Abstract: A heat exchange tube combines an external surface feature, for example having crushed fins and cavities, which can have very high boiling enhancement characteristics, with an internal surface feature, for example having high performing intersecting helices, e.g. “cross hatched” with an intersecting helix angle. The new tube can provide a high performing tube in a shell and tube evaporator that can be relatively smaller, more efficient, and that can use relatively lower refrigerant charge.

Abstract: A heat exchange tube combines an external surface feature, for example having crushed fins and cavities, which can have very high boiling enhancement characteristics, with an internal surface feature, for example having high performing intersecting helices, e.g. “cross hatched” with an intersecting helix angle. The new tube can provide a high performing tube in a shell and tube evaporator that can be relatively smaller, more efficient, and that can use relatively lower refrigerant charge.

Abstract: A brazed aluminum microchannel heat exchanger comprising a stack of alternating tubes and serpentine fins includes an expansion relief feature that accommodates uneven thermal expansion in the heat exchanger. The expansion relief feature provides the heat exchanger with sufficient structural support, at least during assembly, so that components of the heat exchanger can be firmly clamped in compression during a controlled-atmosphere brazing process. In some examples, the expansion relief feature is a gap or sliding engagement between adjacent headers of the heat exchanger. In addition or alternatively, the expansion relief feature comprises one or more slits cut into the serpentine fins after the brazing process, wherein each slit extends generally parallel to the tubes.