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This page is for catalytic infra red heater
| catalytic infra red heater |
This page is for catalytic infra red heater |
Tel: 01536 525136Fax: 01536 481569infraredheater@rackett.freeserve.co.ukthe homepage is a resource for people looking around for the most efficient gas fired infrared heater . the homepage 's survey of the main gas fired infrared heater sites in the UK shows where you can get the most efficient price and gives you most of the sites you might want to visit for the most easiest to use gas infrared heater . |
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What is the life expectancy of the ceramic emitter?Answer: The ceramic emitter is guaranteed for 1 year against burnout!! Typical life expectancy is in excess of 10,000 hours. What is the average surface temperature and associated peak wavelength that the ceramic emitters emit?Answer: Like all infrared sources the Salamander emitter does not emit one single wavelength but a range of wavelengths. The peak wavelength emitted is dictated by the surface temperature of the emitter which can easily be controlled using closed loop or open loop control. In reference to Planck’s Law, a heater will emit a range of wavelengths which is only dependent on the surface temperature of the emitter. What precautions/warnings are there with ceramic heaters? Answer: As with any electrical heaters there are important warnings to consider: Hazard of fire: Do not mount emitters/projectors near combustible materials or within a hazardous area. Hazard of electrical shock: Disconnect power before servicing emitters or projectors. All electrical wiring must be done in accordance with local electrical codes by a qualified service technician. Hazard of severe burns: Emitters and projectors operate at high temperatures. Do not operate emitters at voltages in excess of rated voltage or at a surface temperature greater than 1292 °F (700 °C). What makes your ceramic heaters better than your competitors?Answer: Our lead wires are constructed of 14 strands of 29-gage wire, the heaviest
in the industry. Why are ceramic heaters a good choice?Answer: Ceramic heaters are 96% infrared energy efficient, leading all other types
of infrared emitters. Can I use ceramic infrared heat for preheating or as a booster?Answer: Definitely. Due to the nature of infrared heat it’s very easy to have various zones within an oven. A forced air convection oven is almost impossible to zone within the same heating chamber. How flexible are infrared ovens?Answer: Ovens constructed with the new panel allow for continuous reformation. The 12 inch by 12 inch building blocks can be rearranged, added to or deleted from to change sizes, zoned together or separately, and always on hand to meet any rising job shop need. How much maintenance is required for a ceramic infrared oven?Answer: A well built oven is virtually maintenance free. Due to the heat sensitive Salamander logo, elements can be visually checked to see if all are working. The corrosion resistant elements can be wiped free of any dust or impurities. What is normal delivery for a ceramic infrared oven?Answer: Due to the price savings and convenience of the panel, custom built panels are no longer the norm. Typical delivery times for complete CRP panels is 3 weeks. Small orders may be available for immediate shipment.
General Infrared Questions: Does infrared radiation heat the air?Answer: Water vapor and carbon dioxide particles in the air will absorb infrared radiation. Typically, however, the amount of infrared energy absorbed by the carbon dioxide and water vapor are negligible. Does short-wavelength infrared penetrate more than medium and long-wavelength? Answer: This can be true in some cases but not universally. It is important to know the absorption characteristics of the material being heated over the entire Infrared spectrum when selecting the most appropriate type of emitter. Are IR ovens effective in heating only flat surfaces? Answer: Flat surfaces are ideally suited to heating by IR radiation. They can be heated rapidly and effectively in an IR oven. However more complex, three dimensional shapes can also be heated in IR ovens. Three-dimensional parts can be rotated so that all sides are evenly exposed to radiation as they pass through the oven. The heating rate can also be varied from zone to zone to allow sufficient soak time to heat internal regions of a part. Is an electric infrared oven more expensive to operate than a gas fired infrared oven? Answer: In comparing basic utility costs, an electric infrared oven will be more expensive than gas in most areas. However, the overall efficiency of an IR oven should be measured in terms of production capacity and quality. An electric infrared oven has the capability of producing 37.5 w/in2. A gas fired catalytic system can produce only 11.8 w/in2. Therefore, an electric infrared oven can produce up to three times the amount of product than a gas fired catalytic system. Also, the flexibility and ease of controlling an electric infrared oven with unlimited zoning capabilities creates an environment continuously and consistently producing quality parts. |
the homepage is a website that can help you find a catalytic infra red heater . |
Heat transfer Heat transfer is the process of heat energy flowing from a source at a high temperature to a load at a lower temperature. The three forms of heat transfer are conduction, convection, and radiation (infrared.) Conduction occurs when there is a transfer of heat energy due to a temperature difference within an object or between objects in direct physical contact. Convection is the result of a transfer of heat energy from one object to another via a moving fluid or gas. Radiation heat transfer can occur by infrared, ultraviolet, microwave and radiowaves. Infrared (electromagnetic radiant infrared energy) is the transfer of heat energy via invisible electromagnetic energy waves that can be felt as the warmth from the sun or a downwind fire or other hot object. Electromagnetic Energy Infrared rays are part of the electromagnetic spectrum:
Infrared energy travels at the speed of light without heating the air it passes through, (the amount of infrared radiation absorbed by carbon dioxide, water vapor and other particles in the air typically is negligible) and gets absorbed or reflected by objects it strikes. Any object with a surface temperature above absolute zero, - 460 ° F ( -273 °C) will emit infrared radiation. The temperature of the object as well as its physical properties will dictate the radiant efficiency and wavelengths emitted. Infrared radiation can be compared to radio waves, visible light, ultraviolet, microwaves, and x-rays. They are all electromagnetic waves that travel through space at the speed of light. The difference between them is the wavelength of the electromagnetic wave. Infrared radiation is measured in microns (mm) and starts at .70 mm and extends to 1000 mm. Although the useful range of wavelengths for infrared heating applications occurs between .70 mm to 10 mm.
