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Thermofluidic oscillators

Dr Thomas Smith & Dr Christos Markides

glass model NIFTEThermofluidic oscillators are networks of pipe containing fluids, in which temperature differences and heat flows produce, or result from sustained oscillations. Alternatively, they can be thought of as reciprocating heat engines or heat pumps with 'fluid moving parts'. In many ways, thermofluidic oscillators are similar to analogue electronic oscillators, in which voltage differences and currents produce sustained oscillations in a flow of electrical charge.

Analogue electronics is often taught in terms of the water analogy, in which a resistor is represented by a constriction in a pipe, a capacitor is represented by a tank which fills and empties from the bottom, and an inductor is represented by a long coil of pipe containing fluid with a lot of inertia.

In thermofluidics, the water analogy is applied in reverse. We aim to build known electronic circuits, but from fluid components. Temperature differences and heat flows provide for 'fluidic amplification'.

The best known types of thermofluidic oscillators are thermoacoustic oscillators. These have been in existence at least since the eighteenth century. However they have only recently been applied with any success. Thermoacoustic engines work at high (acoustic) frequencies, over small pressure differences. This makes them well suited to generating power (via a microphone), or providing a cooling effect, but they do not operate over big enough pressure differences to be applied as pumps.

At CUED, we have developed a novel thermofluidic oscillator known as a Non-Inertive Feedback Thermofluidic Engine (NIFTE). The NIFTE is capable of sustaining oscillations across large pressure differences due to its independence from inertia. This means that it doesn't require fluidic inductors (long coils of fluid, or resonators) to create time delays, and can be much smaller than other oscillators with the same power output.

The NIFTE is being commercialised for a variety of heat and mass transfer applications through a spin off company Thermofluidics Ltd. These include a variety of 'low grade heat conversion' applications such as solar powered water pumping, domestic hot water circulation using waste heat, simultaneous water heating and pressurisation, and thermally powered cooling. Whilst a research student, Tom Smith was made L'Oreal - Royal Institution Science Graduate of the Year, 2004 for this work, and subsequently won the Sunday Times 'One Minute Pitch' competition in September 2005.

 

   


Doctor Thomas Smith

Doctor Thomas Smith

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Doctor Christos Markides

Doctor Christos Markides

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Telephone: +44 1223 7 61503
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