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Infrared quartz halogen heat represents a first class solution to many leisure,
office and industrial heating problems. Infra red heats objects by light, much
like sun light, therefore the air is not heated, so the radiant energy is very
economical such as open areas, high bays, garages, workshops, entrances, and
exists especially in areas where drafts can disperse heat.
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.
Power Switching featuring highly reliable, long lasting, hermetically sealed,
self-renewing contacts.120-240-480Volt 20 Amp, 35 Amp, 50 Amp, 60 Amp, 100 Amp
1 Pole, 2 Pole, 3 PoleDIN Mount. Custom Assemblies
120-240-480Volt 20 Amp, 50 Amp, 90 Amp"2 ms" fuses protect power semiconductors
against short circuits120-240-480Volt Phase Angle or Zero Cross Firing10 Amps
to 1200 Amps
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.
Few materials can be considered for use as reflectors in comfort heating equipment.
They must have high reflectivity of infrared energy; resist corrosion, heat,
moisture; and be easily cleaned.
Aluminum is a common reflector material and must be anodized to provide suitable
reflectivity and withstand the heat levels present in an infrared heater. Gold
anodized aluminum is best suited as a reflector material when the combined factors
of cost, workability and weight are considered. Dirt will accumulate ON the
surface and not IN the chemical composition with the gold. Within the infrared
energy portion of the spectrum, clear anodized aluminum reflectors achieve approximately
92 percent reflectivity. The most highly efficient reflector readily available
is a specular gold plate material, which is rarely used due to the prohibitive
cost of gold. Fostoria uses gold anodized aluminum for reflectors and end caps
in their electric infrared heating equipment to provide the highest economical
reflectivity and durability.
The beam pattern created by the reflector must be emphasized in the heating
design. First the reflector must create a straight vertical line from the heat
source to the work area. This is the pattern centerline. Secondly, the reflector
will converge or concentrate the energy into a choice of wide, medium or narrow
patterns. In the electric infrared comfort heat industry, reflectors are also
designed for asymmetric, symmetric and offset patterns as show below.
Electrical Applications Enamels, including solvent-based, water-based and combination
of the two, are the dominant class of industrial finishes today. Most require
evaporation of solvents and curing at elevated temperatures to polymerize a
cross link of finish, then final cure by oxidation. Fostoria electric infrared
ovens provide the even, mar-proof finish required, in one-third the time of
convection systems. In addition, the ability to control intensity of cure prevents
a "too hard" finish which would result in brittleness. Plastisols
are ultra-tough coatings that are 100% solids. The optimal cure is 30 seconds
to 3 minutes. Two critical considerations make infrared the most effective curing
method. First, as plastisol cures, it emits plasticizer, which vaporizes, smokes
and condenses as a heavy liquor. This material must be collected in a predictable
way to prevent contamination of the part and the process and to allow a thorough
cure. Second, to achieve a fusing temperature, the substrate must exceed the
curing temperature by a specified degree. Both are only possible through the
precise control of heat sources and the oven environment found with electric
infrared ovens, such as those designed and manufactured by Fostoria Industries.
Special Effects such as Hammers and Wrinkles are essentially enamels with a
heavy content of metal flake or powder that separates and "floats"
into a desirable pattern. The wrinkles contain slow-drying oils which separate
from the base coat and require an "interrupted" cure. A 1-10 minute
hold allows the oil to separate. Infrared curing for 3-5 minutes in a Fostoria
electric infrared oven produces the ideal "soft" cure.
Liquid Paint Systems electric infrared process heating equipment is the curing
technology of choice for manufacturers of metal, plastic, and composite parts
using either liquid paint finishes or powder coating systems.Engineers have
designed process heating systems that effectively cure oil finishes, advanced
lacquer finishes, enamels, plastisols and special effect finishes such as wrinkles
and hammers. Oil finishes incorporating solvents or reducers are cured to tack-free
using low temperature infrared; the final cure occurs through oxidation of the
finish. Because such finishes are applied at heavier millages than other coatings,
convection ovens are prone to scorch the paint surface before the area nearest
the substrate had cured. This results in wrinkling of some finishes, uneven
drying, and sealing of the surface before the solvent has been liberated. These
problems are avoided with electric infrared ovens due to infrared's ability
to quickly and evenly penetrate the film, particularly during the initial stages
of the heating cycle.
Advanced lacquer finishes are typically applied in several coats, with drying
between each. Unassisted drying between coats is possible, particularly when
finish quality is not critical. However, unless humidity is constantly low,
moisture in the air will deposit on the surface, causing blushing of the lacquer.
