A battery device for a ventilation system

A battery device arranged to be installed in a ventilation system and arranged to extract energy from a flow of air, said battery device comprises:

• a housing arranged to receive said flow of air through a first end and
• at least one conduit arrangement arranged inside said housing to extend in a direction from the first end of the housing to a second end of the housing, whereby said flow of air will pass along the conduit arrangement when said flow of air is received by said housing,
• wherein said at least one conduit arrangement comprises at least a first conduit and a second conduit arranged in a pattern extending horizontally in the direction of the conduit arrangement,
• wherein the first conduit is arranged interleaved with the second conduit, wherein the pattern comprises transport channels and straight sections, the straight sections being arranged horizontally and in a first direction relative the flow of air,
• wherein the at least a first conduit and a second conduit are arranged in a bent pattern extending in the direction of the bent conduit arrangement and at a tilt angle (gamma) being in the range of 5 to −5 degrees relative the direction of the flow of air,
• wherein the bent pattern comprises at least one bent section and a plurality of straight sections, each of the straight sections being arranged substantially horizontally and in a first substantially perpendicular direction relative the flow of air, and the at least one bent section being arranged at the tilt angle.