Heat exchange cell comprising: - a containment casing comprising a rear wall and a peripheral side wall, - a helically-shaped heat exchanger comprising at least one tubular duct for the flow of a first heat transfer fluid coiled about a longitudinal axis of the helix (A-A) according to a plurality of coils; said heat exchanger being mounted in said containment casing; - a feeding zone of a second heat transfer fluid, intended for the heat exchange with said first heat transfer fluid, defined in the casing coaxially and internally with respect to said heat exchanger; - a first heat exchange chamber, defined in said containment casing and in which a first heat exchange portion of the heat exchanger is housed, said first heat exchange chamber comprising a first collection chamber of the second heat transfer fluid externally defined with respect to the heat exchanger between a radially outer wall of the first heat exchange portion of the heat exchanger and the peripheral side wall of the containment casing; - a second heat exchange chamber, defined in said containment casing and in which a second heat exchange portion of the heat exchanger is housed, said second heat exchange chamber comprising a second collection chamber of the second heat transfer fluid externally defined with respect to the heat exchanger between a radially outer wall of the second heat exchange portion of the heat exchanger and the peripheral side wall of the containment casing; - a fluid outlet passage from the second heat exchange chamber defined in the peripheral side wall of the containment casing near the rear wall of said casing; wherein said first and second heat exchange chamber (22; 26) are separated inside the heat exchanger by a first separating element comprising a substantially plate-shaped body; wherein said first and second heat exchange chambers (22; 26) are further separated outside the heat exchanger by at least one second separating element, radially extending between a radially outer wall of the heat exchanger and the peripheral side wall of the containment casing, said second separating element being circumferentially extended about the heat exchanger at least at said fluid outlet passage from the second heat exchange chamber so as to define at least one fluid passage between the first and the second collection chambers of the second heat transfer fluid; and characterized in that the heat exchange cell further comprises a pair of axial separator baffles (24a; 24b), axially extending between said second separating element and the rear wall of the containment casing, and configured to separate a first portion of the second collection chamber of the second heat transfer fluid defined upstream of said axial separator baffles (24a; 24b) from a second portion of the second collection chamber of the second heat transfer fluid defined downstream of said baffles. - a containment casing comprising a rear wall and a peripheral side wall, - a helically-shaped heat exchanger comprising at least one tubular duct for the flow of a first heat transfer fluid coiled about a longitudinal axis of the helix (A-A) according to a plurality of coils; said heat exchanger being mounted in said containment casing; - a feeding zone of a second heat transfer fluid, intended for the heat exchange with said first heat transfer fluid, defined in the casing coaxially and internally with respect to said heat exchanger; - a first heat exchange chamber, defined in said containment casing and in which a first heat exchange portion of the heat exchanger is housed, said first heat exchange chamber comprising a first collection chamber of the second heat transfer fluid externally defined with respect to the heat exchanger between a radially outer wall of the first heat exchange portion of the heat exchanger and the peripheral side wall of the containment casing; - a second heat exchange chamber, defined in said containment casing and in which a second heat exchange portion of the heat exchanger is housed, said second heat exchange chamber comprising a second collection chamber of the second heat transfer fluid externally defined with respect to the heat exchanger between a radially outer wall of the second heat exchange portion of the heat exchanger and the peripheral side wall of the containment casing; - a fluid outlet passage from the second heat exchange chamber defined in the peripheral side wall of the containment casing near the rear wall of said casing;