heat exchanger V2

heat exchanger for liquids with ribs and followed chambers

some theoretical information
https://en.wikipedia.org/wiki/Heat_exchanger

*
*
another versions
[customizable v2.1](http://www.thingiverse.com/thing:1919974)
[followed chambers V2](http://www.thingiverse.com/thing:1917929)
[simple first version](http://www.thingiverse.com/thing:1916301)