boiling

boiling frog

A problematic situation that will gradually increase in severity until it reaches calamitous proportions, such that the people involved or affected by it will not notice the danger until it is too late to act. It is a metaphor taken from an anecdotal parable about boiling a frog, in which a frog placed in boiling water will immediately try to save itself, but one placed in cool water that is gradually brought to a boil will not notice the heat until it is boiled to death. Drug addiction is often a boiling frog, as many people don't see their addiction as problematic until it has consumed their lives.See also: boiling, frog

boiling frog syndrome

The failure to accept, acknowledge, or act against a problematic situation that will gradually increase in severity until it reaches calamitous proportions. It is a metaphor taken from an anecdotal parable about boiling a frog, in which a frog placed in boiling water will immediately try to save itself, but one placed in cool water that is gradually brought to a boil will not notice the heat until it is boiled to death. Many environmentalists accuse naysayers of having boiling frog syndrome, not accepting that damage is being done until the earth is polluted beyond repair.See also: boiling, frog, syndrome

boiling hot

Of an object, the weather, or a living creature, having an extremely hot temperature. The phrase is an often hyperbolic reference to the boiling point of liquids. I hate July in this part of the country, it's boiling hot down here. Your forehead is boiling hot! I'm taking you to see a doctor.See also: boiling, hot

boiling mad

Furious; extremely angry. The phrase refers to one's "blood boiling," meaning the same thing. John's views were so ignorant and narrow-minded that I was boiling mad after talking to him.See also: boiling, mad

boiling point

1. One's limit in patience, temper, or equanimity, after which one loses control of one's emotions. Likened to the temperature at which a given liquid boils. I was at my boiling point with the kids last night. All their fighting and shouting drove me crazy!2. The point at which a situation becomes critical, calamitous, or uncontrollable. Tensions in the region are at their boiling point—full-scale war seems inevitable now.See also: boiling, point

boil (something) away

To boil a liquid for so long that it evaporates. If you don't put the pasta in the pot soon, you will boil all of the water away.See also: away, boil

boil down

1. Literally, to reduce the amount of a liquid in a container through boiling. A noun or pronoun can be used between "boil" and "down." You'll get a better, more condensed flavor when you boil down the stock. The sauce will thicken when you boil it down.2. By extension, to reduce or simplify (something) to the most basic, essential, or fundamental element(s). Your essay is far too long. Please try to cut out any superfluous text and boil it down to about 10 pages. The issue really boils down to whether customers will be willing to pay more for the same product or not.See also: boil, down

boil (something) out of (something)

To use boiling water to clean a substance (such as a stain) from an item. Do you know if can you boil grass stains out of cotton?See also: boil, of, out

boil over

1. Literally, of a liquid, to boil so vigorously that it flows out of its container. If you put too much water in the pot, it might boil over.2. By extension, to become extremely intense or out of control, especially after a period of escalation. Usually said of emotions. Things had been tense between my aunts for months, and those feelings finally boiled over in a yelling match on our family vacation. This protest is in danger of reaching a point where it boils over into a violent confrontation.See also: boil, over

boil up

1. To prepare food in boiling water. A noun or pronoun can be used between "boil" and "up." I'm just boiling up some pasta for dinner—it will be ready soon.2. To increase in strength and intensity. Things had been tense between my aunts for a while, but those feelings really boiled up when they were forced to be together for days on our family vacation.See also: boil, up

boil with (an emotion)

To express or feel an emotion, typically anger, very intensely. Things are often tense between my mom and my aunt, so when they had to spend days together on our family vacation, they were soon boiling with anger. When I saw that someone had backed into my new car, I immediately boiled with rage.See also: boil

reach (a) boiling point

1. To reach a limit in patience, temper, or equanimity, after which one loses control of one's emotions. Likened to the temperature at which a given liquid boils. I reached a boiling point with the kids last night. All their fighting and shouting drove me crazy!2. To reach the point at which a situation becomes critical, calamitous, or uncontrollable. Tensions in the region have reached boiling point—full-scale war seems inevitable now.See also: boiling, point, reach

keep the pot boiling

1. To ensure that something remains active or engaging. The state department sent a representative to the talks to at least give the appearance of keeping the pot boiling, but it has become apparent that the administration has no real commitment to this cause. To keep the pot boiling in the sequel, the writer-director decided to add the main character's parents to the mix.2. To continue to rouse, incite, antagonize, or provoke someone or something. It's clear that the country's government intends to keep the pot boiling with separatists living in the outer reaches of their border. It is in their best interest to keep the pot boiling with the insurgency so that they can continue to benefit from financial and military aid.See also: boiling, keep, pot

boil the ocean

To engage in futile tasks. Oh, Ted's still boiling the ocean trying to find and reassemble that document from the shredded bin.See also: boil, ocean

have a low boiling point

To tend to become angry quickly or with little provocation. "Boiling point" here refers to one's limit in patience, temper, or equanimity, after which one loses control of one's emotions. (Likened to the temperature at which a given liquid boils.) A: "I can't believe Doug got so angry about such a minor mishap." B: "Yeah, he really has a low boiling point."See also: boiling, have, low, point

boil over

[for a liquid] to overflow while being boiled. (See also (with something)">boil over (with something).) The sauce boiled over and dripped onto the stove. Don't let the stew boil over!See also: boil, over

boil over (with something)

