Heat Exchangers

Our proprietary heat exchanger technology is the most powerful means of cooling air in the world. A pre-cooler of the same weight as a small car (~1 tonne) can remove 400 MW of heat from the air – that’s the equivalent of a small power station. The cooled air enters a compressor like a jet engine, and the pre-cooler allows it to do so at any temperature up to 1,000°C.

What is a heat exchanger?

A heat exchanger exchanges heat between gases or liquids which are at different temperatures. Everyday examples include air conditioning and intercoolers in cars, where pipes filled with cold gas cool the air flowing through. We have developed extremely high performance heat exchangers for a number of different roles in the SABRE engine. While some of the SABRE heat exchangers are tubular, others are manufactured in micro-channel plate configurations. These are being tested in progressively more demanding conditions before being integrated into our test engine.

The Pre-cooler

Our pre-coolers are made from thousands of thin-walled tubes to provide high surface area to low weight. Each tube is joined to an inlet and outlet manifold, which allows coolant to be injected and removed for the cooling process. We're the only people in the world with the heat exchanger manufacturing experience to bond thousands of joints in a single operation, and achieve zero leakage. The joins in our pre-cooler modules are hermetically sealed, meaning that the gas which escapes can be measured by the molecule.

How does a pre-cooler work?

The pre-cooler is a high performance counter-flow heat exchanger consisting of thousands of small diameter tubes, arranged in involute spirals. The air flows radially inwards, whilst the helium coolant is introduced in the bore of the heat exchanger, and flows outwards along the spirals. This arrangement provides very high effectiveness (~95%) with high heat transfer, minimising the size and mass of the heat exchanger.

Pre-cooler Location

The pre-cooler is located between a hypersonic air intake and the engine's turbo-compressor. The air which enters the intake is decelerated via a shock system, converting its kinetic energy into heat - the temperature rises to approximately 1,000°C at Mach 5. The air is then turned through 90 degrees, flowing radially inward through the pre-cooler matrix before returning to the axial direction and entering the compressor.

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