 50 and 200 mm spherical copper particles. The structural surface changes of the heating surface after the achieved critical heat flux are also shown.
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