What Exactly is Infrared Heat? Infrared heating is the transfer of thermal energy in the form of electromagnetic waves. True infrared heat should have one common characteristic: that the transfer of heat is emitted or radiated from the heated object or substance. The source emits radiation at a peak wavelength towards an object. The object can absorb the radiation at some wavelength, reflect radiation at other wavelengths, and re-radiate wavelengths. It is the absorbed radiation that creates the heat within the object.
Infrared heating varies by efficiency, wavelength and reflectivity. It is these characteristics that set them apart and make some more effective for certain applications than others. Varying levels of efficiency are possible within IR heating and often depend on the material of the heat source. The basic measure of efficiency lays in the ratio between the energy emitted and the energy absorbed, but other considerations may affect this measurement. One is the emissivity value of the heat source as based on the perfect 'black body" emissivity level of 1.0. Ceramic heaters are capable of 90% or better emissions as opposed to the lower values of other heater substances.
The useful range of wavelengths for infrared heating applications fall within the range of 0.7 to 10 microns (mm) on the electromagnetic spectrum and are termed short-wave, medium-wave or long-wave. The medium to long range wavelengths are most advantageous to industrial applications since almost all materials to be heated or dried provide maximum absorption in the 3 to 10 mm region. Energy from an infrared heat source that also emits light (short-wave) will typically emit 80% of its energy around the 1mm wavelength, where as the ceramic infrared heater emits 80% of its energy around the 3 mm wavelength.
The emission efficiency of the infrared heating element itself is not enough since they are used within a fixture. The reflectivity of the fixture greatly contributes to the overall efficiency of the heater. Salamander elements are housed within the effective combination of an stainless steel reflector.
Types of Electric Infrared Heaters Some of the types of industrial electric infrared heaters are ceramic elements, quartz tubes and lamps, quartz emitters, flat faced quartz, glass and metal panel heaters.
Comparing Infrared HeatersRadiant Efficiency of Various Heating Elements
Ceramic Heaters are the highest at 96% efficient in converting electricity into
infrared heat. When comparing all the different types of heaters on efficiency,
life expectancy, zoning ability and other factors, ceramic elements and quartz
tubes are the preferred heaters, especially for complex sheet-fed thermoforming
applications. Metal sheathed tubulars have a low initial cost but rate low in
all areas except durability.
In Search of the "Best" Heater The day has still not arrived when we can manufacture a heater that can do all things. That’s why a knowledge of the strengths and weaknesses of all types of heaters is the only way to successfully make choices for specific applications. The four major heat types to be considered are: metal sheath, quartz tube, quartz lamp, and ceramic.
Similarities in the above types of heaters are less important than the differences. They are all good heaters, depending on what application they are being used in. It is also important to realize that some applications may benefit most from using a combination of heat types. By having a good knowledge of the differences of the various heat types, and using a simple process of elimination, it can be easy to match the best heater for an application. Using a combination of heaters can be a little more difficult and in considering it, each phase of the process should be evaluated by the same criteria.
The following are simple explanations of the most appropriate usage for the four heater types: Metal-sheath elements- are best used for convection heating needs, such as ovens. They are rugged, cost effective for the application, and efficient. For example, metal-sheath elements can be found in every electric household oven.
Quartz tubes- are best used for radiant applications that need instant on, instant off, such as heat sensitive materials that may have to linger in a heat source.
Quartz lamps- are also instant on and off but made in extremely high watt density. These are effective for high speed production processes.
Ceramic elements- are best used for processes requiring an even, gentle heat and where there is a need for zone control.
Wavelength and emissivity value of the material being heated are also essential for heater selection. Though emissivity charts should be used with specific formulas to calculate the wavelength requirements, a simple generality is "the hotter the heating element, the shorter the wavelength." The absorption rate of the material would then need to be considered as to which wavelength would be appropriate. Another generality is "the higher the absorption, the longer the wavelength requirement." A more detailed explanation of wavelength and emissivity will be covered in a future newsletter.
Properties of Infrared Radiation
There are several physical laws that explain the properties of infrared radiation. The first and probably most important of these laws states that there is a positive relationship between radiant efficiency and the temperature of an infrared source. (Radiant efficiency is the percentage of radiant output from a heat source).
