Radiation efficiency
The radiation efficiency of a radiation source indicates what proportion of the energy used is converted into electromagnetic radiation ; the proportion is given in parts of a hundred, i.e. percent .
The radiation efficiency is used, for example, with antennas (see in detail under antenna # efficiency ), as well as with heat sources.
Efficiency with thermal radiation
In the case of heat sources, the thermal radiation efficiency indicates the proportion of thermal energy that is emitted to the environment in the form of thermal radiation . If it is not the radiation (emission) that is measured, but the immission (the impact), the radiation efficiency indicates what percentage of the amount of energy used arrives in the area of use. The difference to 100% consists in heat dissipation through heat conduction to the room air, in which the heat is then moved on by convection or on the wall via fastening systems. The radiation efficiency is also used as a measure of how heat is distributed in a room.
For gas-operated infrared heaters , in addition to the Gas Appliance Directive (90/396 / EEC), which stipulates the rational use of energy, the radiation efficiency or infrared component is also an assessment criterion for bright radiators and dark radiators. The decisive factor for economic efficiency is not the combustion efficiency, but the radiation efficiency described in DIN EN 416-2 / 419-2.
Since there are already subsidy programs in England, Belgium, Holland, the USA and Canada, in which devices with a radiation efficiency of over 50% are tax-favored, the trend is clear. Furthermore, from the manufacturer's point of view, it will be of interest across Europe in future to have devices assessed according to their radiation efficiency for reasons of competition. Radiant heat saves a lot of energy compared to conventional heating systems, e.g. T. up to 50%. This means that higher radiation efficiencies bring higher energy savings.
In the case of ceiling heating , heat conduction creates a cushion of heat which, due to the lower density and the buoyancy of the warm air, remains attached to the ceiling. The heat cushion gradually assumes the temperature of the radiation surface and because there is no longer any temperature difference, no heat can be given off into the boundary layer of the air cushion by conduction.
Individual evidence
- ↑ Hans Geiger , Karl Scheel (editor): Handbook of Physics, Volume XVII Electrical Engineering. P. 111 ( limited preview in Google Book search).
- ↑ Radiation efficiency : at energie-lexikon.info
- ↑ a b Thomas Kübler: Infrared heating technology for large rooms. ; Vulkan-Verlag, Essen, 2001, ISBN 3-8027-3505-6 , p. 163 ( limited preview in Google book search).
- ^ Hermann Rietschel: H. Rietschels textbook of heating and ventilation technology. Springer-Verlag, 2013, ISBN 978-3-662-25438-7 , p. 75 ( limited preview in the Google book search).