Heat exchanger for two fluids, in particular a storage evaporator for an air conditioning device

A heat exchanger (10) includes at least one header box (12, 14) delimiting a first chamber (42) for a first fluid (F1) and a second chamber (44) for a second fluid (F2), as well as a beam of tubes (16) ending into the header box (12, 14) and comprising at least one first tube (18) communicating with the first chamber (42) of the collecting box (12, 14) and at least one second tube (20) communicating with the second chamber (44) of the collecting box, the first tube (18) being coupled with the second tube (20) to constitute a module (22) allowing a heat transfer between the first tube (18) and the second tube (20). The ends (32) of the first tube (18) is off-set with respect to the ends (30) of the first tube (18), so that such ends (30, 32) can be received in an alternate way in insertion holes (34) of the header box (2, 14), said holes (34) being spaced with a constant step (P).