Fig. [for someone] to erupt in great anger. The boss boiled over with anger. Things got out of hand and the crowd's passions boiled over.See also: boil, over

boil something down

1. Lit. to condense or thicken something, such as a liquid. I have to boil this gravy down for a while before I can serve it. You boil down the sauce and I'll set the table. 2. Fig. to reduce a problem to its simple essentials. If we could boil this problem down to its essentials, we might be able to solve it. We don't have time to boil down this matter. This is too urgent.See also: boil, down

boil something up

Rur. to cook a batch of food by boiling. She boiled some beans up for dinner. She boiled up some potatoes.See also: boil, up

have a low boiling point

Fig. to anger easily. Be nice to John. He's upset and has a low boiling point. Mr. Jones sure has a low boiling point. I hardly said anything, and he got angry.See also: boiling, have, low, point

boil down

1. Simplify, summarize, or shorten, as in John finally managed to boil his thesis down to 200 pages. 2. boil down to. Be reducible to basic elements, be equivalent to. For example, What this issue boils down to is that the council doesn't want to spend more money. These metaphoric usages allude to reducing and concentrating a substance by boiling off liquid. [Late 1800s] See also: boil, down

boiling point

A climax or crisis; a high degree of fury, excitement, or outrage. For example, The union's disgust with management has reached the boiling point. This metaphoric term alludes to the temperature at which water boils. [Second half of 1700s] 2. have a low boiling point. Become angry quite readily, as in Don't tease her anymore-she has a low boiling point. This phrase means that it takes less heat than usual for a boiling point to be reached. [First half of 1800s] Also see boil over; make one's blood boil. See also: boiling, point

boil over

Erupt in anger, excitement, or other strong emotion. For example, The mere mention of a tax increase will make Kevin boil over. This phrase alludes to overflowing while boiling. [Second half of 1800s] See also: boil, over

reach boiling point

COMMON1. If an emotion, especially anger, reaches boiling point, it becomes so strong that it cannot be controlled. Her frustration and anger had reached boiling point. Note: You can also say that an emotion is close to boiling point. Tempers were already close to boiling point as the dispute continued for the ninth day.2. If a situation reaches boiling point, it becomes very dangerous or extreme and cannot be controlled. The situation reached boiling point after an argument between two teenagers, one white, one Asian, outside a fish and chip shop.See also: boiling, point, reach

keep the pot boiling

If you keep the pot boiling, you do something to make sure that a process does not stop or to make sure that a situation continues to be interesting. I threw in a question, just to keep the pot boiling while my brain caught up. Times being tough, the auctioneers have had to think up new ways of keeping the pot boiling. Note: This expression may refer to meat which is chopped into pieces and cooked in a pot. Alternatively, the `pot' may have been a melting pot, where metal objects were melted down. See also: boiling, keep, pot

keep the pot boiling

maintain the momentum or interest value of something.See also: boiling, keep, pot

boil down

v.1. To make an amount of liquid or food less in quantity or more concentrated by boiling it: You can boil down the leftover juices and make a nice sauce. The soup seemed thin, so I boiled it down.2. To condense something to its bare essentials; summarize: I boiled down my long report into a short two-page report. This plan is too long for me to read; can you boil it down for me?3. To have something as a basic or root cause: All of the complaints at work boil down to a lack of good leadership.See also: boil, down

boil over

v.1. To rise and flow over the sides of a container while boiling. Used of a liquid: I turned up the heat too high and the soup boiled over.2. To erupt in violent anger: When I realized I had been robbed, I boiled over and started yelling.See also: boil, over

boil up

v.1. To prepare some food by boiling it: I boiled up some lobster for supper. Let's boil the potatoes up and fry them with ham.2. To grow rapidly and steadily; escalate: Hostilities have been boiling up all over that part of the world.See also: boil, up

boil the ocean

tv. to waste one’s time attempting to do the impossible. (see also plowing water.) You’re wasting my time. You might as well be boiling the ocean. See also: boil, ocean

boiling (mad)

mod. very mad. Mad, I’m not mad. I’m just boiling. See also: boiling, mad

boiling

verbSee boiling mad

Boiling

A process in which a liquid phase is converted into a vapor phase. The energy for phase change is generally supplied by the surface on which boiling occurs. Boiling differs from evaporation at predetermined vapor/gas-liquid interfaces because it also involves creation of these interfaces at discrete sites on the heated surface. Boiling is an extremely efficient process for heat removal and is utilized in various energy-conversion and heat-exchange systems and in the cooling of high-energy density components. See Heat transfer

