Heat exchanger

A heat exchanger comprising

• a first pipe having a longitudinal axis, first radially outward fins extending parallel to the longitudinal axis and first radially inward fins extending parallel to the longitudinal axis;
• a second pipe positioned in the first pipe along the longitudinal axis, and having second radially outward fins extending parallel to the longitudinal axis and second radially inward fins extending parallel to the longitudinal axis, the first radially inward fins and the second radially outward fins being interdigitated;
• first and second end caps extending between the first and second pipes at the ends thereof, respectively, the first and second end caps each having a hole inwardly of the circular channels aligned with the inside of the second pipe, the second pipe, the first end cap and the second end cap defining a central passage open at both ends, the second radially inward fins extending into the central passage.

A heat exchanger comprising

• a first pipe having a first cylindrical body, a longitudinal axis, first radially outward fins from the first cylindrical body extending parallel to the longitudinal axis and first radially inward fins from the first cylindrical body extending parallel to the longitudinal axis, the first radially outward fins and the first radially inward fins terminating inwardly of the ends of the first cylindrical body;
• a second pipe positioned in the first pipe along the longitudinal axis and having a second cylindrical body, second radially outward fins from the second cylindrical body extending parallel to the longitudinal axis and second radially inward fins from the second cylindrical body extending parallel to the longitudinal axis, the first radially inward fins and the second radially outward fins being interdigitated and longitudinally coextensive, the first cylindrical body and the second cylindrical body being longitudinally coextensive;
• first and second end caps extending between the ends of the first and second cylindrical bodies, respectively, and having circular channels facing the first and second pipes and receiving the ends of the first cylindrical body and the second cylindrical body, respectively, the first and second end caps being displaced from the second radially outward and the first radially inward fins.