Smiths Turns up the Heat in Aerospace R&D

The vision

A next-generation air/gas heater that out-performs predecessors in test situations for heat, pressure, controllability, cost and size.

The mission

Few in the business world will have escaped the oft-quoted phrase: ‘You can’t do today’s job with yesterday’s tools and still be in business tomorrow.’ But for few will it have as much resonance as for those in the intensely competitive commercial aerospace sector.

The race to carry more passengers further, more quickly, with greater fuel efficiency and reduced emissions, is driving research into new materials and technologies dependent on ever-increasing temperature and pressure gas streams.

Historically, for R&D purposes and maintenance tests alike, the aviation industry has heated compressed air or inert gas using sheathed element (‘tubular’ or ‘immersion’) style electric heaters - similar to those found on electric stoves.

While this protective construction is ideal for heating liquids or corrosive gases, the high thermal mass and poor heat transfer between the element and the casing make it very inefficient for heating air, steam or other inert gases. Top temperatures are limited to just 620˚C (1150˚F) and pressure to 21 bar (300 psi), which are no longer adequate for commercial testing needs.

Further, because the internal heater element must operate at extremely high temperatures to overcome the thermal mass of the insulation and alloy sheath, it is costly and challenging to operate, and puts high thermal stress on the heater wire, reducing element life.

An alternative was required to keep the pace of product progress up with customer demand.

The innovation

The breakthrough came in the form of the Speciality Flanged Inline (SFI) heater range from the Tutco SureHeat heating solutions team of Smiths’ Flex-Tek division, which was designed specifically for air and inert gas applications.

Based on the company’s patented and highly scaleable open coil element - ‘Serpentine’ - the innovative technology offers far superior performance over sheathed heaters by allowing the air stream to make direct contact with the heater element, which greatly improves heat transfer.

Consequently, these SFI heaters can ramp up and down at a rate of 25°C per second, reach 815°C (1500°F) and deliver pressure ratings up to 40 bar (600 psi) as standard. In custom designs, this can be intensified at a ramp-rate of 50°C per second to 900˚C (1650˚F), and 207+ bar (3,000+ psi). This responsiveness also makes the temperature easier to control for precision applications.

Serpentine’s higher watt density also allows for a significantly more compact package, as small as 8 cm (3”) in diameter and 61 cm (24”) long. This makes it easier than traditional heaters to install into existing compressed air lines, and to position it closer to the test articles, improving heat retention, convenience, agility and productivity.

The Smiths effect

With such advantages, Smiths high-capacity Tutco SureHeat SFI heaters are quickly becoming adopted by aerospace R&D and maintenance communities alike. Applications are as varied as emissions testing, and compressed air systems that simulate the high-pressure and high-temperature conditions of a turbofan compressor to test the durability of critical components.

The maneuverable heaters are also proving invaluable in the development of lightweight composite materials, which require precision heat for moulding, clean edging and curing adhesives and epoxies.

By providing such tools fit for the future, Smiths is enabling OEMs to develop faster, safer and more fuel-efficient aircraft components, and MROs to confidently test them in order to safely extend aircraft life.