Alternating notch configuration for spacing heat transfer sheets

A heat transfer assembly for a rotary regenerative heat exchanger, the heat transfer assembly comprising:

• at least two heat transfer sheets stacked upon one another;
• each of the at least two heat transfer sheets comprising:
• a plurality of rows of heat transfer surfaces, each of the plurality of rows being aligned with a longitudinal axis that extends between a first end and a second end of the heat transfer assembly, parallel to intended flow directions through the heat transfer assembly, the heat transfer surfaces having a first height relative to a central plane of the heat transfer sheet;
• at least one notch configuration for spacing the heat transfer sheets apart from one another, the at least one notch configuration being positioned between adjacent ones of the plurality of rows of heat transfer surfaces, the notch configuration comprising:
• at least one first lobe extending away from the central plane in a first direction;
• at least one second lobe extending away from the central plane in a second direction opposite to the first direction;
• either one or both of the at least one first lobe and the at least one second lobe having a second height relative to the central plane, the second height being greater than the first height;
• and
• the at least one first lobe of a first of the at least two heat transfer sheets engaging the heat transfer surface of a second of the at least two heat transfer sheets and the at least one second lobe of the second of the at least two heat transfer sheets engaging the heat transfer surface of the first of the at least two heat transfer sheets to define a flow path between the at least two heat transfer sheets, the flow path extending between the first end to the second end;
• and
• wherein the at least one first lobe and the at least one second lobe are in a common flow channel and longitudinally connected to one another by a flow diversion configuration defined by a transition region, the lobes being situated in a longitudinal alternating pattern such that the at least one first lobe is longitudinally adjacent to the at least one second lobe, wherein within the transition region, a transition surface connects the at least one first lobe to the at least one second lobe and extends through the central plane.

A stack of heat exchanger sheets, the stack comprising:

• at least one first heat transfer sheet comprising:
• a first undulating surface extending along the first heat transfer sheet and oriented at a first angle relative to a direction of flow through the stack, and
• a second undulating surface extending along the first heat transfer sheet and oriented at a second angle relative to the direction of flow through the stack, the first angle and second angle being different;
• and
• at least one second heat transfer sheet defining a plurality of notch configurations extending along a longitudinal axis that extends between a first end and a second end of the at least one second heat transfer sheet, parallel to intended flow directions, for spacing the at least one first heat transfer sheet apart from an adjacent one of the at least one second heat transfer sheet, the at least one notch configuration comprising:
• at least one first lobe extending away from a central plane of the at least one second heat transfer sheet in a first direction;
• at least one second lobe extending away from the central plane in a second direction opposite to the first direction;
• the at least one first lobe engaging a portion of at least one of the first undulating surface and the second undulating surface;
• the at least one second lobe engaging a portion at least one of the first undulating surface and the second undulating surface to define a flow path between the at least one first heat transfer sheet and the at least one second heat transfer sheet;
• and
• wherein the at least one first lobe and the at least one second lobe are in a common flow channel and longitudinally connected to one another by a flow diversion configuration defined by a transition region, the lobes being situated in a longitudinal alternating pattern such that the at least one first lobe is longitudinally adjacent to the at least one second lobe, wherein within the transition region, a transition surface connects the at least one first lobe to the at least one second lobe and extends through the central plane.