Tubular heat exchange systems

A heat exchange system includes a first flow passage (404) and a second flow passage (406). The heat exchange system is configured to transfer heat between a first fluid flowing through the first flow passage (404) and a second fluid flowing through the second flow passage (406). The first flow passage (404) includes an inlet header (403), a plurality of tubes (402), and an outlet header (405). The inlet header (403) includes a plurality of header-tube transition portions (602) configured to allow the first fluid to flow from the inlet header (403) and into the tubes (402), the plurality of header-tube transition portions (602) each including a smoothly curved inlet portion (604) and a tapered tube connection portion (903).