Heat exchanger

A heat exchanger comprising:

• a gas path for flowing gas;
• a first plurality of segments arranged in the gas path and arranged to respectively form projections and depressions repeated in a perpendicular direction to a gas flow direction;
• a second plurality of segments arranged in the gas path, arranged to respectively form projections and depressions repeated in the perpendicular direction to the gas flow direction, and located downstream of the first plurality of segments in the gas flow direction;
• a first projection plate arranged in the gas path and projecting from each segment of the first and second plurality of segments;
• and
• a second projection plate arranged in the gas path, projecting from each segment of the first and second plurality of segments, and located downstream of the first projection plate in the gas flow direction in each segment, wherein
• an arrangement of the first plurality of segments and the second plurality of segments allows the gas to flow from two segments of the first plurality of segments adjacent in the perpendicular direction to the gas flow direction to a segment of the second plurality of segments, and
• the first projection plate and the second projection plate of each segment of the first plurality of segments cause the gas flowing into each segment to flow out from each segment while causing rotation in the gas in different directions with respect to a rotational axis in the gas flow direction and then flow into each of two segments of the second plurality of segments adjacent in the perpendicular direction to the gas flow direction.