The proportion of energy transmitted from a heat source by each of the three heat source methods is dependent on the physical and ambient characteristics surrounding the heat source, and in particular the source's temperature.
The Stefan-Boltzman Law of Radiation states that as the temperature of a heat source is increased, the radiant output increases to the fourth power of its temperature. The conduction and convection components increase only in direct proportion with the temperature changes. In other words, as the temperature of a heat source is increased, a much greater percentage of the total energy output is converted into radiant energy.
The wavelength of infrared radiation is dependent upon the temperature of the heat source. A source temperature of 3600 °F will produce a short-wave of approximately 1mm, while a source temperature of 1000 °F will produce a long-wave of approximately 3.6 mm. The wave-length dramatically impacts the intensity of radiation at the subject.
A critical function of the wavelength of infrared radiation is its ability to penetrate an object.
The penetration of infrared energy is a function of its wavelength. The higher the temperature the shorter the wavelength. The shorter the wavelength, the greater its penetrating power. For example, a tungsten filament quartz lamp operating at 4000 °F., has a greater ability to penetrate into a product than a nickel chrome filament quartz tube operating at 1800 °F.
There are certain advantages gained in industrial processing by using the penetrating capabilities of short-wave infrared. For example, short-wave radiation can be effectively used for faster baking of certain paints since the infrared radiation penetrates into the paint surface and flows out solvents from within. Conventional drying methods can form a paint skin and trap solvents. Some other applications of short-wave infrared include heat shrinking, water dry-off, and preheating of objects prior to further processes.
Color sensitivity is another characteristic of infrared radiation that is related to source temperature and wavelength.
The general rule is the higher the temperature of the source, the higher the rate of heat absorption of darker colors. For example, water and glass (which are colorless) are virtually transparent to short-wave radiation, but are very strong absorbers of long wave radiation above 2.
Another characteristic of infrared that is not dependent upon temperature or wavelength is response time. Sources with heavier mass take longer to heat to the desired temperature. For example, a tungsten filament has a very low mass, and achieves 80% radiant efficiency within microseconds. A coiled nickel chrome filament in a quartz tube acquires 80% of its radiant efficiency in approximately 75 seconds and metal sheathed rods require approximately 3 minutes.
The rate of response becomes an important consideration especially when applying infrared to delicate and flammable materials.
Infrared radiation is electromagnetic radiation which is generated in a hot source (quartz lamp, quartz tube, or metal rod) by vibration and rotation of molecules. The resulting energy is controlled and directed specifically to and on people or objects. This energy is not absorbed by air, and does not create heat until it is absorbed by an opaque object.
The sun is the basic energy source. Energy is projected 93,000,000 miles through space to heat the earth by the infrared process. This infrared energy travels at the speed of light, and converts to heat upon contact with a person, a building, the floor, the ground or any other opaque object. There is, however, no ultraviolet component (suntanning rays) in Electric infrared.
Electric infrared energy travels in straight lines from the heat source. This energy is directed into specific patterns by optically designed reflectors, Infrared, like light, travels outward from the heat source, and diffuses as a function of the square of the distance. Intensity, therefore, would decrease in a proportional manner. So, at 20’ from the heat source, intensity of the energy concentration is ¼ the intensity developed at 10’ distance.
For comfort heating, there must be reasonably even accumulated values of heat throughout the comfort zone. Proper mounting heights of the individual heaters, fixture spacing, reflector beam patterns, and heat source wattage must be specified to generate the proper heating levels at the task area. The amount of heat delivered is also adjusted by input controllers or by thermostats which respond to surrounding temperature levels and provide ON-OFF or PROPORTIONAL inputs.
1 ) HEATS PEOPLE WITHOUT HEATING AIR Infrared travels through space and is absorbed by people and objects in its path. Infrared is not absorbed by the air. With convection heating the air itself is warmed and circulated ... however, warm air always rises to the highest point of a building. With Infrared heating, the warmth is directed and concentrated at the floor and people level where it is really needed.
2) ZONE CONTROL FLEXIBILITY Infrared heating is not dependent upon air movement like convection heat. Infrared energy is absorbed solely at the area it is directed. Therefore it is possible to divide any area into separate smaller zones and maintain a different comfort level in each zone. For example, Zone A, with a high concentration of people, could be maintained at a 70 degree comfort level while at the same time Zone B. a storage area, could be kept at 55 degrees or even turned off completely.
3) STAGING Another unique control feature of electric infrared that increases comfort conditions and saves energy consumption is staging. Where most systems are either "fully ON" or "fully OFF" the staging feature also allows only a portion of the equipment's total capacity to be used. For example, a two- stage control would work as follows: During the first stage, one heat source in every fixture would be energized. During the second stage, two heat sources in every fixture would be energized. For further control sophistication, a large area can be both zoned and staged. These systems, then, allow a more consistent and uniform means of maintaining a specific comfort level and avoid the "peak & valley" syndrome.
4) REDUCED OPERATING COSTS The previous statements are advantages in themselves; but combined they account for an energy/fuel savings of up to 50 percent. Actual savings will vary from building to building depending on factors such as insulation, ceiling height and type of construction.
