The use and implement boron nitride as an insulator enables the manufacture of heaters whose surface density, or function of heater surface material, exceeds 150 W/cm2.
These so called "high flux heating elements" are used as cartridge heaters for bolts heating or straight tubular elements for forced convection electric heaters or radiation one.
Traditionally hollow bolts are heated by inserting heating elements insulated with magnesia allowing a watt density ranging from 6-15 W/cm2. CETAL technology using BN allows watt density ranging from 35 to 70 W/cm2. Therefore the overall heating power is much greater. Using CETAL bolt heaters insulated with boron nitride (BN) significantly reduce assembly time (tightening) or disassembly (un-tightening).
The heating elements so called "high-flux heating elements" or VHP (Very High Performance heating elements) are the result of CETAL research and development programs in 1986-1987. They have broadened the scope electric heating elements application by using boron nitride (BN) material.
The high flux heating elements consists of a stainless steel tube AISI 321 316 AISI 309 or Incoloy Ø 10, 16 or 19 mm using Boron nitride insulation, that allows a watt density above 150 W/cm2.
The implementation of VHP elements using smooth or corrugated tube can significantly increase heat exchange coefficients. They are therefore particularly suitable for heating at high flow rate liquid or gas up to 1100 ° C within high pressure (300 bar).