EnglishIndividual heating elements do not include the entire heating system. In addition to the heating element, heaters include terminals, leads, insulation, packing, sheathing and seals. These heaters come in a variety of forms and configurations to suit specific applications. Listed below are the most common heaters and their applications.
Air Process Heater: As the name suggests, this type of heater is used to heat moving air. An air handling heater is basically a heated tube or duct with one end for the intake of cool air and the other end for the exit of hot air. The heating element coils are insulated by ceramic and non-conductive gaskets along the pipe walls. These are typically used in high flow, low pressure applications. Applications for air handling heaters include heat shrinking, lamination, adhesive activation or curing, drying, baking, and more.
Cartridge heater: In this type of heater, the resistance wire is wound around a ceramic core, usually made of compacted magnesia. Rectangular configurations are also available in which the resistance wire coil is passed three to five times along the length of the cartridge. The resistance wire or heating element is located near the wall of the sheath material for maximum heat transfer. To protect internal components, sheaths are usually made of corrosion-resistant materials such as stainless steel. The leads are usually flexible and both of their terminals are at one end of the cartridge. Cartridge heaters are used for mold heating, fluid heating (immersion heaters) and surface heating.
Tube heater: The internal structure of the tube heater is the same as that of the cartridge heater. Its main difference from cartridge heaters is that the lead terminals are located at both ends of the tube. The entire tubular structure can be bent into different forms to suit the desired heat distribution of the space or surface to be heated. Additionally, these heaters can have fins mechanically bonded to the surface of the sheath to aid in efficient heat transfer. Tubular heaters are just as versatile as cartridge heaters and are used in similar applications.
Band Heaters: These heaters are designed to wrap around cylindrical metal surfaces or vessels such as pipes, barrels, drums, extruders, etc. They feature bolt-on cleats that clip securely to container surfaces. Inside the belt, the heater is a thin resistive wire or belt, usually insulated by a layer of mica. Sheaths are made of stainless steel or brass. Another advantage of using a band heater is that it can indirectly heat the fluid inside the vessel. This means the heater is not subject to any chemical attack from the process fluid. Also protects against possible fire when used in oil and lubricant service.
Strip Heater: This type of heater has a flat, rectangular shape and is bolted to the surface to be heated. Its internal structure is similar to a band heater. However, insulating materials other than mica may be ceramics such as magnesium oxide and glass fibers. Typical uses for strip heaters are surface heating of moulds, molds, platens, tanks, pipes, etc. In addition to surface heating, they can also be used for air or fluid heating by having a finned surface. Finned heaters are seen in ovens and space heaters.
Etched foil heaters: Etched foil heaters can also be called thin film heaters. In this type, the resistive heating material is etched and bonded to a foil, usually made of aluminum. If higher flexibility and tear resistance are required, the base material can also be made of heat-resistant synthetic rubber or thermoplastic polyurethane (TPU), commonly used in flexible heating sheets such as PET electric heating film, FPC electric heating film, and silicone electric heating sheet Mostly etched foil heaters. Besides its flexibility, another advantage is the close spacing of the heating elements. This is the inherent advantage of photochemical etching. Heat distribution with greater heat density can be achieved even in such a small form factor. Compared with traditional wire heaters, its application is more specialized. Etched foil heaters are commonly used in medical equipment, electronics and instrumentation, aerospace and apparel. One side can be lined with an adhesive layer to facilitate installation.
Ceramic Heaters: These heaters use ceramics that have a high melting point, high thermal stability, high temperature strength, high relative chemical inertness, and small heat capacity. Note that these are not the same as ceramics used as insulating materials. Due to its good thermal conductivity, it is used to conduct and distribute the heat from the heating element. Notable ceramic heaters are silicon nitride and aluminum nitride. These are often used for rapid heating, as seen on glow plugs and igniters. However, when subjected to rapid high-temperature heating and cooling cycles, the material is prone to cracking due to thermal stress-induced fatigue. A special type of ceramic heater is PTC ceramic. This type self-regulates its power consumption, which prevents it from turning red.
Ceramic Fiber Heaters: In this type of heater, ceramic fibers are used as an insulator to concentrate the heat to the surface to be heated to prevent system losses. One side of the ceramic fiber mat is wound with resistance wire. This side is bonded to a surface that can be heated to 1,200°C.
