What is radiant heating?

Radiant heating is a non-contact heat transfer method that transfers thermal energy through electromagnetic waves (primarily infrared radiation) to elevate the temperature of objects. Its core characteristic lies in the absence of a medium (such as air or water), with heat being emitted directly from the heat source at the speed of light and absorbed by the target object.

The application of radiant heating in high-temperature atmospheric furnaces for SINOTEST RDL series Creep Testing Machine primarily relies on thermal radiation as a non-contact heat transfer mechanism, enabling efficient and uniform heat transfer under the high-temperature conditions within the furnace.

Theory

A heat source emits infrared electromagnetic waves due to its own temperature, with wavelengths typically ranging from 0.76 to 1000 micrometers, among which the thermal effect is most pronounced in the 0.76–40 micrometer wavelength band.

Electromagnetic waves are not absorbed when passing through air and directly irradiate the surfaces of objects (such as human bodies, floors, or equipment), where they are absorbed and converted into thermal energy.

After the surface of a heated object is warmed, heat is dissipated to the surrounding environment through secondary radiation, forming a uniform temperature field.

Difference from traditional heating methods

Heat conduction: requires direct contact between objects for heat transfer (e.g., boiling water in an iron pot).

Thermal convection: Heat transfer relies on fluid circulation (e.g., air, water) (e.g., heating air from air conditioning systems).

Radiant heating: Independent of the medium, heat propagates linearly in the form of electromagnetic waves, conforming to the inverse square law of light (distance doubled, illuminance reduced to 1/4).

Common Types and Application Scenarios

By energy type:

Electrical thermal radiation: such as infrared heating tubes, electric oven heating elements, and far-infrared heaters.

Gas radiation: Utilizes natural gas or liquefied gas combustion in radiant tubes to generate infrared radiation for heating large spaces such as factories and stadiums.

Typical application:

Industry: Painting and drying, steel heat treatment, food processing

Building: Floor radiant heating, ceiling/wall-mounted radiant heating

Outdoor: Portable gas heating stove, camping grill

Household appliances: Electric oven (primarily relies on thermal radiation for food heating)

Advantage：

Non-contact heating to avoid contamination;

High thermal efficiency (radiant tube system ≥90%)

Suitable for high temperatures (>1000°C), vacuum, or corrosive environments;

Capable of achieving precise zonal temperature control

Limit ：

Modeling with complex furnace geometry requires substantial computational resources;

When used alone, the steam temperature exhibits significant fluctuations with load variations, necessitating its combination with a convective superheater.

Materials are prone to oxidation at high temperatures and require protection with heat-resistant alloys or ceramics.

‌Fun fact: The sun heating Earth exemplifies natural radiant heating—infrared radiation penetrates the atmosphere and directly warms the surface, bypassing the air layer.