The radiant heating and cooling system refers to temperature controlled surfaces that exchange heat to the surrounding environment through convection and radiation. By definition, in radiant heating and cooling systems, heat radiation covers more than 50% heat exchange in the chamber. Hydro-radiation heating and water-based cooling systems. This refers to a panel or component of an embedded building (floor, ceiling or wall). Other types include air and power systems (which use electrical resistance for mainly heating purposes). Important parts of the building's surface are usually required for luminous exchanges.
Video Radiant heating and cooling system
Apps
Serial heating and cooling systems can be used in commercial, residential, educational and recreational buildings, museums, hospitals, and other types of buildings. Applications depend on the type of radiant system (see below the type of radiation system), on climatic conditions and on the ventilation system used.
Maps Radiant heating and cooling system
System description
Radiation heat exchange
Heat radiation is energy in the form of electromagnetic waves emitted by solid, liquid, or gas as a result of its temperature. In buildings, the radiant heat flow between two internal surfaces (or surface and one) is affected by the emissivity of the hot jets surface and by the view factor between this surface and the receptive surface (object or person) indoors. The heat transfer by radiation is proportional to the power of four of the absolute surface temperatures.
The emissivity of the material (usually written? Or e) is the relative ability of its surface to radiate energy by radiation. The black body has emissivity 1 and the perfect reflector has an emissivity of 0.
In radiation heat transfer, the display factor quantifies the relative importance of radiation leaving objects (people or surfaces) and other strikes, considering other surrounding objects. In the appendix, the radiation leaving the surface is conserved, therefore, the sum of all view factors associated with the given object is equal to 1. In the case of the room, the surface display factor glows and the person depends on their relative position. As people often change positions and as space may be occupied by many people at the same time, diagrams for omnidirectional people can be used.
Operating temperature and thermal comfort
The operating temperature is a thermal comfort indicator that takes into account the effects of both convection and radiation. The operating temperature is defined as a uniform temperature of a radiant black beam in which an occupant will exchange the same amount of heat as radiation plus convection as in an uniformly actual environment.
With radiant systems, thermal comfort is achieved at warmer interior temperatures than air systems for cooling scenarios, and at lower temperatures of all air systems for heating scenarios. Thus, a luminous system can help to achieve energy savings in building operations while maintaining the expected level of comfort.
Asymmetry of radiation temperature
The radiant temperature asymmetry is defined as the difference between the temperature of the plane's emission from two opposite sides of a small plane element. Regarding occupants in buildings, the field of thermal radiation around the body may not be uniform because of hot and cold surfaces and direct sunlight, causing local discomfort. The ISO 7730 norm and the ASHRAE 55 standard give a prediction of the percentage of dissatisfied residents (PPD) as a function of radiant temperature asymmetry and set acceptable limits. In general, people are more sensitive to asymmetric radiation caused by warmer ceilings than those caused by hot and cold vertical surfaces. The detailed percentage calculation method is not satisfied because of the radiant temperature asymmetry described in ISO 7730.
Design considerations
While the specific design requirements will depend on the type of luminous system, some common problems for the most shining system.
- For cooling applications, emission systems can cause condensation problems. The local climate needs to be evaluated and taken into account in the design. Air dehumidification may be necessary for moist climates.
- Many types of radiant systems incorporate large building elements. The involved thermal mass will have consequences on the thermal response of the system. The operating schedule of space and control strategies of the beam system play a key role in the functioning of the system.
- Many types of radiant systems incorporate hard surfaces that affect indoor acoustics. Additional acoustic solutions may need to be considered.
Hydraulic radiation system
Depending on the position of the pipeline in the building construction, the hydradiation radiation system can be divided into 4 main categories:
- Embedded Surface System : pipes embedded in the surface layer (not inside the structure)
- Thermal Active Building System (TABS) : thermal cycling pipes and embedded in building structures (sheets, walls)
- Capillary Surface System : pipes embedded in the inner layers of the inner ceiling/wall
- Radiant Panels : metal pipes are integrated into panels (not inside structures); the hot carrier is close to the surface
Type (ISO 11855)
The ISO 11855-2 norm focuses on embedded water heating and cooling systems and TABS. Depending on the construction details, this norm distinguishes the 7 types of systems (Type A through G)
- Type A with pipes embedded in a screed or concrete ("wet") system
- Type B with pipe embedded outside screed (in thermal insulation layer, "dry" system)
- Type C with a pipe embedded in the leveling layer, above which the second screed layer is placed
- Type D includes a plane part system (plastic/extrusion group of the capillary grid)
- Type E with a pipe embedded in a large concrete layer
- Type F with capillary pipe embedded in layers in the inner ceiling or as a separate layer in gypsum
- Type G with pipe embedded in wood floor construction
Energy source
The radiation system is associated with a low-exergy system. Low eksergi refers to the possibility to utilize 'low quality energy' (ie scattered energy that has little ability to perform useful work). Heating and cooling in principle can be obtained at a temperature level close to the surrounding environment. Low temperature differences require that heat transmissions occur over relatively large surfaces such as for example applied to ceilings or under floor heating systems. Radiation systems using low temperature heating and high temperature cooling are typical examples of low-allergy systems. Energy sources such as geothermal (direct cooling/heating geothermal heat pumps) and solar thermal water are compatible with luminous systems. These sources can lead to important savings in terms of primary energy use for buildings.
Important building using luminous system
Building map using hydronic radiation heating and cooling system
Non-hydronic radiation system
References
External links
- Cooling radiant research at the Center for the Built Environment
Source of the article : Wikipedia
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