Abstract: A heat exchanger is disclosed having a first chamber, a second chamber positioned inside the first chamber, and a third chamber positioned inside the second chamber. The first, second, and third chambers are in coaxial alignment. A first portion of a first helical tube is positioned inside the second chamber and a second portion of the first helical tube is positioned inside the third chamber and a second helical tube is positioned inside the first chamber. The heat exchanger heats a cryogenic liquid to a gas phase using at least three different heat transfer fluids in one contained unit without mixing any of the fluids in the exchanger.

Abstract: A heat exchanger having a plurality of coaxially aligned chambers for providing radiant, thermal heat transfer between a plurality of separately contained fluids within a single unit and a helical tube having at least one portion positioned within at least one of the chambers. A first, second, third, and fourth chambers are in coaxial alignment. The heat exchanger heats a cryogenic liquid to a gas phase using four different heat transfer fluids in one contained unit without mixing any of the fluids in the exchanger, thus reducing the size and cost, while increasing the efficiency of the heat exchanger.

Abstract: A heat exchanger is disclosed having a first chamber, a second chamber positioned inside the first chamber, and a third chamber positioned inside the second chamber. The first, second, and third chambers are in coaxial alignment. A first portion of a first helical tube is positioned inside the second chamber and a second portion of the first helical tube is positioned inside the third chamber and a second helical tube is positioned inside the first chamber. The heat exchanger heats a cryogenic liquid to a gas phase using at least three different heat transfer fluids in one contained unit without mixing any of the fluids in the exchanger.