Tubular heat-exchanger

In a tubular heat-exchanger of the kind having a plurality of parallel tubes through which a first fluid flows and which are disposed within walls defining a space or chamber through which a second fluid flows around the tubes and generally in directions substantially perpendicular or transverse to the tubes, the improvement comprising the tubes being regularly and evenly distributed around a central axis parallel to the direction of the tubes, the tubes being located within a ring-shaped zone having a cross-sectional area of which the inner diameter is at least 25 percent of the outer diameter, and the heat-exchanger includes means for radially converging the flow of the second fluid to enter and pass through the region defined by said inner diameter and then radially diverging the flow of the second fluid exiting said defined region, said converging-diverging means providing converging and diverging flow within said ring-shaped zone and including two baffle plates each protruding radially into said ring-shaped zone to about said inner diameter from the walls bounding the space or chamber in which the tubes are disposed, the second fluid entering the vicinity of the tubes past one portion of the outer periphery of said zone and exiting past a second portion of the outer periphery different from said one portion.