Principle of IR heating
Since radiation heating basically delivers heat directly to the space so heated, it is – when compared with the convection or hot-air heating – very economical. In many situations (especially in large halls) it is the only method available to heat the hall central area as required, without overheating the roof space.
Is the cases the advantages of above mentioned IR radiator heating may come in handy.
Such a system of heating is usually installed to suit the needs of people working in these premises, and therefore not only the general need of heat comfort, but also the activity performed by the people there should be taken into account. A sedentary job requires conditions different from those suitable for easy or hard physical work; another consideration is the time that the people spend in the premises, etc. All these aspects are of major importance for proper design and operation of heating systems based on infrared radiators.
Scope of application
Gas-fuelled infrared radiators are mainly designed for:
- heating of high premises such as industrial halls, warehouses, sports hall, churches, etc.
- heating of irregularly utilized buildings
- moderate heating of exteriors such as stadium tribunes, garden restaurants, platforms, etc.
- process heating, e.g. tubs with containing various baths etc.
- firing
- drying
- de-icing
- dehumidifying of buildings after flooding
Light-body IR radiators
The light-body radiator delivers heat generated in ceramic plates heated up to 850°C to 950°C (the radiator emits light). The energy radiation is very intense and the device becomes a point heat source. The energy can be delivered to the heated surface over large distances thus offering the possibility of heating self-contained work sites or confined zones.
The air-gas mixture passes through a diffuser, a radiator chamber and ceramic plates; the flameless catalytic combustion occurs at the plate surface. The resulting low-temperature combustion generates a substantially lower volume of flue gas (particularly NOx) than that encountered in conventional burner combustion (with the flame temperature of approx. 1200 °C).
Dark-body IR radiators
"Dark-body tube-shaped radiators" feature a lower surface temperature (350°C to 550°C) and a larger radiating surface. These are open or covered gas appliances used for direct heating and fitted with a flue gas forced draught system; the combustion space may be designed for both underpressure and overpressure operation and the different designs bring the related advantages and disadvantages. The beam of radiation is directed by a reflector.
Compact low-temperature IR radiators
The low-temperature gas-fuelled IR radiators work on the principle of circulation of hot burned gas inside tubes. The circulating hot gas heats the tube surface, whose lower half (covered with a special high-emissivity coat) irradiates energy into the space to be heated. Heat radiation in undesired directions is prevented by means of heat-insulated covers.
The gas is burned in a burner entering the first module of the IR radiator. The first module is used to mix the circulating burned gas with the fresh burned gas. The process of mixing is controlled so that the temperature along the entire IR radiator length is uniform.
The burned gas sucked inside from the radiant tube is blown to the chamber; a portion of approx. 10% is dumped into the stack, while the remaining 90% is recirculated and mixed with the freshly burned gas. With the burner turned off the stack inlet is closed and the heat accumulated in the circulating gas is utilized without any stack loss. The optimal average surface temperature to be set is 200 °C to 250 °C.
This sophisticated low-temperature process of heating provides for uniform distribution of temperature within the heated space; the use of intensive recirculation enables to achieve significant energy economies - fuel efficiency may be up to 95%, while the temperature loading of the entire system is markedly lower than the case is with the classical dark-body radiators.
