[4290] Artykuł: Pool and flow boiling on surfaces with micro-cavitiesCzasopismo: Proceedings of Int. Conf. Heat transfer and renewable sources of energy 2014 Strony: 259-266Opublikowano: 2014 Autorzy / Redaktorzy / Twórcy
Grupa MNiSW: Pozostałe publikacje (niepunktowane) Punkty MNiSW: 0 | ||||||||||||||||||||
The experimental studies presented here focused on pool and flow boiling heat transfer on plain surfaces and surfaces with micro-cavities. The heating surfaces were prepared by electrical discharge machining (EDM). In studies on pool boiling the surfaces fabricated from copper were used; the experiments were carried out for water, ethanol, fluorinert FC-72 and Novec 649 at atmospheric pressure. Structures with micro-cavities showed the highest boiling heat transfer coefficient improvement for FC-72 – up to 300% in comparison to a plain copper surface. Flow boiling research concerned FC-72 flowing through a horizontally positioned mini-channel when its bottom wall is heated. It is the thin foil made of Haynes-230 alloy. These experiments were carried out under a pressure slightly higher than the atmospheric one. Comparison of results for flow and pool boiling indicates that obtained heat transfer coefficients are a few times higher for pool boiling than for flow boiling in the boiling incipience conditions. There are basic differences in the local heat transfer coefficient values during the development of flow boiling in a mini-channel, depending on the location along the flow in the channel. In developed flow boiling, high heat transfer coefficients were obtained, but they decreased when the share of vapor in the liquid-vapor mixture rises.
