Undulating Heat Transfer Sheets for Cleaner Rotary Heat Exchangers
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Solution Overview
Problem
Conventional rotary regenerative heat exchangers have limitations in heat transfer efficiency and cleaning effectiveness due to uniform surface geometries and lack of adaptability to varying flow conditions, leading to reduced performance and increased maintenance needs.
Innovation Solution
The development of heat transfer sheets with varying surface geometries, including different angles and heights of undulating surfaces and sheet spacing features, which enhance turbulence and compatibility with sootblower jets, allowing for improved heat transfer and cleaning efficiency without the need for joints or welds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform surface geometries are used on heat transfer sheets, then manufacturing is simpler, but heat transfer efficiency and cleaning effectiveness are reduced
Solution Approach 1:
The heat transfer sheet incorporates undulating surfaces with varying angles and heights at different locations. Specifically, the sheet has undulating surfaces extending between adjacent sheet spacing features, with each undulating surface defined by lobes extending at different angles relative to the sheet spacing features. This local variation in surface geometry creates different flow patterns and turbulence levels in different regions, enhancing heat transfer efficiency and cleaning effectiveness without requiring complex manufacturing processes.
2Device complexity
If uniform surface geometries are used on heat transfer sheets, then device complexity is reduced, but cleaning effectiveness and maintenance requirements are worsened
Solution Approach 1:
The heat transfer sheet incorporates undulating surfaces with varying angles and heights at different locations. Specifically, the sheet has undulating surfaces extending between adjacent sheet spacing features, with each undulating surface defined by lobes extending at different angles relative to the sheet spacing features. This local variation in surface geometry creates different flow patterns and turbulence levels in different regions, enhancing heat transfer efficiency and cleaning effectiveness without requiring complex manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The innovative heat transfer sheets achieve higher heat transfer rates with minimal pressure drop and improved cleaning efficacy, reducing maintenance and extending the lifespan of the sheets by maintaining turbulent flow and deeper penetration of sootblower jets.
Implementation Method 1
The lobes of the different undulating surfaces extend at an angle Au relative to the sheet spacing features, the angle Au being different for at least a portion of the undulating surfaces, thereby providing different surface geometries on the same heat transfer sheet
Implementation Method 2
Hot gas is directed through the heat exchanger to transfer heat to the sheets. As the rotor rotates, the recovery gas stream (air side flow) is directed over the heated sheets, thereby causing the recovery gas to be heated.
Implementation Method 3
Hot gas is directed through the heat exchanger to transfer heat to the sheets. As the rotor rotates, the recovery gas stream (air side flow) is directed over the heated sheets, thereby causing the recovery gas to be heated.
Data Source
AI summary
A stack of heat transfer sheets includes one or more first sheet which includes a first undulating surface formed by first lobes that are parallel to each other and oriented at a first angle. The first sheets include a second undulating surface formed by second lobes that are parallel to each other and oriented at a second angle, different from the first angle. The first sheets include a third undulating surface formed by third lobes extending from one or more ends of the first sheet and terminating at an intermediate point between the end and an opposing end thereof. The third lobes are parallel to each other and parallel to the direction of flow through the stack. The stack includes one or more second sheets defining a plurality of sheet spacing features which engage a portion of the first sheet.