5) INSTANT HEAT Electric infrared produces virtually instant heat. There is no need to wait for heat buildup. Turn the heaters on just prior to heating requirements.
6) NEGLIGIBLE MAINTENANCE Electric infrared is strictly a resistance type heat. There are no moving parts or motors to wear out; no air filters or lubrication required. Periodic cleaning of the reflectors and heat source replacement is all that will be required.
7) CLEAN Electric infrared, like other forms of electric heating, is the cleanest method of heating. There are no by-products of combustion as with fossil fuel burning units. Electric infrared adds nothing to the air nor takes anything from it.
8) SAFE UL listed
No open flame
No moving parts to malfunction
No fuel lines to leak
No toxic by-products of combustion
9) EFFICIENT All Electric Heaters convert energy to heat at 100% efficiency.
In electric Infrared heating for ‘Total Area’ heat design, the actual fixture layout parallels closely the approach used in a general lighting system, but without as much permissible latitude. The allowable range of air temperature people accept as "comfortable" is very limited. Deviations of a few degrees from the preferred comfort temperature greatly affect a feeling of being too warm or too cold. For this reason, assumptions or rough approximations of critical factors in an indoor total heating system design must be minimized.
In electric infrared heating systems, it is important to know that air temperatures can be lower than temperatures with conventional heating systems, while giving the same degree of comfort to the occupants. The reason is that much of the heating affect on the occupants comes directly from the radiant energy produced by the heating elements. The infrared system also makes the temperature of the floor and surfaces higher than the surrounding air temperature.
The function of an electric infrared ‘Total Area’ heating system is
to supply the right amount of heating where needed to maintain a constant desired
comfort level. An effective heating system brings the room surfaces and air
up to temperature and holds them constant despite changes in outside air temperature
or variations in heat losses. If the infrared equipment is carefully selected
and properly installed (to project heat downward in a uniform distribution pattern
over the floor area), excellent ‘Total Area’ heating efficiency can
be expected.
The method of transferring and directing the infrared energy to the work level is an important factor in the heating design and will greatly affect the efficiency of the heating system.
Reflectors are used to direct the radiant energy from the source to the work area. The higher the efficiency of the reflector, the more radiant energy will be transferred to the work level. The reflector efficiency is influenced by the reflector material, its shape and contour.
One method of measuring the efficiency of the material is by the emissivity factor. Emissivity is defined as the ratio of the amount of energy given off by radiation from a perfect black body; and is equal to the rate that material will absorb energy. The lower the emissivity number the less the material will absorb; hence the better the reflectivity of the material.
We custom fabricate infrared heating panels with ceramic heaters. While manufacturing ceramic infrared heaters is a constant part of our business routine, adapting the heaters, either by configuration or by physically creating custom products with the ceramic medium to unlimited known and unknown applications, is what Infrared Internationale and its representative agents and distributors do best. We pledge never to remain satisfied with the status quo when improvements are needed and challenges continuously presented. Our product is manufactured based on the specifications of our customers needs. It is you who determines the effectiveness of our product and advancing technology which dictates our progress and direction.
Our engineering services are available and we welcome and encourage you to consult with us in helping you to create the perfect solution for your infrared heating needs. We can typically provide conceptual drawings and quotes on a custom infrared emitter or panel within days of a customer request. All information received from a distributor or the distributor's customer will be kept strictly confidential.
The versatility and flexibility of the ceramic medium and subsequent infrared products allow for their adaptability to countless applications. Infrared Internationale, through its representative agents and distributors, provide engineering, laboratory testing, custom fabrication, and system design.
What is the optimum distance from the ceramic heater source to the load?Answer:
The source should be as close as practically possible to the load. However,
the source should be far enough away from the load so that the infrared radiant
pattern from each emitter (in a panel) will overlap each other. Some materials
are very heat sensitive and if the radiant patterns of the heat source do not
overlap at the load, "striping" can occur. The distance from the source
to the load is dependent on the spacing between emitters. emitters that are
spaced 1" apart would require a distance to the load of 8" to achieve
even heating of the load.
What are the radiant emission patterns of ceramic emitters?Answer: The question
often arises about the different shapes of ceramic heaters. Ceramic heaters
are manufactured with three basic emitter faces: convex, concave as in the,
and flat.These different shapes create three different emission patterns. Radiant
energy is emitted from all objects at different levels of intensity. This energy
comes off all surfaces at true right angles. The convex shape gives off a "wide
area" pattern which is desired in comfort heating or other applications
that require dispersed heating. A concave surface will emit a "concentrated"
pattern which is highly effective when zone heating is desired as well as radiant
heating in general. The flat surface will produce a "uniform" pattern
for even heating at a close proximity between the emitter and the material to
be heated. Examples of this are sheets of plastic or curing of surfaces. When
dealing with new applications the emission pattern needed is usually easily
determined, but in retrofit applications elements should not simply be replaced
without questioning whether there has been a change in application. Can ceramic
infrared heaters be used to heat metals?Answer: If you apply infrared radiation
to a polished metal surface, almost all of the incident infrared radiation will
be reflected from the metal surface. In this condition the metal will never
come up to the temperature required. The only way to effectively heat metals
using infrared radiation is to increase the emissivity of the metal surface.
