Heat-conducting oval pipes in heat exchangers

Heat exchange apparatus comprising a plurality of heat conducting tubes having oval cross sections, polygonal ends with lateral faces, at least two opposite faces of which ends are extended laterally beyond imaginary extensions of walls of the tubes in directions parallel to shortest dimensions of the oval cross sections, the lateral extensions of ends of the tubes forming relatively short joining faces, oriented parallel to longest dimensions of the oval cross sections and other faces of the ends being deformed inwardly in directions parallel to the shortest dimensions of the oval cross sections thereby forming relatively long faces, adjacent tube ends being directly joined at the relatively short joining faces, thereby forming gaps between the tubes, whereby first fluid flows through the oval tubes and second fluid flows through gaps between the oval tubes.

Heat exchange apparatus comprising a plurality of oval pipes having central oval cross sections and rectangular ends, at least parts of which extend laterally outward in directions parallel to shortest dimensions of the oval cross sections beyond imaginary extensions of walls of the pipes and form relatively short joining faces, by means of which the ends of adjacent pipes are directly connected with each other, and other parts of the ends being deformed inward in a direction of longest dimensions of the oval cross sections thereby forming relatively long faces whereby gaps are formed between the pipes, through which gaps, in use, a first fluid flows while through the pipes a second fluid flows, a frame extending around the ends of the pipes, several rows of pipes directly connected at their adjacent joining faces being mounted in the frame in a grid or staggered pattern, the frame being constructed of the same material as the pipes, and said frame or each of a number of elements disposed at the ends of the pipes constituting a thermal strain compensating member for compensating thermal strain at the ends of the pipes due to thermal expansion thereof, in use.

In a heat exchanger, in which a fluid to be preheated is passed in the heat-conducting pipes having oval cross sections and a hot fluid is passed through a gap formed between these oval pipes, whereby causing heat transfer between said fluid in the pipes and said hot fluid in the gap between the pipes, apparatus for gathering and holding ends of plural heat-conducting pipes characterized in radially distorted ends of adjacent oval pipes and flattened portions of the ends which form faces having outward deformed relatively short outward extended joining faces parallel to longest dimensions of the oval cross sections and relatively long faces deformed inwardly and parallel to shortest dimensions of the oval cross sections and the ends of the pipes being gathered, and said joining faces of each pipe abutted and joined with joining faces of other pipes, and the joined ends surrounded with a thermal strain-compensating frame made of the same material as the pipes.