The disclosure relates to a heat transfer assembly for a rotary regenerative heat exchanger. The assembly includes a rotor arranged between at least two separated fluid flow passages passing flow axially through the rotor, where each flow passage is connected to a sector part of the rotor. The assembly further includes a plurality of channels in the rotor for flowing a fluid through the rotor, each of the channels is enclosed by heat transfer and heat accumulating surfaces in the rotor, and the heat transfer and heat accumulating surfaces of the channels are made in a material providing an average axial thermal conductivity less than 100 W/mK arranged to reduce the Longitudinal Heat Conductivity of the rotor.

The disclosure relates to a heat transfer assembly for a rotary regenerative heat exchanger. The assembly includes a rotor arranged between at least two separated fluid flow passages passing flow axially through the rotor, where each flow passage is connected to a sector part of the rotor. The assembly further includes a plurality of channels in the rotor for flowing a fluid through the rotor, each of the channels is enclosed by heat transfer and heat accumulating surfaces in the rotor, and the heat transfer and heat accumulating surfaces of the channels are made in a material providing an average axial thermal conductivity less than 100 W/mK arranged to reduce the Longitudinal Heat Conductivity of the rotor.

A ventilation unit for an air-cooling tower and comprising a freewheel for drawing outside air and for discharging air in the upper portion of the ventilation unit. The freewheel has a rear face and a front face, the freewheel draws the outside air according to the direction of the axis of rotation of the freewheel by the front face and discharges the air radially to the axis of rotation of the freewheel, the ventilation unit being passed through by a drawing passage of outside air and by a discharge passage of air, the discharge passage of air directing the flow of air to the front of the plane formed by the front face. The subject matter also relates to an air-cooling tower and a method for drawing and for discharging air in such a ventilation unit.