Radiant Heaters and Accounting Method
Radiant heaters, hot water radiant panels and natural gas can be divided into radiant tubes. Radiant panels arranged with large volumes of hot water can be heated from the ceiling. Here are just large volumes, factories and natural gas used for heating the workshop will focus on r-heaters.
These heaters are preferred in the following heating applications:
1-Ceiling height of 6 m and above the closed areas
2-Partially enclosed areas
3-Large in volume, the heating of a particular area (for example a particular machine and the environment in a large manufacturing hall)
4- Briefly heated to the desired areas.
These heaters in gas combustion heat from radiant heat panels as a result, the surface is directed by radiation ( radiation ) are transferred. radiation switching devices to be used in place of the r-heater (high benches, buses, trucks, etc.) should be available.
Radiation passed by heating the ambient air, provided an efficient heating that warms the body to be heated directly. Heat then passes to the surface of the heated air convection environment.
Consequently, a temperature profile equal along the entire height can be obtained and the local heating. However, the above conventional convective hot air heating and local heating can not be collected. Therefore, high ceilings, large volumes of heating: heating with radiant panels, 25% of the convective heating – 50% energy saving is concerned. The radiant heaters used in industry can be divided into open flame and radiant plate radiant tube heaters.
Outdoor Burning Room Radiant Heaters
This type of heater is the most widely accepted of gas-fired radiant heating system and is the oldest.Fifty years more time since they are used successfully to save energy.
Open combustion chamber fully pre-mixed gas-fired radiant heaters directly by an injector burner (direct) is heated. Gas / air-mixture is burned on the surface of a ceramic plate. Extreme burning on the inside of the ceramic plate and the hole is provided with a short flame length. Surface temperature is about 850 to 900 ° C. Ceramic emits infrared radiation in the wavelength region between 0.8 to 3mm. Ceramic surface for which emit radiation in the visible wavelength blushing so bright is also called radiant heaters to the heater. a radiation grating placed in front of the ceramic provides increased yields. reflectors have very different geometries (reflectors) provides an adaptation common to these applications. Radiation area where people or materials to be heated to the required large area or concentrate (condense) the transfer by steep and curved parabolic reflectors are used. Structural requirements necessary to be inclined to install a radiant heater, special asymmetrical reflectors are avoid radiation losses towards the roof. Such radiant heaters are virtually trouble-free way to do duty for a period of over ten years and they have no moving parts.Open combustion chamber (bright) with radiant heaters detail improvements have been applied to the devices, mainly to raise the amount of radiation as the yield increase hedeşe are provided. open in a new type of combustion chamber radiant heaters, insulated and covered with a reflective.Although the parties differ flue gas flowing through the interior of the heat flow is transferred to the reflective mirror, so that the heat energy balance. So that the inside of the reflector is heating to a temperature of approximately 300 ° C and the long wavelength radiation to the area where people (secondary radiation) emits. The reflector inside the chimney (waste) and H2O gas bag in addition to the lower side due to the amount of CO2 gas emits radiation. Reflecting body of the combustion chamber (cell) as provided by the geometric shape placement in special gas / air mixture pre-heating which makes greater use of energy possible.
In open combustion chamber radiant heater flue gases can be discharged through an exhaust system and either a mechanical space ventilation. Mechanical if used in ventilation systems installed kW of radiant heaters per power 30m3 / h is necessary to provide a fresh air flow. This field comes from the amount of air space volume is carried by the roof ventilators. Open combustion chamber roof fans are commissioned with radiant heaters (to run) or is stopped. the amount of air taken off per hour corresponds to approximately 0.1-0.4 air exchange building. Commercial buildings are normally 0.7 to 2 times the natural air changes per hour (depending on the tightness of the building) is, so open combustion chamber fresh air intake caused by radiant heaters are full of natural air exchange in the building; additional energy costs arise.
Tube Radiant Heaters
The following figure is a tubular radiant heater shown schematically.
Tube heaters are produced from 65 to 104 mm diameter steel pipe. the other end is drawn by fan assistance gas is combusted and the combustion products are expelled from one end. 7M tube lengths may be up to approximately 18 kW and length can be obtained. In the open flame heater radiant heater every kW of power per 14-24 m3 / h ventilation should be provided and room volume should be less than 10 m3 per kW worth. Generally, the ceramic heater surface can reach temperatures of 800-900 ° C. Average heating surface heat emission intensity of 50-130 kW / m2 in.protection combustion in radiant heaters are provided with a flame ionization method. Although the ignition pilot flame in some applications, AnIdIr carried out with the best of auto ignition system. air flow and the air flow switch radiant heater pipes must be checked. Large heater for heating control, room thermostat with the help of accomplished fully automatically.
Radiant Heating Calculation Method
heat loss calculation according to methods known in the volume to be heated by radiant heaters are made. For example: DIN 4701 are determined based on the volume of the heat requirement. for underfloor radiant heaters to be placed higher than 5m in additional volume of heat loss per meter 3,3% add-ons to be made. Found total heat load of the burner thermal power divided by the number of necessary defense (or the number of radiant heaters) are available. a part in determining the number Bakr advised to be treated safely. Determination of heater power only based on heat loss and placed, it may produce undesirable results. Also the heat density on the surface to be heated has to be controlled. In the partially enclosed space heating performed in, ensuring the surface to be heated entirely calculation method is based on the required heat density.
Recknagel recommended by the forces which:
a-Proper conditions, a company, a power of 3.5 kW radiant heaters in enclosed spaces in not lower than 4 m ceiling height 10 15 m2 of surface heat.
b-Unfavorable conditions (high room temperature, more ventilation, large heat loss) 8-10 m2, this value goes down.
Moreover head by Recknagel level of heat intensity for the people shall not exceed the following values:
While the room was a- sıcaklığı12 ° C q = 30-40 W / m2
b “” 15 ° C, while q = 17-30 ”
c- “” While 18 ° C q = 14-17 ”
d- “” While 20 ° C q = 12-14 ”
The difference H height connected in parallel, as in Figure Coefficient of Variation between two flat Surface
This heat flux density, the strength of the source is dependent on the distance to said surface from the source.
Q = a.ψ.a. (ts-tm) W / m2
Radiation heat transfer coefficient is a = approximately 88 W / m2K can be.
ψ = it is the coefficient figure. Figures available from 6:20.
A = surface of the radiant heater, m2
ts and tm = radiant heating surface with the order, and are the ambient temperature. (° C)
Installation design, while the location of the gas supply and electricity supply to the placement of the meter must be taken into account. Measures should be taken to collect and drain condensate gas products. The panels are placed so as to provide optimal heating should be directed. Several examples are shown below layout.