90% efficient process air heaters handle 800C

A Hawco product story

Edited by the Engineeringtalk editorial team Aug 28, 2001

The spiral wound wire format of Osram Sylvania Serpentine heaters exposes maximum surface area of the element to the airflow and produces a claimed thermal efficiency in excess of 90%

Fast, clean and efficient heat is a common requirement for many processes, especially where rapid throughput is demanded.

The speed at which a process product can be heated is the key to production efficiency; its control the key to product consistency.

Conduction, convection and radiation are the three forms of heat.

It is the latter two that lend themselves to electric heating technology to produce rapid, almost instantaneous heat, focussed on the precise area of a process or product.

These take the form of process air heaters and infrared radiation heaters.

Industries such as packaging, plastics, semiconductor and printing all use convected or radiated heat at critical stages of their processes.

The more efficient the heat transfer, the faster the process can run.

Raising surfaces up to 800C can be achieved with process air heaters.

Modem air heaters incorporate heating elements that exhibit extremely high heat transfer properties.

The Osram Sylvania Serpentine heaters are a typical example.

Their unique spiral wound wire format exposes maximum surface area of the element to the airflow and produces a claimed thermal efficiency in excess of 90%.

Output temperature is controlled by the airflow rate and power input to the heater.

A very fast thermal response is achieved due to the low thermal mass of process air heaters, but in achieving this, a very fast thermal response temperature sensor and controlling element is essential for optimum temperature control and extended heater life.

Typical applications for air process heaters are high speed poly sealing, high speed heat shrink installations, ink drying, textile cutting and drying, plastic welding and forming and processes involving hot melt glues, heat-activated adhesives and soldering.

Infrared heating, in more recent years, has become an efficient, fast and clean alternative method of producing high process temperatures.

In particular, short wave infrared is capable of producing temperatures in excess of 1000? C within a few seconds.

The heater comprises a tungsten filament lamp and a polished reflector capable of focussing the heat on the process.

Infrared heat specialists, Research Inc manufacture high efficiency reflectors for strip, area, spot and radial heating applications.

The low mass of the tungsten element means instant heat up and cool down.

Equally fast response controlling elements, including phase angle power control, is highly recommended if precise control and extended element life is essential.

Applications for short wave infrared heating in the process industry includes curing and re-glossing of plastic tubing, burning off lubricants and preheating of wires and cables, ink drying, heat shrinking, forming, stress relieving, soldering, and bonding of plastics and metals.

Both methods of producing fast-response process heat require special attention to the methods of control because accuracy and response time are paramount to the quality and consistency of the end product.

With the application of additional control features, it is always possible to create a safe, reliable and trouble-free controlled source of heat as a critical element of a process line.