Painting the surface of the metal will increase its surface emissivity value
to 90%. Now the paint will absorb 90% of the incident infrared radiation and
will transfer this heat to the metal via conduction.
How can you tell if a Salamander ceramic emitter is working? Answer: This heat transfer will turn black when the emitter is "on". When the emitter is "off" this heat transfer will return to its original red color.
What type of controls are required to control the temperature of the ceramic emitters?Answer: Since the ceramic emitters are relatively slow responding ( 8 minute warm-up time required to achieve operating temperature ) closed loop control with an inexpensive proportional control and contactor will control the heaters typically between +/- 2 ° F. Percentage timers and SCR power controls can also be used very effectively.
A lot has been said about the zoning capability of ceramic heaters. In fact, zone control is one of the biggest advantages to using ceramic elements over other forms of infrared heaters. Control products are available, and many are stocked at Mor Electric, and can be purchased along with the ceramic elements as well as other accessory products needed to create a "system".
The control of ceramic emitters can be one of two types: non-feedback or feedback. It is important to be able to differentiate between these two control systems in order to best advise your customers on the products available to them.
Non-feedback can control the temperature by two different methods. The first controls by time using a percentage-on/percentage-off duty cycle. When the timer is set for the on/off time cycle, the overall temperature of the emitter will stabilize. This can be done with either a mechanical timer or with a computer control.
The second method of non-feedback is through voltage control. In this application, a manual potentiometer control, or computerized control regulates the amount of voltage the emitters are receiving, thus controlling the temperature.
With Feedback control, a thermocouple is used to either measure the temperature of the element’s coil or, more accurately, the surface temperature of the element. A type K thermocouple is most universally used because of its 0-2000° F. temperature range and because it is able to be cast into the emitter where it measures the actual internal element temperature. If a Type J thermocouple is desired, in the case of low temperature applications, it must be potted into the element after firing, resulting in the measurement of the center of the emitter which is not as accurate. Infrared Internationale is also the only manufacturer to provide an interchangeable thermocouple in Type J or K. When inserted into a requested thermocouple well, it too will accurately measure surface temperature.
A feedback signal can also be created with a non contact infrared sensor that can sense the emitters or product temperature.
As the temperature of the element changes, the thermocouple creates a millivoltage which is sent back to a temperature controller. The controller then converts the millivoltage into a temperature reading. There are varying ranges of temperature controllers available from a simple on/off, non-indicating controller to a sophisticated digital PID control with ramp soak programming, smart tuning, etc.
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Long wave is least sensitive to colour and is readily absorbed by water.Medium wave is also insensitive to colour and readily absorbed by water and many plastics and paints.Short wave is more penetrating than Long wave and is good for heating metals, but can pass through clear materials.
Infrared radiation is being developed as a non-contact alternative for hot plate welding. The infrared radiation is often supplied by high-intensity, quartz, heat lamps, producing radiation with wavelengths around 1 micron. When this radiation is applied to a polymer, melting occurs. In one mode of operation, the lamps are removed after melting has occurred, and the parts are forged together, as with hot plate welding.
Infrared is particularly promising for higher melting polymers since the parts do not contact the heat source. The causes of stringing and/or joint damage are not present. A recent report (2) indicates that infrared welding of a glass-reinforced polymer (polyethersulfone) results in exceptionally high weld strengths (Weld Factor = 80+%) that are not achieved with other welding processes.
Another potential advantage of infrared welding is speed. Infrared radiation can penetrate into a polymer and create a zone of melt quickly. By contrast, hot plate welding involves heating the polymer surface and relying on conduction to create the required melt zone. As might be expected, however, the depth of penetration depends on many factors, and it varies strongly with only minor changes in polymer formulation. Consistent infrared welding is likely to require very close attention to batch-to-batch polymer uniformity.
Like the sun, it's infrared rays
heat the earth, people and objects directly. The energy emitted is safely absorbed
by cool surfaces that warm up, which in turn, release heat into the atmosphere
by convection to raise ambient temperature.Infrared Radiant Heating
Retrofitting convective forced air heating systems with infrared (IR) systems can save as much as 50 percent of the total heating bill. Infrared heating is more efficient for two reasons: it can be directed to heat only occupied space; and it does not heat the air in a space, it only heats people and objects. Infrared heating works best where convective heaters are not practical. Large open bay buildings, such as hangars, workshops, and warehouses, with large volumes of air to be heated and plenty of unoccupied space are good candidates for retrofit.
This TechData Sheet will help activity personnel understand infrared radiant heating, and identify opportunities for energy-conserving retrofit projects.
