Heat Exchanger Header Drainage for Small-Diameter Pipes
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Solution Overview
Problem
The reduction in diameter of heat absorbing pipes in heat exchangers leads to water film formation at pipe end openings due to water surface tension, causing water to remain in the pipes, which impedes downsizing and increases the number of components and assembly processes.
Innovation Solution
A heat exchanger design with heat absorbing pipes arranged in a multi-tier configuration, where both pipe ends are connected to two headers on a side plate, and a drainage plate is disposed in the lower header to form a drainage passage that prevents water film formation by directing water smoothly to a connecting port, allowing for reliable water removal without extending components outside the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diameter of heat absorbing pipes is reduced to increase heat transfer area and enable downsizing, then thermal efficiency is improved and more pipes can be provided in limited space, but water film formation occurs at pipe end openings due to water surface tension, causing water to remain in the pipes
Solution Approach 1:
The invention extracts the drainage function from the heat absorbing pipe system by providing a separate drainage passage through the header. This allows water removal to be handled independently from the heat transfer function, enabling the use of smaller diameter pipes without water film formation issues.
Solution Approach 2:
The header acts as an intermediary component that provides a drainage passage between the heat absorbing pipes and the external drainage system. This mediator allows water to be removed from the pipes without interfering with the heat transfer process inside the pipes.
2Reliability
If extended tubular bodies or headers are provided outside the casing to drain water from heat absorbing pipes, then water removal is achieved, but downsizing of the heat exchanger is impeded
Solution Approach 1:
The invention merges the drainage function with the existing header structure that is already part of the heat exchanger assembly. By integrating the drainage passage into the header rather than adding separate external drainage components, the overall size of the heat exchanger is not increased.
Solution Approach 2:
The header is designed to serve multiple functions: it connects the heat absorbing pipes to the water supply system and simultaneously provides a drainage passage for water removal. This multi-functionality eliminates the need for separate drainage components.
3Reliability
If extended tubular bodies are provided for each heat absorbing pipe to enable water drainage, then water removal is reliable, but the number of components and brazing portions increases, resulting in more assembling processes
Solution Approach 1:
The invention combines the drainage function for multiple heat absorbing pipes into a single header structure with a common drainage passage. This eliminates the need for individual extended tubular bodies for each pipe, significantly reducing the number of components and brazing portions.
Solution Approach 2:
The header serves as a universal drainage component that handles water removal from multiple heat absorbing pipes simultaneously through a single integrated drainage passage, rather than requiring pipe-specific drainage components.
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 configuration enables reliable water removal from heat absorbing pipes even with reduced diameters, preventing freezing and allowing for downsizing and high thermal efficiency without increasing the number of components or assembly processes.
Implementation Method 1
formation of the water film at a leading end opening of the extended tubular body 93 is prevented at drainage time by hydraulic head pressure in the extended tubular body 93
Implementation Method 2
water introduced from an external pipe to each of the heat absorbing pipes through the header is heat-exchanged and heated by combustion exhaust gas
Implementation Method 3
introducing water from external pipe to the heat absorbing pipes through the inflow header to condense moisture in the combustion exhaust gas
Implementation Method 4
a water film is formed at a pipe end opening of the heat absorbing pipe due to water surface tension, causing the water to remain at a downstream portion of the heat absorbing pipe
Data Source
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AI summary
Provided are a heat exchanger that does not impede downsizing and removes water in the heat absorbing pipe adequately with a simple configuration even when the reduction in diameter of the heat absorbing pipe is made. A heat exchanger 5 in which heat absorbing pipes 51 are disposed in a multi-tier arrangement within a casing 50 which is the passage of combustion exhaust gas, both pipe ends 511, 512 of each of the heat absorbing pipes 51 are connected respectively to two headers 54, 55 provided on a side plate 52 of the casing 50, and water introduced from an external pipe 63 to each of the heat absorbing pipes 51 through the header 54 is heat-exchanged and heated by combustion exhaust gas. The pipe ends 511, 512 of the heat absorbing pipes 51 are arranged at a predetermined vertical interval. A drainage plate 56 for forming a drainage passage through which the water that has reached the pipe end openings 51A of respective heat absorbing pipes 51 is removed during drainage operation for the heat absorbing pipes 51, is disposed in the header 54 disposed on a lower side of the heat absorbing pipes 51 so as to face a number of the pipe end openings 51A vertically arranged in a state of continuous.