Radiant heating systems, particularly in industrial and commercial facilities around the world since the 1950s finds itself in the application area, it is also used in our country since the early 1990s.According to the principles of radiant heating system it is different from conventional heating systems.heat transfer in conventional heater “convection (convection)” media made by air increased thermal comfort by introducing a certain temperature.However, if the radiant heater, another type of heat transfer to “radiation” they heat the body by emitting.heat transfer by radiation; At finite temperature (0ºK above) every body, because of the movement of electrons changes in the structure of atoms or molecules emit electromagnetic waves. Increased body temperature, atoms and electromagnetic wave of violence that increase the movement of molecules that heat radiation is also increasing off the first radiation effects in places in the application is felt and heat energy received by the convection of air heated body in the later venue. This basic principle raises many advantages, especially in high places and outdoor heating. where hot air is blown heated, hot air, cold air because there is a less density accumulates on the roof rises environment. In this case, the height increases, increasing the air temperature at the base is increasingly difficult.
The working principle of radiant heaters is very simple. With the help of burning gas in the burner chamber vacuum fan moves the heat in special quartz tube, leaving coated pipe. Located on the heat emitted by the pipe is transmitted to the ground reflected by the reflector help.
It is the most beautiful example of the Earth and solar radiation heat transfer path
Radiant Heaters Types
Radiant heaters practice can be examined under two main groups:
Low Intensity Radiant Heaters:
Radiant heater surface temperatures below those density between 200 and 815 ° C radiant heaters called [RG]. wavelengths of the radiation emitted from the surface of this heater may vary between 2 and 10 microns. various types of pipe heaters (gas-fired) and household-type electric heater is located in this category.
Pipe type radiant heaters are examined under two main headings:
1. One of the pipe burners
2. Multi-burner is piped
One burner is Tube Radiant Heaters:
TSE Turkish Standards Institute standard EN 416-1 No. 1 mentions only burners Radiant heating systems. One burners heaters, such as plain and types grouped under two main headings. Straight seen in Figure 3, the radiant heater in a vacuum. Burner (1), Pipe (2), reflective reflector (3), and Vacuum Fan (4) The working principle of this device consists of four main parts, including the following:
One type of flat tube radiant burners
1. The device initially works and creates a vacuum inside the vacuum fan when executed by sucking air in the radiant tube inside throw out.
2. The vacuum level of the vacuum switch modules connected to the ignition of the burner when it reaches a certain value feel it and opens the ignition circuit.
3. The ignition circuit is switched on, the burner’s electronic solenoid valve allows for the gas supply and the ignition electrode begins the era of the device at the same time.
4. occurred in the burner flame when the gas-air mixture ratio to an appropriate level. It is absorbed by the vacuum fan at the end of the flame system.
5. burnt gas which has to cover all the radiant tube to get out of the system, are absorbed by heating pipes.
6 heat pipes begin to emit radiation. If the rays are reflected from the surface down through the pipe of the reflector.
7. Thus, the gas is burned to heat the radiant tube springs out and converted to a radiation objects at the bottom of the device, people, machines, floor etc. whereby hot.
Flat type heaters, when heated space all and devices may have the temperature distribution is appropriately positioned. In fact, in this case the homogeneous heat distribution is not as important as spot heating.
Total installed capacity in 30 minutes to reach the venue is cold comfort temperature should be selected. Changes in temperature distribution in a system of this design is not disturbing. In addition, the direction of the burner device to distribute heat evenly and is very heat loss or, if it is equivalent to the door or window side, the more uniform temperature distribution has been carried out.
The differences in the distribution of flat type radiant heaters heat gave rise to the development of the tube-type radiant heater that resolves this disadvantage. The main difference of the U-type heater, the heater is formed into a flat type with a double row of tubes with a single row of radiant tubes.
Examples of the types of radiant tube
It is a vacuum tube-type radiant heater, fan, but still depends on the final pipe, eliminating device is a two-storey flat heater comes alongside the hot pipe surface with the cold pipe surface. This situation continued throughout the entire heating surface. For example the hot pipe surface 650ºC in a heater, the cold surface is about 120 ° C, and it is from side to side surface side. The next pipe pipe surface temperature of 350ºC, which is still in the same heater is around 350ºC. This feature compared to straight tube-type heaters are radiant heaters allows them to have a more uniform heat distribution.Therefore, the heaters are able to better respond to the needs of direct and local heat.
Multi-burner is Tube Radiant Heaters
Turkish Standards Institute TSE EN 777-1, TS-EN 777-2, TS-EN 777-3 and TS EN 777-4 standard include multi burner is No. Type Radiant Tube Heaters. This standartlartd 4 types of radiant heaters very burners are mentioned:
D Type Very burners heating: you’ve finally found a fan in the fan There were no common line they are affiliated with a secondary burner and all connected devices with even just one burner.
