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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 (mass transfer in the form of advection ), either cold or hot, to achieve heat transfer.
Ancient heating systems, including hearths, furnaces, and stoves, operated primarily through convection.Fixed central hearths, which were first excavated and retrieved in Greece, date back to 2500 BC, whereas crude fireplaces were used as early as the 800s AD and in the 13th century, when castles in Europe were built with fireplaces with a crude form of chimney.
It quantifies how effectively a material can resist the transfer of heat through conduction, convection, and radiation. It has the units square metre kelvins per watt (m 2 ⋅K/W) in SI units or square foot degree Fahrenheit–hours per British thermal unit (ft 2 ⋅°F⋅h/Btu) in imperial units. The higher the thermal insulance, the better a ...
Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout.
A radiator is a device that transfers heat to a medium primarily through thermal radiation.In practice, the term radiator is often applied to any number of devices in which a fluid circulates through exposed pipes (often with fins or other means of increasing surface area), notwithstanding that such devices tend to transfer heat mainly by convection and might logically be called convectors.
A Franklin stove. The Franklin stove is a metal-lined fireplace named after Benjamin Franklin, who invented it in 1742. [1] It had a hollow baffle near the rear (to transfer more heat from the fire to a room's air) and relied on an "inverted siphon" to draw the fire's hot fumes around the baffle. [2]
Oil heaters transfer heat by convection and radiation. [4] They can silently heat larger rooms, but take longer to heat up. Like infrared models, they lack a fan, but circulate heat according to a room's air patterns, which is why it may take longer for a user to discern a difference in temperature.
Fireplaces and woodstoves A fireplace provides radiant heating, but also draws in cold air. A: Air for the combustion, in drafty rooms pulled from the outdoors. B: Hot exhaust gas heats building by convection as it leaves by chimney. C: Radiant heat, mostly from the high temperature flame, heats as it is absorbed