A heat exchange cell for a heating condensing boiler
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Solution Overview
Problem
Existing heat exchange cells in condensing boilers face issues with excessive thermal stress and overheating of the closing flange and gasket due to high temperatures, compromising safety and efficiency while increasing production costs.
Innovation Solution
A heat exchange cell design featuring a sheet metal closing flange with a single-piece construction, a refractory disk, and thermal barriers to maintain the closing door temperature below 85°C, using a polymer container casing and a gasket that does not require high-temperature resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the closing flange is placed in direct contact with the combustion chamber, then the sealing function is improved, but the temperature of the flange and gasket increases excessively causing thermal stress and safety issues
Solution Approach 1:
A thermal barrier component is introduced as an intermediary element between the closing flange and the combustion chamber. This barrier reduces heat transfer to the flange and gasket, maintaining their temperature at acceptable levels while preserving the sealing function. The barrier acts as a thermal mediator that allows the flange to remain in position for sealing without direct thermal exposure.
Solution Approach 2:
The thermal barrier is designed as a simple, cost-effective component that can be easily replaced if needed. It provides temporary thermal protection during operation, sacrificing itself to protect more critical and expensive components like the gasket and flange from thermal damage.
2Reliability
If thermal barriers are added to protect the closing door and gasket from high temperatures, then operating safety is improved, but the device complexity and production costs increase
Solution Approach 1:
Instead of providing thermal protection throughout the entire closing assembly, the thermal barrier is applied locally only where heat transfer occurs - specifically between the combustion chamber and the closing flange. This localized approach provides necessary protection while minimizing added complexity and cost.
Solution Approach 2:
The thermal barrier utilizes materials with low thermal conductivity properties, creating a composite structure that combines the metal flange with a thermal insulation layer. This composite approach provides thermal protection using simple material properties rather than complex mechanical structures.
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 design enhances operating safety and thermal efficiency by reducing the closing door and gasket temperatures, minimizing material usage, and lowering production costs.
Implementation Method 1
transferring heat to the fluid to be heated
Implementation Method 2
heating fluid consisting of the combustion fumes produced in the combustion chamber, which reach the fume collection chamber after passing between the spaces between the helix turns
Implementation Method 3
thermal barriers to maintain the closing door temperature below 85°C
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heat exchange cell (1) for a heating condensing boiler, comprising a heat exchanger (10) comprising at least one tubular pipe (11) adapted to be traveled by a fluid to be heated, helically wound about a helix axis (L-L) according to a plurality of helical coils (12, 13, 14), and defining a free central space adapted to form a combustion chamber (15), ending with a first end coil (13) and an opposite last end coil (14) evaluated along said helix axis (L-L); a container casing (40) containing said heat exchanger (10) mounted therein, comprising a side casing wall (41) arranged radially outside, and about said heat exchanger (10) forming a fume collection chamber (16) radially interposed between said exchanger (10) and said side casing wall (41) adapted to receive combustion fumes (17) generated in the combustion chamber (15) after said fumes (17) have transferred heat to said fluid to be heated in said at least one tubular pipe (11), said container casing (40) further defining a front casing end (45) comprising a casing opening (42) surrounded by an annular casing edge (43) having the center on said helix axis (L-L) wherein a first end coil (13) of said plurality (12, 13, 14) is facing said casing opening (42); an annular closing flange (50) arranged coaxially to said helix axis (L-L) defining a radially outer annular flange edge portion (53) and a radially inner annular flange edge portion (54) with respect to said helix axis (L-L), the radially outer annular flange edge portion (53) being continuously and sealingly coupled to said annular casing edge (43), and the radially inner annular flange edge portion (54) defining a central flange opening (55) for allowing access inside the combustion chamber (15), wherein said closing flange (50) is made of sheet metal and is entirely formed by molding in a single piece, and wherein said closing flange (50) comprises an annular contact portion (56) coaxial to said helix axis (L-L), said annular contact portion (56) being arranged in direct contact and sealingly with at least one corresponding annular portion (13') of the outer surface (13") of said first end coil (13); and wherein said closing flange (50) comprises an annular sealing portion (57) coaxial to said helix axis (L-L); a removable closing door (80) configured to removably close said central flange opening (55) when said closing door (80) is tightened to said closing flange (50) in a closed position, said closing door (80) defining an annular door edge portion (81) configured to be coupled to said annular sealing portion (57) of said flange; wherein said annular sealing portion (57) of said closing flange (50) is arranged not in contact with, and detached from the outer surface (13'') of said first end coil (13) and partially delimits said fume collection chamber (16); and wherein said annular sealing portion (57) of said closing flange (50) is at least partially arranged radially outside said annular contact portion (56), in a radial direction, orthogonal to the helix axis (L-L).