dc.contributor.author | Kandlikar, Satish | |
dc.date.accessioned | 2008-12-01T18:31:33Z | |
dc.date.available | 2008-12-01T18:31:33Z | |
dc.date.issued | 1992-03 | |
dc.identifier.uri | http://hdl.handle.net/1850/7564 | |
dc.description | Proceedings of the engineering foundation conference, March 22-27, 1992. | en_US |
dc.description.abstract | This paper presents the results of an experimental study of bubbles
nucleating over cavities on a localized heater surface under a flow of
subcooled water at low bubble frequencies. The experimental apparatus
consists of a rectangular flow channel 50 mm wide x 3 mm high with a
10 mm square copper heating surface placed flush in the center of the
bottom wall surface. A viewing window located directly above the
heater surface provides a clear view of the cavities and the bubbles
growing over them. A microscope equipped with a video camera is
connected to a digital image grabber board and to a video cassette
recorder. The maximum effective magnification attained is approximately
700X which allows a feature dimension recognition of 3 μm.
Water at atmospheric pressure is circulated through a constant
temperature bath equipped with heating and cooling options. The water
temperature is kept between 45 and 80°C. The flow rate through the
channel is measured by a rotameter and the flow is controlled with a
hand valve. Pressure drop through the channel is measured using an
inverted inclined U-tube manometer filled with water.
The visual study indicates that, for the flow rates investigated, the
departing bubble diameters can be as small as 5 μm over nucleating
cavities which are 2-3 μm in diameter. The departure bubble diameters
become larger as the flow rate is reduced. Experimental data is
presented for departure bubble diameter as a function of flow velocity
and cavity diameter.
Some interesting features were revealed through the visual
observation. The bubbles coming from upstream sites generally do not
knock out the bubbles growing at a nucleation site. Rather, the
oncoming bubbles follow a streamline around the nucleating bubble if
there is enough room to go around. In some cases, bubbles seem to
"walk" along the surface in the flow direction. The experiments were
conducted at relatively low heater power levels to obtain bubble
frequencies less than 500-1000 per second. | en_US |
dc.language.iso | en_US | en_US |
dc.publisher | Engineering Foundation Conference | en_US |
dc.title | Bubble behavior and departure bubble diameter of bubbles generated over nucleating cavities in flow boiling | en_US |
dc.type | Abstract | en_US |