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Boiling
Boiling or ebullition is the rapid phase transition from liquid to gas or vapor, 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 Standard atmosphere (unit), surrounding atmosphere. Boiling and evaporation are the two main forms of liquid vapourization. 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 vapour forms on the surface. Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes. Boiling water is used as a method of making it potable by killing Microorganism, microbes an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum, i.e., under a lower pressure, has a lower boiling point than when that liquid is at atmospheric pressure. Because of this, water boils at 100°C (or with scientific precision: ) under standard pressure at sea level, but at at altitude. For a given pressure, different liquids will boiling, boil at different temperatures. The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, one Atmosphere (unit), atmosphere. At that temperature, the vapor pressure of the liquid becomes sufficient to overcome atmospheric pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Water - Close Up (short Shutter Speed)
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. Boiling and evaporation are the two main forms of liquid vapourization. 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 vapour forms on the surface. Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes. Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. The sensitivity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Boiling
In fluid thermodynamics, nucleate boiling is a type of boiling that takes place when the surface temperature is hotter than the saturated fluid temperature by a certain amount but where the heat flux is below the critical heat flux. For water, as shown in the graph below, nucleate boiling occurs when the surface temperature is higher than the saturation temperature () by between . The critical heat flux is the peak on the curve between nucleate boiling and transition boiling. The heat transfer from surface to liquid is greater than that in film boiling. Nucleate boiling is common in electric kettles and is responsible for the noise that occurs before boiling occurs. It also occurs in water boilers where water is rapidly heated. Mechanism Two different regimes may be distinguished in the nucleate boiling range. When the temperature difference is between approximately above TS, isolated bubbles form at nucleation sites and separate from the surface. This separation induces c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapourization
Vaporization (or vapo(u)risation) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon (a phenomenon in which the whole object or substance is involved in the process). Evaporation Evaporation is a phase transition from the liquid phase to vapor (a state of substance below critical temperature) that occurs at temperatures below the boiling temperature at a given pressure. Evaporation occurs ''on the surface''. Evaporation only occurs when the partial pressure of vapor of a substance is less than the equilibrium vapor pressure. For example, due to constantly decreasing pressures, vapor pumped out of a solution will eventually leave behind a cryogenic liquid. Boiling Boiling is also a phase transition from the liquid phase to gas phase, but boiling is the formation of vapor as bubbles of vapor ''below the surface'' of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, Convection (heat transfer), thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species (mass transfer in the form of advection), either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system. Heat conduction, also called diffusion, is the direct microscopic exchanges of kinetic energy of particles (such as molecules) or quasiparticles (such as lattice waves) through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cooking
Cooking, also known as cookery or professionally as the culinary arts, is the art, science and craft of using heat to make food more palatable, digestible, nutritious, or Food safety, safe. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric stoves, to baking in various types of ovens, reflecting local conditions. Types of cooking also depend on the skill levels and training of the Cook (profession), cooks. Cooking is done both by people in their own dwellings and by professional cooks and chefs in restaurants and other food establishments. Preparing food with heat or fire is an activity unique to humans. Archeological evidence of cooking fires from at least 300,000 years ago exists, but some estimate that humans started cooking up to 2 million years ago. The expansion of agriculture, commerce, trade, and transportation between civilizations in different regions offered cooks many new ingredients. New inventions and technolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapour Pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid (or solid) in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as '' volatile''. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions. The vapor p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid
Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Therefore, liquid and solid are classified as condensed matter. Meanwhile, since both liquids and gases can flow, they are categorized as fluids. A liquid is composed of atoms or molecules held together by intermolecular bonds of intermediate strength. These forces allow the particles to move around one another while remaining closely packed. In contrast, solids have particles that are tightly bound by strong intermolecular forces, limiting their movement to small vibrations in fixed positions. Gases, on the other hand, consist of widely spaced, freely moving particles with only weak intermolecular forces. As temperature increases, the molecules in a liquid vibrate more intensely, causi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poaching (cooking)
Poaching is a cooking technique that involves heating food submerged in a liquid, such as water, milk, stock (food), stock or wine. Poaching is differentiated from the other "moist heat" cooking methods, such as simmering and boiling, in that it uses a relatively lower temperature (about ). This temperature range makes it particularly suitable for delicate food, such as egg (food), eggs, poultry, fish and fruit, which might easily fall apart or dry out using other cooking methods. Poaching is often considered a healthy cooking method because it does not use fat for cooking or flavoring the food. Variations Shallow poaching This moist-heat cooking method uses a sautoir or other shallow cooking vessel; heat is transferred by conduction from the pan, to the liquid, to the food. Shallow poaching is best suited for boneless, naturally tender, single-serving-size, sliced, or diced pieces of meat, poultry, or fish. This preparation involves smearing the inside of the pan with whole bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
