Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy and heat between physical systems. As such, heat transfer is involved in almost every sector of the economy. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, 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 exchange of kinetic energy of particles 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, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described by the second law of thermodynamics.
Dihydrogen monoxide (DHMO)
Hydrogen hydroxide (HH or HOH)
Michael Jackson and Bubbles is a porcelain sculpture (42 x 70.5 x 32.5 in) by the American artist Jeff Koons. It was created in 1988 within the framework of his seriesBanality.
The life-sized porcelain sculpture depicts the American singer-songwriter Michael Jackson leaning back on a flower bed. On his lap reclines his domesticated chimpanzee Bubbles who clasps a white cloth. Jackson and his pet form an optical unit. They wear similar clothing, are colored homogeneously and parts of their bodies are paralleled with each other, such as Jackson’s right hand and Bubble’s paw. The sculpture has been arranged in a triangular and multi-perspective composition.
In physics, superheating (sometimes referred to as boiling retardation, or boiling delay) is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid.
Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure (the atmospheric pressure, primarily). Below that temperature, a water vapor bubble will shrink and vanish.
A potometer (from Greek ποτό = drunken, and μέτρο = measure) —sometimes known as a transpirometer— is a device used for measuring the rate of water uptake of a leafy shoot. The causes of water uptake are photosynthesis and transpiration. Everything must be completely water tight so that no leakage of water occurs.
There are two main types of potometers used - the bubble potometer (as detailed below), and the mass potometer. The mass potometer consists of a plant with its root submerged in a beaker. This beaker is then placed on a digital balance; readings can be made to determine the amount of water lost by the plant. The mass potometer measures the water lost through transpiration of the plant and not the water taken up by the plant.
A phase transition is the transformation of thermodynamic system from one phase or state of matter to another.
A phase of a thermodynamic system and the states of matter have uniform physical properties.