Exchanger for cooling hot primary air by means of cold secondary air, comprising: - a plurality of channels, referred to as secondary channels, placed one on top of the other and intended for the circulation of said secondary air, each extending in the same direction, referred to as the secondary direction, between an air inlet, referred to as the secondary air inlet, and an air outlet, referred to as the secondary air outlet; and - a plurality of channels, referred to as primary channels, for the circulation of said primary air, each interposed between two secondary channels and extending in the same direction, referred to as the primary direction, which is different from said secondary direction, between an air inlet, referred to as the primary air inlet, and an air outlet, referred to as the primary air outlet, so as to allow heat exchanges between the primary air of said primary channels and the secondary air of said secondary channels; characterized in that said exchanger further comprises: - water circulation channels, each extending adjacently to a secondary channel in said secondary direction in the vicinity of the primary air outlets, between a water inlet and a water outlet, so as to allow this water to be heated by heat exchanges with said flow of primary air of said primary channels; and - water-spray micro-perforated hollow bars, each extending adjacently to a primary channel in said primary direction, between a water inlet, which is fluidically connected to at least one water outlet of said water circulation channels, and water-spray micro-perforations leading toward the secondary air inlets, so as to allow evaporation of the heated water sprayed at the inlet of said secondary channels, which thus helps to cool the flow of secondary air at the inlet of the exchanger. - a plurality of channels, referred to as secondary channels, placed one on top of the other and intended for the circulation of said secondary air, each extending in the same direction, referred to as the secondary direction, between an air inlet, referred to as the secondary air inlet, and an air outlet, referred to as the secondary air outlet; and - a plurality of channels, referred to as primary channels, for the circulation of said primary air, each interposed between two secondary channels and extending in the same direction, referred to as the primary direction, which is different from said secondary direction, between an air inlet, referred to as the primary air inlet, and an air outlet, referred to as the primary air outlet, so as to allow heat exchanges between the primary air of said primary channels and the secondary air of said secondary channels; - water circulation channels, each extending adjacently to a secondary channel in said secondary direction in the vicinity of the primary air outlets, between a water inlet and a water outlet, so as to allow this water to be heated by heat exchanges with said flow of primary air of said primary channels; and - water-spray micro-perforated hollow bars, each extending adjacently to a primary channel in said primary direction, between a water inlet, which is fluidically connected to at least one water outlet of said water circulation channels, and water-spray micro-perforations leading toward the secondary air inlets, so as to allow evaporation of the heated water sprayed at the inlet of said secondary channels, which thus helps to cool the flow of secondary air at the inlet of the exchanger.