Abstract: A fin-and-tube heat exchanger comprises a fin plate, a heat exchanger tube having portions extending through the fin plate, a plurality of fin collars formed in the plate, wherein louvers are provided so as to surround the tube portions except areas nearest to the collars, the louvers are in parallel with one another and project from alternately both surfaces of the plate, the louver which is located at the trailing edge side and at a position near to a central line of the tube bank is longitudinally extended so as to be along the collars and has opposite rising ends extending from the plate slanted toward the corresponding tube portions at an angle of 35 deg or below to the flow direction of the fluid, and the louver which is located at a position nearer to the trailing edge is also longitudinally extended and has opposite rising ends extending from the plate slanted toward the corresponding tube portions at an angle of 35 deg or above to the flow direction of the fluid so that the angle between the rising e

Abstract: A heat exchanger is disclosed, which comprises a plurality of heat-transfer elements (1) placed side by side each of which has more than one through-hole (3) and which are cyclically bent in a generally trapezoidal wave form in the direction of the flow of a fluid, the bends in one heat-transfer element (1 ) being in phase with those in an adjacent heat-transfer element (1) in such a manner that the main stream of said fluid will flow not through the holes in each of said heat-transfer elements (1) but through the passage formed by adjacent heat-transfer elements (1). This arrangement not only provides improved heat-transfer characteristics; it also serves to offer a lighter product because of the presence of throught-holes (3).

Abstract: A heat exchanger is disclosed, which comprises a plurality of heat-transfer elements (1) placed side by side each of which has more than one through-hole (3) and which are cyclically bent in a generally trapezoidal waveform in the direction of the flow of a fluid, the bends in one heat-transfer element (1) being out of phase with those in an adjacent heat-transfer element (1) by one-half cycle in such a manner that the main stream of said fluid will flow not through the holes in each of said heat-transfer elements (1) but through the passage formed by adjacent heat-transfer elements (1). This arrangement serves to provide improved heat-transfer characteristics.