On this Wikipedia the language links are at the top of the page across from the article title. There are two main types of boiling: nucleate boiling where small bubbles of vapour form at discrete points, and critical heat flux boiling where the boiling surface is heated above a certain critical temperature and a film of vapor forms on the surface. Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. Boiling water is also used in boiled small potatoes recipe cooking methods including boiling, steaming, and poaching.

The lowest heat flux seen in boiling is only sufficient to cause , where the warmer fluid rises due to its slightly higher density. This condition occurs only when the superheat is very low, meaning that the hot surface near the fluid is nearly the same temperature as the boiling point. A video showing water being boiled. In general, the number of nucleation sites is increased by an increasing surface temperature. Homogeneous nucleation, where the bubbles form from the surrounding liquid instead of on a surface, can occur if the liquid is warmer in its center, and cooler at the surfaces of the container.

This can be done, for instance, in a microwave oven, which heats the water and not the container. Transition boiling may be defined as the unstable boiling, which occurs at surface temperatures between the maximum attainable in nucleate and the minimum attainable in film boiling. The formation of bubbles in a heated liquid is a complex physical process which often involves cavitation and acoustic effects, such as the broad-spectrum hiss one hears in a kettle not yet heated to the point where bubbles boil to the surface. If a surface heating the liquid is significantly hotter than the liquid then film boiling will occur, where a thin layer of vapor, which has low thermal conductivity, insulates the surface.

This condition of a vapor film insulating the surface from the liquid characterizes film boiling. Pool boiling” refers to boiling where there is no forced convective flow. Instead, the flow occurs due to density gradients. It can experience any of the regimes mentioned above. Flow boiling” occurs when the boiling fluid circulates, typically through pipes.

It’s movement can be powered by pumps, such as in power plants, or by density gradients, such as in a Thermosiphon or a heat pipe. Confined boiling refers to boiling in confined geometries, typically characterized by a that compares the gap spacing to the capillary length. The boiling point of an element at a given pressure is a characteristic attribute of the element. This is also true for many simple compounds including water and simple alcohols. Once boiling has started and provided that boiling remains stable and the pressure is constant, the temperature of the boiling liquid remains constant.

Mixtures of volatile liquids have a boiling point specific to that mixture producing vapour with a constant mix of components – the constant boiling mixture. This attribute allows mixtures of liquids to be separated or partly separated by boiling and is best known as a means of separating ethanol from water. Most types of refrigeration and some type of air-conditioning work by compressing a gas so that it becomes liquid and then allowing it to boil. This adsorbs heat from the surroundings cooling the fridge or freezer or cooling the air entering a building.

The elimination of micro-organisms by boiling follows first-order kinetics—at high temperatures, it is achieved in less time and at lower temperatures, in more time. Boiling is the method of cooking food in boiling water or other water-based liquids such as stock or milk. Pressure and a change in the composition of the liquid may alter the boiling point of the liquid. High elevation cooking generally takes longer since boiling point is a function of atmospheric pressure.