Counter-flow Heat Exchanger Casting for Fabrication Complexity
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Solution Overview
Problem
The design of single-pass counter-flow heat exchangers with multiple parallel rows of heat exchanging passageways faces challenges in reducing fabrication costs and complexity while maintaining temperature and pressure resistance, particularly in applications like superheaters, reheaters, gas turbine recuperators, and air-cooled condensers.
Innovation Solution
The proposed heat exchanger features a core region with two sets of heat exchanging passageways arranged in a counter-flow configuration, where one set extends beyond the other, with tube plates and a shell structure that includes casting or brazing to form a robust and cost-effective design, allowing for improved temperature and pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple parallel rows of heat exchanging passageways are used in a single-pass counter-flow arrangement, then heat transfer efficiency is improved, but fabrication cost and complexity increase due to drilling and positioning requirements
Solution Approach 1:
The patent merges multiple individual drilling operations into a single casting process. The tube plate with multiple passageway openings is formed as one integrated component through casting, eliminating the need to drill and position each passageway individually. This combining of operations reduces fabrication complexity while maintaining the heat transfer efficiency provided by multiple parallel passageways.
Solution Approach 2:
The patent replaces mechanical drilling operations with a casting process. Instead of using drilling machinery to create each passageway opening individually, the entire tube plate structure with all passageways is formed through mold casting. This substitution of manufacturing methodology significantly reduces fabrication complexity and cost while preserving the thermal performance.
2Manufacturing precision
If traditional drilling methods are used for each individual heat exchange passageway, then manufacturing precision can be achieved, but fabrication cost and time increase
Solution Approach 1:
The patent combines multiple precision drilling operations into a single casting operation. The mold cavity defines all passageway openings and their relative positions in one setup, achieving consistent positioning precision across all passageways without the cumulative errors and time associated with multiple individual drilling and positioning operations.
Solution Approach 2:
The casting process performs the positioning action preliminarily - the mold cavity itself defines and positions all passageway openings before the actual manufacturing of the tube plate. This preliminary formation of the geometry ensures precision is built-in during the shaping process rather than requiring subsequent precision drilling and positioning operations.
3Strength
If tube plates are used to separate plenums, then structural integrity and pressure containment are improved, but manufacturing complexity increases due to integration of multiple components
Solution Approach 1:
The patent merges the tube plate with the core region into a single cast metal component. The tube plate is not a separate assembled part but is integrally formed as part of the core structure during the casting process. This integration maintains the strength and pressure containment capabilities of the tube plate while eliminating assembly steps and reducing overall manufacturing complexity.
Solution Approach 2:
The patent uses a composite manufacturing approach where metal casting combines the structural functions of both the core region and the tube plate into one homogeneous component. The cast metal provides both the structural integrity needed for pressure containment and the geometric complexity of integrated tube plates and passageways simultaneously.
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
This design enhances manufacturing ease and reduces costs while achieving high thermal efficiency and robustness, capable of withstanding pressures over 800 bar and temperatures above 500°C, with effectiveness ranging from 92-98%.
Implementation Method 1
The first fluid at a higher temperature may be passed through one or more first channels or passageways, while a second fluid at a lower temperature may be passed through one or more second channels or passageways. The first and second passageways may be in contact or close proximity, allowing heat from the first fluid to be passed to the second fluid.
Implementation Method 2
The tube plates and the core region including one of a cast metal formed thereabout the heat exchanging passageways or a braze bond formed between the heat exchanging passageways
Implementation Method 3
The tube plates and the core region including one of a cast metal formed thereabout the heat exchanging passageways or a braze bond formed between the heat exchanging passageways
Data Source
AI summary
A counter-flow heat exchanger including a core region and a plenum region. The core region including a first set of heat exchanging passageways and a second set of heat exchanging passageways disposed at least partially therein. A plenum region is disposed adjacent opposed distal ends of the core region. Each of the plenum regions including a fluid inlet plenum, a fluid outlet plenum and a tube plate disposed therebetween. The first set of heat exchanging passageways is truncated and defines a first tube-side fluid flow path in a first direction. The second set of heat exchanging passageways defines a second tube-side fluid flow path in a second opposing direction. Each of the heat exchanging passageways extending from a fluid inlet plenum to a fluid outlet plenum. The tube plates and the core region include one of a cast metal formed thereabout each of the heat exchanging passageways or a braze bond formed between each of the heat exchanging passageways.