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Clothing Insulation
Clothing insulation is the thermal insulation provided by clothing.ANSI/ASHRAE Standard 55-2010, Thermal Environmental Conditions for Human Occupancy Even if the main role of clothing is to protect from the cold, protective clothing also exists to protect from heat, such as for metallurgical workers or firemen. As regards thermal comfort, only the first case is considered. Thermophysiological comfort Thermophysiological comfort is the capacity of the clothing material that makes the balance of moisture and heat between the body and the environment. It is a property of textile materials that creates ease by maintaining moisture and thermal levels in a human's resting and active states. The selection of textile material significantly affects the comfort of the wearer. Different textile fiber holds individual properties that suit in different environments. Natural fibers breathable and absorbs moisture, and synthetic fibers are hydrophobic; they repel moisture and do not allow air t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Insulation
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials. Heat flow is an inevitable consequence of contact between objects of different temperature. Thermal insulation provides a region of insulation in which thermal conduction is reduced, creating a thermal break or thermal barrier, or thermal radiation is reflected rather than absorbed by the lower-temperature body. The insulating capability of a material is measured as the inverse of thermal conductivity (k). Low thermal conductivity is equivalent to high insulating capability ( resistance value). In thermal engineering, other important properties of insulating materials are product density (ρ) and specific heat capacity (c). Definition T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin
The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907). The Kelvin scale is an absolute thermodynamic temperature scale, meaning it uses absolute zero as its null (zero) point. Historically, the Kelvin scale was developed by shifting the starting point of the much-older Celsius scale down from the melting point of water to absolute zero, and its increments still closely approximate the historic definition of a degree Celsius, but since 2019 the scale has been defined by fixing the Boltzmann constant to be exactly . Hence, one kelvin is equal to a change in the thermodynamic temperature that results in a change of thermal energy by . The temperature in degree Celsius is now defined as the temperature in kelvins minus 273.15, meaning t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Insulance
In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier under steady-state conditions. The ''R-value'' is the building industry term for thermal resistance "per unit area." It is sometimes denoted RSI-value if the SI units are used. An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window). In the case of materials, it is often expressed in terms of R-value per metre. R-values are additive for layers of materials, and the higher the R-value the better the performance. The U-factor or U-value is the overall heat transfer coefficient and can be found by taking the inverse of the R-value. It is a property that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duvet
A duvet (, ; ), usually called a comforter or (''down-filled'') quilt in US English, and a doona in Australian English, is a type of bedding consisting of a soft flat bag filled with either down, feathers, wool, cotton, silk, or a synthetic alternative, and is typically protected with a removable cover, analogous to a pillow and pillow case. The term ''duvet'' is mainly British, especially in reference to the bedding; when rarely used in US English, it often refers to the cover. Sleepers often use a duvet without a top bed sheet, as the duvet cover can readily be removed and laundered as often as the bottom sheet. Duvets originated in rural Europe and were filled with the down feathers of ducks or geese. The best quality feathers are taken from the eider duck, which is known for its effectiveness as a thermal insulator. Name The word duvet is of French origin, meaning "down". Its first known mention in English came in 1759, when Samuel Johnson used it in one of The Idler serie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Down Feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding (duvets and featherbeds), pillows and sleeping bags. The discovery of feathers trapped in ancient amber suggests that some species of dinosaur may have possessed down-like feathers. Description and etymology The word ''down'' comes from the Old Norse word ''dúnn'', which had the same meaning as its modern equivalent. The down feather is considered to be the most "straightforward" of all feather types. It has a short or vestigial rachis (shaft), few barbs, and barbules that lack hooks. There are three types of down: natal down, body down and powder down. Natal down is the layer of down feathers that cover most birds at some point in their early development. Precocial nestlings are alre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornell University
Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach and make contributions in all fields of knowledge—from the classics to the sciences, and from the theoretical to the applied. These ideals, unconventional for the time, are captured in Cornell's founding principle, a popular 1868 quotation from founder Ezra Cornell: "I would found an institution where any person can find instruction in any study." Cornell is ranked among the top global universities. The university is organized into seven undergraduate colleges and seven graduate divisions at its main Ithaca campus, with each college and division defining its specific admission standards and academic programs in near autonomy. The university also administers three satellite campuses, two in New York City and one in Education City, Qatar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tog (unit)