Boiling is classified into pool and forced-flow. Pool boiling refers to boiling under natural convection conditions, whereas in forced-flow boiling the liquid flow over the heater surface is imposed by external means. Flow boiling is subdivided into external and internal. In external-flow boiling, liquid flow occurs over heated surfaces, whereas internal-flow boiling refers to flow inside tubes. Heat fluxes of 2 × 10⁸ W/m², or three times the heat flux at the surface of the Sun, have been obtained in flow boiling. See Convection (heat)

Pool boiling

The illustration, a qualitative pool boiling curve, shows the dependence of the wall heat flux q on the wall superheat ΔT (the difference between the wall temperature and the liquid's saturation temperature). The plotted curve is for a horizontal surface underlying a pool of liquid at its saturation temperature (the boiling point at a given pressure).

Typical boiling curve, showing qualitatively the dependence of the wall heat flux q on the wall superheat ΔT

Several heat transfer regimes can be identified on the boiling curve: single-phase natural convection, partial nucleate boiling, fully developed nucleate boiling, transition boiling, and film boiling.

Forced-flow boiling

Forced flow, both external and internal, greatly changes the boiling curve in the illustration. The heat flux is increased by forced convection at temperatures below boiling inception, and after that the nucleate boiling region is extended upward until a flow-enhanced higher maximum flux (corresponding to point C) is achieved. Forced flow boiling in tubes is used in many applications, including steam generators, nuclear reactors, and cooling of electronic components.

Boiling

the transition of a liquid into vapor, accompanied by the formation of bubbles of vapor, or vapor cavities, in the fluid. The bubbles result from the evaporation of the liquid within them and float to the surface, where the saturated vapor they contain passes into the vapor phase above the fluid. Boiling begins when the liquid is heated to the point at which the pressure of the saturated vapor above its surface becomes equal to the external pressure. The temperature at which a liquid starts to boil under a constant pressure is called the boiling point (T_b). Strictly speaking, T_b corresponds to the temperature of the saturated vapor (saturation temperature) above the plane surface of the boiling liquid, because the liquid itself is always somewhat superheated relative to T_b. For a steady-state boiling condition there is no change in the temperature of the boiling fluid. If the pressure is increased, T_b, rises. The maximum boiling temperature is called the critical temperature of a substance. The boiling point under atmospheric pressure is usually cited as one of the basic physicochemical properties of a chemically pure substance.

To keep a liquid boiling, the heat that is expended in the formation of bubbles and in the work performed by the vapor against external pressure during the increase in volume of the vapor phase must be supplied. Thus, boiling is inseparably associated with heat transfer, which results in the transmission of heat from the heating surface to the liquid. The heat exchange during boiling is one of the forms of convective heat transfer.

A definite temperature distribution (Figure 1) is established in a boiling liquid: near the heating surfaces (the walls of the container, pipes, and so on) the liquid is appreciably superheated (T > T_b). The degree of superheating depends on a number of physicochemical properties of both the liquid and the boundaries of the solid surfaces. Carefully purified liquids that are free of dissolved gases (air) can be superheated by dozens of degrees without starting to boil when special measures are taken. However, when such a superheated liquid finally begins to boil, the process occurs very violently, resembling an explosion. The onset of boiling is accompanied by spattering of the liquid, hydraulic shocks, and sometimes even the destruction of the container. The heat of superheating is expended in the formation of vapor, so that the liquid is rapidly cooled to the temperature of the saturated vapor, with which it is in equilibrium. The substantial superheating of a pure liquid without boiling is explained by the difficulty of formation of initial small bubbles (nuclei); their formation is hindered by the considerable mutual attraction of the molecules of the liquid. The situation is different when the liquid contains dissolved gases and various extremely fine suspended particles. In this case even very little superheating (by tenths of a degree) produces steady, smooth boiling because the initial nuclei of the vapor phase are provided by gas bubbles and solid particles. The principal centers of vapor formation are at the points of the hot surface where there are very small pores holding adsorbed gas, as well as various irregularities, inclusions, and deposits that reduce the molecular adhesion between the liquid and the surface.

