070716 Warmterras Nl

Introduction to Infrared heating principles
Frederic Marrot – Induction training 2005
Philips Special Lighting IR

What is Infrared ?

How to heat an object ? Physical possibilities: 1. Conduction 2. Convection 3. Radiation

Conduction Heat transfer is made through direct contact from the source to the object (receiver). E.g.: boiled eggs in hot water, coffee pot on a warming plate Source (s) Ts: high Receiver (r) Tr: rises

Convection Heat transfer is carried out via flow of liquid or gas, primary heated by a source. E.g. central domestic heating, household oven Tt: low Tt: low Tt: high Source (s) Ts: high Receiver (r) Tr: rises Transfert medium (t)

Radiation Heat transfer occurs via radiation emitted from source at high temperature. Surrounding objects in this area are absorbing the radiation. E.g. the sun, infrared lamps Source (s) Ts: high Receiver (r) Tr: rises

Reaching an object, radiant energy can either be:
reflected,
absorbed or
transmitted (through the material)
Reflection, absorption or transmission of radiant energy by the object depends on:
Infrared heating source specifications such as wavelength / frequency
object properties : colour, thickness, material, surface...
Interactions of radiation with an object

Design for infrared heating system must take into consideration:
the heating source specifications
the object properties
the application features
Design of an infrared heating system can only be made if all above characteristics are known.
Designing an Infrared heating system

UV Visible radiation IR
IR within the electromagnetic spectrum Treatment Eye supporting Warmth/ UV-sensitive functions heat materials transport

The infrared wave band UV radiation Visible radiation IR-A IR-B IR-C 800 nm 0.8  380 nm 0.38  1 400 nm 1.4  3 000 nm 3  10 000 nm 10  3620K 2070K 965 K 290 K Short- Medium- Long-waves

The heating effect is due to the infrared part of the optical spectrum.
Infrared energy comprises of three parts:
- IR-A short - waves,
- IR-B medium - waves,
- IR-C long - waves,
Summary

Classification:
short wave
medium wave and
long wave
emitters are available.

Examples of short wave infrared emitters Incandescent tungsten lamp Halogen lamp

Examples of long wave emitters Metal resistance Ceramic resistance

Spectral power distribution of different IR emitters

Comparison of short, medium, long wave emitters 0.05% 10% 30% 60% 1.5% 20% 50% 28.5% 6% 46% 44% 4% Visible IR-A IR-B IR-C 4.0 µm 2.2 µm 1.2 µm Emission peak 5 mn 30 sec 1 sec Swith ON/OFF time (90% efficiency) 40 % 60 % 92 % Radiant efficiency Fe-Cr-Alalloy coil in closed steel tube Fe-Cr-Alalloy coil in quartz tube Tungsten coil in sealed quartz tube Material Resistance Quartz emitter Halogen lamp Emitter Long wave Medium wave Short wave Infrared waves

Comparison of short, medium, long wave emitters The more the source is hot, the more it emits in the short wavelength. When the colour temperature decreases, the maximum of emission moves towards longer wavelengths Low Medium High Color sensitivity Low Medium High Brightness Hardly not relevant Possible Good focusing recommended Focusing with reflectors Yes, very high Yes No Air draughts sensitivity Convection Radiation and convection Radiation Heating principle 800 K 1 300 K 2 450 K Color Temperature Long-wave Medium-wave Short-wave Infrared-waves

Conclusion – Emitters’ comparison
Infra R ed emitters (heat sources) radiate their energy over a range of wavelengths.
Their spectral power distribution depends on the temperature and emission properties of the radiator.
Medium and long wave emitters (e.g. steel tube and ceramic radiators) have a higher thermal inertia and lower temperature than short wave radiators, like InfraRed lamps.

Benefits of short wave infrared lamps Benefits Features Instant heat > 90% emission within 1 second Clean No emission by products, no pollution Safe Quartz envelope, heat shock resistant Economical > 85% of consumed energy transmitted into infrared heat Fully dimmable Fully controllable accurately (0 to 100%) Possibility to put On/Off switches do not affect life time of the lamps people sensor Low maintenance Long life: 5 000 hours Heat can be focused Same optical properties as light, can be directed by reflectors Compact heater Compact heat source, narrow diameter of lamps

InfraRed halogen lamp
InfraRed Business Line
December 2003

InfraRed halogen lamp Quartz tube Cap base Cable Inert gas + halogen Tungsten filament Exhaust tube Filling tip

Why halogen filling gas ?
Long life time
minimized filament evaporation
Why quartz tube ?
Withstanding high temperatures
Heat shock resistancy
transparent to Infrared radiation
Why tungsten filament ?
Fast time response
Very high melting point of 3400°C
Halogen lamp construction

The halogen cycle: Quartz tube Tungsten filament Halogen molecules Cold part >250°C Hot part > 1000°C

Tungsten-halide molecule formation Tungsten molecule evaporation Tungsten molecule dissociation The Halogen cycle The halogen cycle 1 4 3 2

Burning position
In general, quartz halogen lamps should be used horizontally.
For a vertical burning position and in case of strong vibrations, special lamps - indented lamps - are produced where filament supports are fixed in the quartz bulb and some changes are made to the filling gas.

Tungsten filament
Fast time response
Very high melting point of 3400°C
Compact source
Single coil Coiled coil

Halogen lamp construction : Pinch
Pinch temperature must not exceed 350°C, otherwise
Molybdenum foil starts to be oxidised
Cracks in the pinch : leaky lamp
Oxygen enters in the bulb : short life time

Working temperatures
Pinch temperature:
below 350°C to avoid early oxidation of the molybdenum foil (leakage)
pinch temperature has to be measured with thermocouples fixed by the lamp manufacturers according IEC norms
Tube temperature:
minimum 250°C for the halogen cycle
maximum 900°C for industrial halogen lamps,
maximum 800°C for HeLeN and Stela
to avoid structure change (crystallization)

Response time

Comfort Heating Professional & Patio

Comfort heating
Terraces, patio
Hotel rooms
Barbecues
Churches
Factory workshop
Philips InfraRed lamps are used for in & out-door heating:

Comfort heating
Benefits of halogen lamps:
heat only where needed, when needed
visual and instant response
energy saving
clean and safe, no gas pollution

Comfort heating – the range
For Zone-heating applications, Philips propose:
the Unique non glare HeLeN lamp for professional or outdoor heating
Range HeLeN Shape Straight Power 500W - 3000W Finish HeLeN glare reduction Life time 5.000 hours

HeLeN: Infrared Halogen Lamp Unique Philips solution with high heat efficiency and low glare emission

HeLeN : More compact, better colour rendering. Ruby sleeve lamp HeLeN lamp

How Philips HeLeN Infrared lamps work:
Infrared Halogen lamp :
Special filament design delivering direct heat (short wave)
Quartz tube resistant to heat shock
Special HeLeN coating
Reduce glare
Nice colour rendering
Filter visible light, not the heat emission
Horizontal or vertical burning availability
Various caps
Exclusive solution from PHILIPS

HeLeN : Best Spectral distribution with low glare level

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070716 Warmterras Nl

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