E-type multi burners heating: Each burner with its own fan but are not connected to other fans on the common line and each sub-system are connected even just a burner.
F-type multi burners heating: each with its own fan and a burner connected to a common fan is located at the common line and each sub-system are connected even just a burner.
H-type multi burners heater: more than one burner on the same line as the common fan with a line attached to two or more burners and systems used for each secondary line.
mentioned above in many burners, depending on the type of system, a number of advantages over single burners of said device. However, H-type devices in productivity and low fuel consumption, they come to the fore. exhaust gas is used for multiple burners throughout the pipeline H type device temperature can be reduced so as to maximize the efficiency of the system. It can also be used in relatively small capacity burners at frequent intervals, the temperature distribution becomes more uniform.
High-Intensity Radiant Heaters
Radiant heaters with a surface temperature of 815 ° C and over High Density called radiant heaters.wavelengths of the beams emitted from the surface of high density heater is between 1 and 6 microns. Ceramic plate heater (natural gas), ceramic plates garden, patio and terrace heaters and a high surface temperatures, especially industrial type electric radiant heaters are included in this category.
Ceramic plate radiant heaters, open flame can be also called in the literature. Open flame is due to the form of expression of these devices spread my heat. Devices operate in the manner described below:
1 is sent to the inside by means of a venturi jet orifice and the gas causes the pressure drop across the venturi. This decline is due to air is sucked from the atmosphere into the vacuum effect occurs within and devices.
2. In accordance burn rate of the gas jet Venturi structure is designed to absorb air. Whereby the fuel mixture at room ideal combustion to obtain access to air gas conditions.
3. It reaches blending ceramic plate and tries to escape through the holes in the plates. It burned in exactly where you go out to create a short flame in the ceramic surface. So each hole actually works like a burner.
Ceramic Plate Radiant Heaters
4. Increase the temperature of the ceramic on ceramic surfaces and hence short flame causes the redness. My warm thanks to glowing ceramics begins to spread and reflectors are also directed to the lower level of the device.
5. Device in some heaters so as to increase the efficiency of isolation and thermal inertia of the reserve which steel wire cages may be used.
Radiant Ceramic Plate
Comparison of Low and High Density Heater
I hotter heat transfer with the heat of the surface where the temperature is proportional to the fourth power and surface area. That is, a body surface area is kept constant when removed the surface temperature of the second layer with the heat energy emitted from that surface, the full 16-fold increase. by keeping the temperature constant, and when the surface area taken two times hotter violence also leads to a 2-fold. When the same capacity with both high density and low density heaters analyzed, low intensity radiant heaters have a lower surface temperature than the high density devices. In this case, the heat emanating from the surface of the unit, it means a lower energy. However, the surface areas of low density unit is much higher than the high density devices.If the low and high density are two different devices of the same capacity is exceeded at the same height, low density heater emits energy more space, while a smaller area of high density heater may raise to a higher temperature. These two features are to the fore in different application areas. If all the desired space to be heated, that will be a general warming in this case, it may be more efficient to choose radiant tube heater that can cover more area. The high-density devices “spot” called heating, regional, able to respond better to direct heat needs in places where poor local needs and isolation. In contrast, from application to application and device use may vary depending on the user’s preference. devices for spot heating of low density and high density device likewise also possible to use general heating purposes.
Application of Radiant Heaters
Gas-fired radiant heaters in the first place for various needs in today if they have developed can also be used for industrial applications. In practice, tubular heater of 4 m, while the open flame heaters are mounted at a height of less than 5 m are not preferred because it causes a feeling of overheating.
Radiant heaters, especially the big ones are difficult or impossible with traditional methods of heating and high places, the places where isolation is bad, can provide heating quite successfully in a half-open or outdoor heating applications. Factories, workshops, service stations, churches, stadiums, gymnasiums, warehouses, hangars, fair exhibition halls, greenhouses, livestock farms are shown as examples.
• boiler does not require and equipment.
• Provides a minimum temperature difference between the floor and ceiling.
• Easy installation and low cost of investment pays for itself in a short time.
• it can be heated to different temperatures in different areas.
• Natural gas LPG, LNG and diesel fuel is possible to use options.
space heating with hot air and radiant heaters
• How the above table in the space left by the heated air rises in the area heated by hot air you can see the emergence of their losses. heating warm air moves away from the desired collected above ground.
• Radiant floor heating system in the right table up in the heat of the radiant heating system it is possible to clearly see how the main focus. heating temperature directly sends the desired floor.
• can not be air circulation do not carry dust and particles.
• that these systems provide many advantages compared to conventional blown system and especially before investing significant savings in operating costs later. (50% savings)
• provide a healthy environment with comfortable heating.
• Practical application shows that, in order to 1.8m air temperature at a height 18ºc’y to the ground in a structure 10 m in the air blast system sulky six temperature while finding about 30ºc’y, the temperatures in buildings that use radiant heater is around 21ºC.