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Insulated Pipes
Insulated pipes (called also preinsulated pipes or bonded pipe ) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The main purpose of such pipes is to maintain the temperature of the fluid inside the service pipes. Insulated pipes are commonly used for transport of hot water from district heating plants to district heating networks and for distribution of hot water inside district heating networks. Thermal insulation material usually used is polyurethane foam or similar, with a thermal conductivity λ50 of about 0.024–0.033 W/(m·K). Outer casing is usually made of high-density polyethylene (HDPE). Preinsulated pipes for district heating are described in European standards EN 253 and EN 15698-1. EN 253 describes "District heating pipes - Bonded single pipe systems for directly buried hot water networks - Factory made pipe assembly of steel service pipe, po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is also often used to refer to the thermal energy contained in a system as a component of its internal energy and that is reflected in the temperature of the system. For both uses of the term, heat is a form of energy. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is "conducting heat" from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat. The hot metal bar is also transferring heat to its surroundings, a correct statement for both the strict and loose meanings of ''heat''. Another example of informal usage is the term '' heat content'', used despite the fact that p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
