What Is a Halogen Heater?
A Halogen heater is a generic term for a heater that heats an object by applying electric power to a filament and using electromagnetic waves in the near-infrared to far-infrared regions generated during the heating process.
These heaters use radiation heating and emit red to white light because they include wavelengths in the visible region. They are characterized by uniform heating performance over a wide area and high responsiveness because they do not require a medium for heat transfer.
There are several types depending on the filament type and structure. Demand for lamp heaters has been increasing in recent years due to their high energy efficiency.
Uses of Halogen Heaters
Because of their radiation characteristics, lamp heaters are good at heating large areas uniformly, and are often used for heating flat objects. Typical examples are:
Drying processes in the production of semiconductors and flat panel displays, ink drying for printed materials, and in-line food drying.
It is also used for heating corrosive chemicals that are difficult to heat directly, and for heating equipment and food products.
Because they use near- to far-infrared rays, they are not suitable for heating transparent objects that are transparent to such rays.
Principle of Halogen Heaters
Applying electric power to a filament generates electromagnetic waves in the near- to far-infrared region, and the energy is used to heat an object in a non-contact state.
Filaments made of tungsten, carbon, iron-chromium-aluminum, nickel-chromium (nichrome), etc. are used, and the filament temperature reaches 2500-3000℃ (4,532-5,432°F).
If the filament is in contact with the atmosphere in such a low-temperature range, a rapid oxidation reaction occurs, resulting in wire breakage and thinning, which shortens the life of the filament.
Therefore, they are encapsulated in quartz glass tubes filled with vacuum or inert gas. Because of this structure, long, thin, cylindrical products are common, but halogen lamp heaters in the shape of a bare bulb are also available.
When heating a flat object, multiple halogen heaters must be arranged to ensure that the radiant energy evenly covers the object.
Unlike direct heating or ambient heating, if the shape or structure of the object is such that the radiant energy is blocked, the shadowed area will not be heated, making it unsuitable for some shapes of objects.
Therefore, it may not be suitable for some shapes of objects to be heated.
The object can be heated up to 1500°C (2,732°F), but the element must be set at 1000°C (1,832°F) or higher because the radiant energy is low at low temperatures below 500°C (932°F). The heating temperature of the object can be increased up to 1500°C, but the element must be set at 1000°C or higher because the radiant energy is low at temperatures below 500°C.
Although the energy efficiency is high, the power requirement is high for the reasons mentioned above, so it is not well suited for low-power, low-temperature heating applications.
In addition, if dirt or other contaminants adhere to the quartz tube bulb on the exterior, the dirt will be heated and the temperature distribution on the exterior surface will change significantly locally, which may cause damage.