Search results
Results from the WOW.Com Content Network
Superheating can occur when an undisturbed container of water is heated in a microwave oven. At the time the container is removed, the lack of nucleation sites prevents boiling, leaving the surface calm. However, once the water is disturbed, some of it violently flashes to steam, potentially spraying boiling water out of the container. [6]
Pressure cookers produce superheated water, which cooks the food more rapidly than boiling water. Superheated water is liquid water under pressure at temperatures between the usual boiling point, 100 °C (212 °F) and the critical temperature, 374 °C (705 °F). [citation needed] It is also known as "subcritical water" or "pressurized hot water".
Rolling boil of water in an electric kettle. Boiling or ebullition is the rapid phase transition from liquid to gas or vapour; the reverse of boiling is condensation.Boiling occurs when a liquid is heated to its boiling point, so that the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.
Departure from nucleate boiling (DNB) occurs in sub-cooled flows and bubbly flow regimes. DNB happens when many bubbles near the heated surface coalesce and impede the ability of local liquid to reach the surface. The mass of vapor between the heated surface and local liquid may be referred to as a vapor blanket. Dryout
Leidenfrost droplet Demonstration of the Leidenfrost effect Leidenfrost effect of a single drop of water. The Leidenfrost effect is a physical phenomenon in which a liquid, close to a solid surface of another body that is significantly hotter than the liquid's boiling point, produces an insulating vapor layer that keeps the liquid from boiling rapidly.
For a visual experience of natural convection, a glass filled with hot water and some red food dye may be placed inside a fish tank with cold, clear water. The convection currents of the red liquid may be seen to rise and fall in different regions, then eventually settle, illustrating the process as heat gradients are dissipated.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Heat transfer by thermal radiation may be minimized by silvering flask surfaces facing the gap but can become problematic if the flask's contents or surroundings are very hot; hence vacuum flasks usually hold contents below the boiling point of water. Most heat transfer occurs through the neck and opening of the flask, where there is no vacuum.