The Zurich laboratory has already constructed a prototype that feeds the water from the chips into a heat-exchanger.

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At Mach 4 or 5, the air flow would become dangerously hot but this heat exchanger - consisting of a dense and closely-guarded bundle of tiny tubes - would chill things down to a manageable temperature in milliseconds.

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The pre-cooler, also known as the heat exchanger, is made up of a huge number of tubes that use compressed helium to cool the air around it.

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