This is repaired through time consuming and costly polishing. Best results are
achieved with a Fostoria electric infrared oven producing a cure in 15 seconds
to 2 minutes for each coat. Highly consistent drying temperatures (between 150
and 200 degrees F. depending upon the individual coating) produce an even finish
and eliminate the blushing problem.
Adhesives - Fostoria Electric Infrared Ovens accelerate the cure rate of adhesives
including acrylics, anaerobics, silicones, epoxies, methacrylates and urethanes.
Often, infrared can improve cure quality and reduce fallout ratios. Where adhesives
are ingested with peroxide-containing photoinitiators, Fostoria infrared ovens
in many cases offer a higher performance, more cost-effective alternative to
UV. Ovens produce a complete and precisely repeatable cure in 30 seconds, and
as short as 1-3 seconds for specialty applications such as medical needle bonding.
Infrared Ovens are engineered to the application, or group of applications.
Short to long wave emitters, varying watt densities and near infinite programmable
control give these systems the highest degree of flexibility. Specific applications
include the cure of surface mount adhesives on printed circuit boards, conformal
coatings and USP adhesives using medical grade items, food packaging, toys,
honeycomb (used in the construction of walls, doors, and partitions) and other
products.
Powder Coating Systems For precise curing for thermoset and thermoplastic powders,
industry has come to rely on Fostoria Electric Infrared Ovens. There are more
than 300 powder formulations in use today. Film thicknesses range from under
1 mil to over 15 mil and the range of colors, gloss and applications is equally
as vast. What these diverse powder formulations do have in common, is near-perfect
compatibility with infrared radiation as a method of curing. Existing convection
ovens are in many cases totally replaced with Fostoria Infrared Ovens. In other
cases existing convection ovens are supplemented with an infrared booster ahead
of the convection line. Infrared can be applied before the powder application
and for primary curing.
A wash cycle always precedes the application of the powder, and removal of
residual water is essential before powder is applied. A Fostoria oven rapidly
brings parts to 225 degrees F (or higher if desired), and evaporates all moisture.
Fostoria ovens can also combine drying and preheating cycles into a single process
when necessary.During primary curing electric infrared offers the advantages
of producing no combustion products to contaminate the curing area, and more
importantly, does not rely on moving air to distribute heat. Air movement will
disturb powder, resulting in uneven curing, and will deposit dirt and other
contaminants on the surface being coated, resulting in rejects.
Reconditioning Semi Truck Wheels Curing of Powder Coated Metals has designed
and tested an 80 KW quartz-lamp infrared oven for a re-manufacturer of semi-truck
wheels. The customer switched from a liquid solvent based paint to powder coating
due to the demand for a more durable finish on the product. Had developed curing
processes for powder coatings before. But the cost, cure time and finish quality
were only part of the customer's concern. They needed the flexibility to cure
many parts in the same oven. So, we designed and tested a "zone controlled"
batch oven with the capacity to cure two wheels at a time. We were not only
able to give the customer the versatility they needed, but at the same time,
we offered a solution that reduced cure time by 20%.
Because the customer has a variety of wheel shapes to cure, the "zone
control" flexibility of infrared was important. The oven was designed with
zone control to redistribute the heat "footprint" and intensity of
the heat to match individual products without delaying production. The additional
benefit of this solution is a reduction in paint contamination because of the
accelerated curing speed and the absence of air movement, which would be necessary
in a convection curing system.
Infrared heaters use a reflective shield to direct radiant heat onto a heated
surface. Common types of infrared heaters include metal-sheathed tubular heaters,
quartz tubes, quartz lamps, gas fired catalytic, flat-faced panels and ceramic
emitters. Infrared flat panel heaters are used to heat objects via radiant heat
transfer. Infrared heater elements are replacement heater elements used with
radiant flat panel heaters and radiant reflective heaters. Replacement elements
are of the same types and configurations used in full heating systems. Infrared
reflective process heaters use a reflective shield to direct radiant heat onto
a heated surface. Many infrared reflective process heaters are so precise that
heat can be directed to pinpoint locations. Infrared reflective process heaters
are used in food service, as well as in a variety of other applications.