Technical Background Infrared heat is a radiated form of invisible electromagnetic energy (like light) that directly warms people and objects, without heating the air in between. Infrared heat travels in a straight line, at the speed of light. Air, the medium for convective heat, is a poor absorber of infrared heat, thus infrared heat can be transmitted a long distance with minimum loss of energy to air. Infrared heaters can be aimed, reflected, and focused on a desired area. When infrared energy shines on people or objects, the energy is converted into heat. The heated personnel and objects then become heat sources that transfer heat into the air. Thus, radiant heat works from the bottom up, warming people, floors, and machines first. Radiant energy striking a concrete floor is converted into heat, which is absorbed by the floor. The floor then becomes a heat storage reservoir, retaining heat in the lower working areas of the building. This makes the working level extremely comfortable and heat is not wasted at the ceiling level, as would be the case with a forced air system.
In open areas radiant heat can be directed onto occupied areas. Convective heat warms the entire volume of air in a room starting at the top and continuing until the thermocline reaches the bottom of the room where the people work regardless of which portions of the room are occupied. This accounts for a significant waste of energy.
Distribution patterns for IR heaters vary depending on heater capacity, type, and reflector shape. Determining these design patterns is integral to the design of IR heater systems, which is fairly complicated and best left to the installer. Most dealers provide a site specific design as part of the cost. Over the years, experience has led to many design conventions that are difficult to derive analytically. Chapter 15 of ASHRAE's 1992 Systems and Equipment Handbook outlines a procedure for radiant heater design.
Heater Types The three main characteristics that separate IR heaters are: Fuel source Emitter type Ventilation IR heaters can use electricity, natural gas, propane, or fuel oil to produce heat. This TechData Sheet focuses on gas-fired units since they are the most likely candidates for an energy saving retrofit.
The two most common types of emitters are tubes and refractory materials. Tube IR heaters blow hot combustion gas through a straight or U-shaped tube, which then emits IR heat. These units can be vented to the outside and can take their combustion air from either indoors or outdoors. Tube heaters operate at up to 1,200°F and can produce 60,000 Btu/hr per 20-foot section. The average combustion efficiency is 86 percent. Figure 1 shows a tube heater.
Refractory material emitters can be made of stainless steel, metallic screens, or porous ceramic. Ceramic, high-intensity, or refractory heaters normally operate between 1,600 to 1,800°F (see Figure 2). A 12- by 1-foot heater of this type can provide 100,000 Btu/hr. The average combustion efficiency is 90 percent.
High-intensity heaters are usually configured to vent to the space so adequate ventilation must be provided (about 4 cfm per 1,000 Btu/hr). In the past, when high-intensity heaters were installed in spaces without adequate ventilation there was a noticeable decrease in air quality. For this reason tube heaters have become more popular for indoor applications. The rectangular heaters are often more economical than the tube heaters but really have limited application due to the venting problem. When choosing between the two types of heaters, carefully consider the ventilation of the space and ask the manufacturer or dealer about adapting the rectangular units for external ventilation.
Applications The first characteristic to look for when considering IR heaters is the ceiling height of the space to be heated. Most heaters have a minimum distance from people and combustible materials. Generally, the surface of the heater needs to be at least 8 feet from anything that could be damaged by the intense heat. Fortunately IR heat can be directed with reflectors. In short, any space with a ceiling height of 12 feet or more may be a candidate.
High bay shops are probably the most frequently retrofitted buildings. They have adequate ceiling height, are expensive to heat with convection heaters, and are usually full of equipment and concrete floors, which make good secondary emitters when heated by IR heat.
Small, semi-enclosed areas, such as patios and carports, are also good sites for IR heaters. Convective heat is ineffective and costly in areas where the number of air changes in a space is high. IR heat cost does not increase with the number of air changes. However, IR heaters may not perform as well in drafty or windy conditions. Despite the decreased performance, it is still cheaper to put up windscreens and use IR heat than to heat with convective units in some cases.
IR heat can be used either as a supplemental heat source or to handle the total heating load. Often IR heaters are used on the perimeters of buildings or near doorways as spot solutions to "cold spot" problems. Keep in mind that sometimes IR cannot be effectively used to heat a building by itself. It is common practice to use both IR and convective heat together. In these cases, the convective source will keep air temperatures at 40 or 50°F while the IR sources will provide occupant comfort only. Buildings that are suitable for only IR heat have the highest potential for savings.
As a final note on applications, it should be mentioned that U-tube configuration heaters are more common than straight tube heaters. The U-shaped configuration tends to even out heat distribution better and is less likely to cause hot or cold spots in the space.
Sizing and Costs as mentioned earlier, analytic sizing is a difficult process and is usually not done. More often, manufacturers and dealers rely on rules of thumb derived from experience to decide on appropriate heater size. A summary of those conventions is offered here to give facilities mangers an idea of what equipment will be required. A dealer cost estimate is required for all project submissions.
A common first run sizing method for tube heaters is relatively simple. If the building is 200 feet or less wide, two rows of tubes will be required. The length of each tube is the length of the building divided by two. For example, a building 50 feet by 100 feet would need two tubes, each 50 feet long. Two-hundred feet is the maximum building width that two tubes can accommodate. For a building 200 to 400 feet wide, three tubes would be required, and so on.