The tog is a measure of thermal insulance of a unit area, also known as thermal resistance. It is commonly used in the textile industry and often seen quoted on, for example, duvets and carpet underlay. The Shirley Institute in Manchester, England developed the tog as an easy-to-follow alternative to the SI unit of m2⋅K/W. The name comes from the informal word ''togs'' for 'clothing', which itself was probably derived from the word ''toga'', a Roman garment. The backronym ''thermal overall grade'' is also attested. The basic unit of insulation coefficient is the ''R''SI, (1 m2⋅K/W). 1 tog = 0.1 ''R''SI. There is also a US clothing unit, the clo, equivalent to 0.155 ''R''SI or 1.55 tog, described in ASTM D-1518. A tog is 0.1 m2⋅K/W. In other words, the thermal resistance in togs is equal to ten times the temperature difference (in °C) between the two surfaces of a material, when the flow of heat is equal to one watt per square metre. B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clothing Insulation
Clothing insulation is the thermal insulation provided by clothing.ANSI/ASHRAE Standard 55-2010, Thermal Environmental Conditions for Human Occupancy Even if the main role of clothing is to protect from the cold, protective clothing also exists to protect from heat, such as for metallurgical workers or firemen. As regards thermal comfort, only the first case is considered. Thermophysiological comfort Thermophysiological comfort is the capacity of the clothing material that makes the balance of moisture and heat between the body and the environment. It is a property of textile materials that creates ease by maintaining moisture and thermal levels in a human's resting and active states. The selection of textile material significantly affects the comfort of the wearer. Different textile fiber holds individual properties that suit in different environments. Natural fibers breathable and absorbs moisture, and synthetic fibers are hydrophobic; they repel moisture and do not allow air t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Manikin
The thermal manikin is a human model designed for scientific testing of thermal environments without the risk or inaccuracies inherent in human subject testing. Thermal manikins are primarily used in automotive, indoor environment, outdoor environment, military and clothing research. The first thermal manikins in the 1940s were developed by the US Army and consisted of one whole-body sampling zone. Modern-day manikins can have over 30 individually controlled zones. Each zone (right hand, pelvis, etc.) contains a heating element and temperature sensors within the “skin” of the manikin. This allows the control software to heat the manikin to a normal human body temperature, while logging the amount of power necessary to do so in each zone and the temperature of that zone. History Clothing insulation is the thermal insulation provided by clothing and it is measured in clo. The measuring unit was developed in 1941. Shortly afterward, thermal manikins were developed by the US Army f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Thermal Unit
The British thermal unit (BTU or Btu) is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. The modern SI unit for heat energy is the joule (J); one BTU equals about 1055 J (varying within the range 1054–1060 J depending on the specific definition; see below). While units of heat are often supplanted by energy units in scientific work, they are still used in some fields. For example, in the United States the price of natural gas is quoted in dollars per the amount of natural gas that would give 1 million BTUs (1 "MMBtu") of heat energy if burned. Definitions A BTU was originally defined as the amount of heat required to raise the temperature of 1 avoirdupois pound of liquid water by 1 degree Fahrenheit at a constant pressure of one atmospheric unit. There are several different definitions of the BTU that differ slightly. This ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hour
An hour (symbol: h; also abbreviated hr) is a unit of time conventionally reckoned as of a day and scientifically reckoned between 3,599 and 3,601 seconds, depending on the speed of Earth's rotation. There are 60 minutes in an hour, and 24 hours in a day. The hour was initially established in the ancient Near East as a variable measure of of the night or daytime. Such seasonal, temporal, or unequal hours varied by season and latitude. Equal or equinoctial hours were taken as of the day as measured from noon to noon; the minor seasonal variations of this unit were eventually smoothed by making it of the mean solar day. Since this unit was not constant due to long term variations in the Earth's rotation, the hour was finally separated from the Earth's rotation and defined in terms of the atomic or physical second. In the modern metric system, hours are an accepted unit of time defined as 3,600 atomic seconds. However, on rare occasions an hour may incorporate a positive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fahrenheit
The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a salt). The other limit established was his best estimate of the average human body temperature, originally set at 90 °F, then 96 °F (about 2.6 °F less than the modern value due to a later redefinition of the scale). For much of the 20th century, the Fahrenheit scale was defined by two fixed points with a 180 °F separation: the temperature at which pure water freezes was defined as 32 °F and the boiling point of water was defined to be 212 °F, both at sea level and under standard atmospheric pressure. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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