Apparatus with expandable tube bundle

In an apparatus comprising in combination an elongated bundle of flexible, relatively small diameter, thin walled, hollow, polymeric, tubular elements and a housing means therefor extending the length of said bundle, said bundle comprising a plurality of said tubular elements with open terminal portions and a lateral dimension securing means for the plurality of said tubular elements cooperating with the terminal portions of said tubular elements, said housing means entirely surrounding said elongated bundle and defining a zone for fluid passage around said bundle, said housing having inlet and outlet means and means for securing itself to said lateral dimension securing means in a fluid tight arrangement therewith, the length of said housing is selected and determined by the length of the elongated bundle, the improvement wherein the tubular elements in each bundle are of various lengths that range from 0.1-1.0 inch per foot of bundle length, said tubular elements forming an elongated bundle set in a twisted configuration, said twist amounting to from 1.degree.-25.degree. per foot of bundle length as measured by the angle of turn that the tubes in one terminal portion of the bundle are to the tubes in the other terminal portion the tube bundle having a length 0.5-5% greater than the housing length, said tubular elements passing through holes in circular spacers positioned substantially perpendicular to the tubular elements, having a cross sectional area substantially equal to the inside cross sectional area of the housing, further including a plurality of holes through which a portion of said tubular elements pass and an area of 20% or more of the inside cross sectional area of the housing defining one opening through which a portion of said tubular elements pass, the number of tubes passing through each hole or the opening ranging from 1-100, means for positioning said spacers at intervals of from 6-30 inches apart and wherein each spacer is rotated from 45.degree.-315.degree. C. with respect to the adjacent spacers.