Tube heater prices vary but one can expect to pay $900 for the first 10 feet of tube, which contains the burner. Each additional 10-foot section is about £130, these sections will be the emitter only. Prices also vary depending on rated input in Btu/hr. Total capacity required is often estimated by taking 80 to 85 percent of the total building heat loss in Btu/hr. This works for either tube or high-intensity heaters.
A common size panel for rectangular ceramic heaters is 2 feet by 1.5 feet and costs about £400 for a 30,000 Btu/hr unit and about £550 for a 100,000 Btu/hr unit. Some manufacturers calculate coverage area by multiplying the mounting height by two. For example, a unit mounted at 10 feet will cover a 20- by 20-foot area. That is the area the heater will cover. The capacity of the heater will then have to be determined by the desired interior temperature, space conditions, and exterior temperature.
To estimate the labor costs, consider that for either tube or refractory heaters the labor for installation is usually three to four times the material cost. Table 1 gives a summary of heaters and their characteristics. In general, sizing is a function of mounting height, heater dimension, heater capacity, and interior and exterior temperatures. An experienced designer can adjust dimensions and sizes of heaters by raising or lowering the rated capacity of the units. To get an idea of what equipment is necessary to heat a building, use the following procedure: Calculate the building's heat load. The total rated capacity of IR heat should be 80 to 85 percent of the building's heat load. Determine which type of heater is most appropriate based on the space characteristics. Use the area coverage conventions mentioned above to determine the number of refractory heaters or the length of tube required. Use the total IR capacity required and the number of heaters or length of tube to determine the capacity (Btu/hr) of each unit or tube.
The cost of the current heating system is the largest factor affecting the
cost effectiveness of converting to IR heat. The two biggest factors affecting
convective heat in high bay industrial buildings are heating degree days and
building volume. Although the U-values of the walls and the roof are important,
changes in volume or weather usually have a more profound effect on the heating
cost. The payback for converting to IR heat from convective heat in a 200- by
500-foot building with a 40-foot ceiling is almost 2 years. This is based on
the following assumptions: £4.0/MBtu fuel cost 70% existing system efficiency
(including line loss of a central system) A roof U-value of 0.12 Btu/hr x °F
x ft2 A wall U-value of 0.05 Btu/hr x °F x ft2 4,000 annual heating degree
days.
By adjusting these values it becomes clear what has the most effect on payback (see Table 2). Note that the percent change is highest when the building volume changes, followed by a change in the number of degrees days. Wall U-values and boiler efficiencies had a much smaller effect on the payback. The point here is that building volume and weather will most often determine the ideal building retrofit.
These calculations were made using a specific building as a model. Its characteristics are unique and this table is not intended to be a source for payback calculations. However, the data does support the idea of building volume and degree days being the most significant factors in cost effectiveness. To calculate the payback for any building use the following procedure: Calculate the building's annual heating load using ASHRAE methods. Include all losses and internal gains, and multiply this by the fuel cost to obtain the annual heating cost. Contact a few manufacturers or dealers for a cost estimate and an estimated annual fuel cost for IR heaters. Divide the estimated installation cost by the difference between the current cost of heating and the dealer's estimate.
U.S. Army's Fort Knox, KY, has chosen infrared heat as one method to meet energy reduction goals and create savings year after year. During FY 1999, the Directorate of Base Operations Support at Fort Knox achieved an energy savings of approximately 50 billion Btu (48.6 million cubic feet of natural gas) and £194,000. This was achieved by installing 92 percent plus efficient infrared heating systems while improving the environment of occupants. Infrared heat is located above the workspace and exhaust via plastic pipes. Benefits of utilizing high quality infrared heating equipment is the elimination of boiler inspections, smoke stacks, steam traps, and pipe insulation. This concept, with site-adapted designs and sizing, is transferable to most any large high bay building. The payback and reward is even greater in areas where high heat loss is encountered, such as buildings with large overhead doors or poor insulation. Radiant heating uses less fuel than other systems because it heats a building and the people inside in the same manner as the sun heats the earth. The sun does not heat the earth's atmosphere directly; rather its infrared rays strike the earth from 93 million miles away, heating the earth's surface. The surface then acts as a heat reservoir and releases heat into the atmosphere by convection to raise the ambient temperature.
Fort Knox has passed their experience on to nearby Fort Campbell, KY. Fort Campbell has now started to install this radiant heating system in their hangar buildings. Fort Knox chose Co-Ray-Vac®infrared heaters because of the manufacturers experience, quality of materials, the burners which are in series for greater comfort, and combustion gases which are condensed to provide flue temperatures below 200 degrees.
Now with more than 100 buildings heated with radiant heating, Fort Knox is using this type of heat to help reach base energy goals. Because of the principles of infrared heating, the thermostat can be set 5 to 10 degrees F lower with radiant heating. This saves fuel, yet people stay warm and comfortable. This means that radiant ambient temperatures are lower than warm air systems ambient temperatures. Also, air is heated indirectly, so less fuel is needed to maintain warmth at floor level.