Important parameters to consider when specifying infrared heaters are maximum
sheath temperature, maximum AC voltage, watts, and maximum watt density. Maximum
operating temperature is the maximum temperature that the sheath covering the
heater may reach. The maximum sheath temperature does not represent the maximum
temperature that a heated substance may reach. Maximum AC voltage represents
the maximum AC voltage the heater can use. Watts represents the available wattage
available from the heater. Maximum watt density is the amount of wattage, per
square inch, the heater is capable of delivering. Watt density is calculated
by dividing the available wattage by the heated area. Watt density is a good
measure of the heater's ability to quickly heat a substance. High watt density
heaters should not be used with extremely viscous materials, materials that
are not well-circulated, or explosive/volatile materials due to risk of fire.
Most heater types will have a protective sheath that covers the heating elements.
Many heaters will be available with many choices of sheath material. Sheath
material for infrared heaters includes aluminum, brass, copper, iron, nickel
alloy, stainless steel, and steel.
Features commonly found on infrared heaters include cooling options, corrosion
resistance, cryogenic use, explosion proof housing, internal temperature detectors,
UL approval and weatherproof housing. Corrosion resistant infrared heaters are
suitable for use in a corrosive or chemical environment. Infrared heaters with
explosion proof housings have housing designed to withstand explosions, protecting
the materials within. This classification may also include housings, which can
withstand sparking and flames.
The term infra-red boosts the popular misconception of something new and mysterious.
The word radiation is associated with suspicion. Infra-red radiation exists
around us at all times. Any object having a temperature above absolute zero
(-273°C) emits infra-red radiation, including the human body.
FP Flat Panel Infrared Heaters are very efficient infrared heat sources in
that as much as 80% of the applied energy is converted into radiant energy.
Typical ratings are 10-15 watts per square inch. The FP Flat Panel Infrared
Heater's advantage versus radiant elements such as quartz tube, metal sheath
tubular and ceramic is the complete, wide area, uniform coverage provided. A
broad range of standard sizes and ratings can form the modular base of a radiant
heating system. Custom sizes and ratings can also be designed for special or
unique applications. The standard material, Quartz Cloth, a cleanable Black
Glass and extra-durable Stainless Steel emitter surfaces are available. Because
of the rugged construction, FP Infrared Heaters are resistant to shock and vibration.
No reflectors are required, eliminating maintenance requirements. Without insulation,
the overall thickness is 1-1/2" - with insulation, 3". Thermowells
can be installed near the surface for precise control of the sheath temperature.
By controlling the sheath temperature, the wavelength can be matched to the
specific absorption characteristics of the material being heated.
Specifications:
Quartz Cloth, Black High Temperature Glass or Stainless Steel Emitter Surfaces.
Quartz Cloth and Stainless Steel surfaces have a black, high emissivity coating.
Stainless Steel Frame for continuous high temperature operation.
Minimum Frame dimensions allow little interruption in the radiant heat pattern
when two or more panels are mounted together. 5/16" of frame overlaps the
emitter's surface.
Refractory Board with Channels for mounting Resistance Helix.
1-1/2" is standard thickness; 3" thick units include High Temperature
Insulation.
1/4-20 x 1" long Stainless Steel Screw Terminals. Standard position of
terminals
depend on rating of heater. Terminal enclosure available.
10-32 Mounting Studs located in the corners and along the edge as required or
as specified.
Minimum Width - 4"; Maximum width - 24".
Minimum Length - 6": Maximum length - 70".
Standard 5" long, .24" I.D. quartz tube thermowell installed from
the side slightly
off center of the panel. Special thermowells can be supplied.
Type K Thermocouple to monitor or control emitter surface temperature -
ordered separately.
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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
Regions:
England
Avon Bedfordshire Berkshire Buckinghamshire Cambridgeshire Cheshire Cleveland
Cornwall County Durham Cumbria Derbyshire Devon Dorset Essex East Riding of
Yorkshire East Sussex Gloucestershire Hampshire Herefordshire Hertfordshire
Isle of Wight Kent Lancashire Leicestershire Lincolnshire London Manchester
Merseyside Middlesex Norfolk Northamptonshire North Lincolnshire Northumberland
Nottinghamshire North Yorkshire Oxfordshire Rutland Shropshire Somerset South
Yorkshire Staffordshire Suffolk Surrey Tyne & Wear Warwickshire West Midlands
West Sussex West Yorkshire Wiltshire Worcestershire
Scotland
Edinburgh Glasgow The Western Isles The Shetland Islands The Orkney Islands
Borders Central Dumfries & Galloway Fife Grampian Highlands Lothian Strathclyde
Tayside
Wales
Clwyd Dyfed Gwent Gwynedd Mid Glamorgan Powys South Glamorgan West Glamorgan
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