Figure 1. Temperature distribution in a layer of boiling liquid 6 cm thick at atmospheric pressure

After a bubble has been formed, it grows only if the vapor pressure in it is slightly greater than the sum of the external pressure, the pressure of the overlying layer of liquid, and the capillary pressure, which is due to the surface curvature of the bubble. To create the necessary vapor pressure within a bubble, the surrounding liquid, which is in thermal equilibrium with the vapor, must have a temperature higher than T_b. This type of boiling, called nucleate boiling, is observed in everyday practice (for example, when water is boiling in a teakettle). It takes place when the temperature T of the heating surface is slightly higher than the boiling temperature—that is, when the thermal head ΔT = T – T_b is very small. As the temperature of the heating surface rises, the number of vaporization centers increases sharply and an increasing number of freed bubbles comes to the surface of the liquid, thus causing intense agitation. This results in a substantial increase in the flow of heat from the heating surface to the boiling liquid (a higher heat transfer coefficient α = q/Δ T, where q is the heat flow density at the heating surface; see Figure 2). The amount of vapor being created increases correspondingly.

Figure 2. Change in the heat flow density q and the heat transfer coefficient α for water boiling at atmospheric pressure as a function of the thermal head ΔT T T,: (A) region of weak bubble formation, (B) nucleate boiling, (C) transitional boiling, (D) stable film boiling

When the maximum (critical) value of the heat flow (q_max) is reached, a second, transitional boiling mode begins. In this mode most of the heating surface is covered with dry spots because of the progressive coalescence of the vapor bubbles. The heat transfer and the rate of vapor formation are sharply reduced because the vapor has a lower heat conduction than the fluid, and so the values of q and α are markedly lower. The boiling approaches a critical point. When the entire heating surface is covered with a thin film of vapor, the third, or film, boiling mode develops. In this mode the heat is transferred by heat conduction and radiation from an incandescent surface to the liquid through a film of vapor. The nature of the change in q upon transition from one boiling mode to another is shown in Figure 2. When the liquid does not wet the wall (as, for example, mercury and alloyed steel), boiling occurs only in the film mode. All three boiling modes can be observed in the reverse order when a massive metal body is immersed in water for quenching: the water begins to boil and the body is cooled slowly at first (film boiling), then the cooling rate begins to increase rapidly (transitional boiling) and achieves the highest values in the final stage of cooling (nucleate boiling). The heat transfer in the nucleate boiling mode is one of the most efficient means of cooling; it is used in atomic reactors and for cooling jet engines. Boiling processes are also used extensively in chemical engineering, in the food industry, in the production and fractionation of liquefied gases, and for cooling units in electronic apparatus. The mode of nucleate boiling of water is used most widely in modern steam boilers at power plants to produce steam at high temperatures and pressures. Film boiling in steam boilers cannot be tolerated, since it may result in over-heating of the tube walls and in boiler explosions.

Boiling is possible not only when a liquid is heated under conditions of constant pressure. A decrease in external pressure at constant temperature can also cause a liquid to become super-heated and boil (because of a decrease in the saturation temperature). This explains, among other things, the phenomenon of cavitation—the formation of vapor cavities at low-pressure spots in a liquid (for example, in the turbulent area behind a steamship propeller). Boiling under reduced pressure is used in refrigeration engineering and in physics experiments.

REFERENCE

Kikoin, I. K., and A. K. Kikoin. Molekuliarnaia fizika. Moscow, 1963.
Radchenko, I. V. Molekuliarnaia fizika. Moscow, 1965.
Mikheev, M. A. Osnovy teploperedachi, 3rd ed. Moscow-Leningrad, 1956. Chapter 5.

D. A. LABUNTSOV

boiling

[′bȯil·iŋ] (astronomy) The telescopic appearance of the limbs of the sun and planets when the earth's atmosphere is turbulent, characterized by a constant rippling motion and lack of a clearly defined edge. (physical chemistry) The transition of a substance from the liquid to the gaseous phase, taking place at a single temperature in pure substances and over a range of temperatures in mixtures.

Boiling

Pool boiling

Forced-flow boiling

blowing

1. See popping. 2. The upward movement of soil material at the base of an excavation or cofferdam as a result of groundwater pressure.

boiling

boil·ing

boiling

boil•ing

boiling

boiling

boiling

boiling

boiling frog

boiling frog syndrome

boiling hot

boiling mad

boiling point

boil (something) away

boil down

boil (something) out of (something)

boil over

boil up

boil with (an emotion)

reach (a) boiling point

keep the pot boiling

boil the ocean

have a low boiling point

boil over

boil over (with something)

boil something down

boil something up

have a low boiling point

boil down

boiling point

boil over

reach boiling point

keep the pot boiling

keep the pot boiling

boil down

boil over

boil up

boil the ocean

boiling (mad)

boiling

Boiling

Boiling

Pool boiling

Forced-flow boiling

Boiling

REFERENCE

boiling

Boiling

Pool boiling

Forced-flow boiling

blowing

boiling

boiling

Patient discussion about boiling

boiling

Synonyms for boiling

adj very hot

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adj furious

Synonyms

Synonyms for boiling

adj marked by much heat

Synonyms

Synonyms for boiling

noun the application of heat to change something from a liquid to a gas

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noun cooking in a liquid that has been brought to a boil

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adv extremely

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