Fort Knox has incorporated a thermostat that uses an adjustable photoelectric eye to lower the thermostat setting to 55 degrees whenever the lights are turned down, or at night. This thermostat has removed the headaches of having to reset timers or clocks after every power failure or time change, and teaching occupants how to program thermostats. The estimated savings per year is about £194,000 and more than 50 billion Btu. Most of these savings are a result of work accomplished with Department of Defense Energy Conservation Improvement Program Funds and demand side management funding that was available at the time. All new construction at Fort Knox will include infrared heating where applicable.
This vacuum system bakeout unit was developed to replace or eliminate cumbersome ovens and heater tapes used in high vacuum system bakeouts. The heaters are small, high power quartz lamps that operate on the inside of the vacuum system. These heaters utilize 100% of the radiant heat emitted by the lamps and thus are able to reach bakeout temperatures in a much shorter period of time than ovens or tapes. The internal heat sources reduce the bakeout time required to reach base pressure. The heater elements are securely mounted on standard conflat flanges. Care should be exercised not to touch, damage or coat the lamp because the high heating efficiency could be reduced.
The IR-2000 system INTERNAL HEATER employs 2 separately mounted quartz lamps designed for use inside a vacuum chamber to outgas the system. WARNING: When in operation for a long period of time, enough heat is generated inside the vacuum chamber that the chamber can cause painful burns when touched. Care must be exercised to prevent anyone touching the chamber and causing a burn and/or discomfort.
Setup Instructions: The IR-2000 INTERNAL HEATER is shipped ready for immediate
use. However, the lamp itself is demounted and separately packaged to prevent
damage in shipment. arefully unwrap the quartz bulb. Do not touch the glass
portion of the bulb when installing it in the holder, as a fingerprint on the
glass portion may cause early bulb failure or diminished heating, not to mention
unwanted outgassing.
Carefully raise the upper bulb holder to insert the bulb and prevent the ceramic
ends of the quartz bulb from chipping.
Install the bulb and holder in a 2-3/4" OD x 1-1/2" ID flange on the
system. Be careful that it clears or does not interfere with any equipment inside
the vacuum system.
Install the control unit in a rack panel, or place it in an unobstructed place.
Place the two power leads on the feedthroughs for the heater unit.
The IR-2000 requires 12 amperes when both bulbs are in use. The IR-2000 INTERNAL
HEATER unit is now ready to operate.
With the vacuum pumping system in operation, turn the "Time" knob
to the desired time for heating the system. The exact time will have to be determined
for each system and depends on the outgassing required for system operation.
The timer may be set for 1-12 hours depending on the system bakeout requirements.
For periods of less than 2 hours, turn the timer past 2 and then back to the
desired time.
First turn the power knob well past the intensity desired and then adjust the
power for heating. Full power will decrease the time required to outgas the
vacuum system. As the system warms up and outgasses, the base pressure of the
system will increase.
After the timer shuts off, continue pumping for a period of time as the system
cools down. After cooling, the vacuum system is ready for use.
Additional heating cycles may be needed to completely outgas the vacuum system
and to reach the base pressure required, especially the first time a system
is used. The quartz lamp is rated for 180 hours of service. McAllister Technical
Services cannot guarantee the lifetime of the bulbs, as rough handling or severe
system operating conditions may reduce the lamp service life.
The sun is an example of an infrared heater. It radiates infrared heat waves
through space until these rays strike an object, such as planet Earth. The Earth
is warmed by the sun's infrared waves. The warmed Earth then gives off heat
to heat the air.
Using this same infrared heating principle, we take infrared energy from a man-made
heating element, control it with a reflector as light is controlled, and project
it to the subject to be heated (animals, birds, people, or objects). This infrared
energy is identical to the sun's energy but without the UV tanning rays. It
does no heating until it is absorded by the subject underneath the heater. The
heated subject then gives off some heat to help heat the surrounding air.
BENEFITS Save Energy Why heat the entire building when all you want to do is provide warmth for the animals/birds that are confined in one space. Downgoing infrared rays heat animals, birds, people, objects - not the air around them.
Save Time & Labor Kalglo heaters come complete ready to use, similar to a "shop light". No expensive plumbing and installation costs or necessary routine maintenance as with gas heaters. Save Animals Animals love Kalglo heaters for their large heat patterns and lower intensity heat - not focused in one small spot as with heat lamps. Baby animals/chicks will not bunch or pile on top of each other. New born animals usually have no problem finding the warmth under the Kalglo heater. They remain warm, dry and comfortable for better health and faster weight gain.
Safe, Clean Heat Kalglo heaters have durable metal sheath heating elements,
similar to the elements in an electric oven. No glass tubes or lamps to break
and no open flame. Minimal fire hazard! They do not remove oxygen from or put
moisture into the air as gas heaters do. They emit no UV (ultra-violet) light.
Fuel efficient
Quick heat recovery
Many design options
Environmentally friendly
Easily installed
Reduced heating electricity cost
Comfortable gentle heat
Aesthetically pleasing
Quiet, draft-free heat
Minimal maintenance
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