Single-Pass Condensing Water Heater Heat Exchanger Layout
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fuel-fired water heaters have thermal efficiencies limited to 85-90% due to their non-condensing heat exchanger design, and there is a need for a single-pass heat exchanger with a heat transfer efficiency of at least 95%.
Innovation Solution
A fuel-fired water heater with a specially designed single-pass condensing type heat exchanger, featuring a primary non-condensing section and a secondary condensing section, where the primary section has a higher heat transfer rate and is made from conventional metal, while the secondary section is acid-resistant and made from porcelainized metal, facilitating efficient heat transfer and condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional non-condensing heat exchanger is used, then the device complexity is reduced, but the thermal efficiency is limited to 80-85%
Solution Approach 1:
The heat exchanger is divided into a primary non-condensing section and a secondary condensing section, allowing the system to achieve high thermal efficiency through condensation while maintaining structural manageability through clear functional segmentation
Solution Approach 2:
Different sections of the heat exchanger are designed with different properties: the primary section uses conventional metal for high heat transfer rate, while the secondary section uses acid-resistant porcelainized metal for condensation, optimizing each zone for its specific function
2Use of energy by moving object
If a single-pass condensing heat exchanger is used, then the thermal efficiency increases to 85-90%, but the material cost and corrosion resistance requirements increase
Solution Approach 1:
The heat exchanger applies different material properties to different sections: the primary non-condensing section uses conventional metal for cost-effectiveness, while only the secondary condensing section uses acid-resistant porcelainized metal where corrosion protection is necessary, optimizing both performance and manufacturing cost
Solution Approach 2:
By segmenting the heat exchanger into distinct non-condensing and condensing sections, the patent applies corrosion-resistant materials only where needed, reducing overall material cost while achieving high thermal efficiency through condensation
3Use of energy by moving object
If the primary section has higher heat transfer rate, then the overall heat transfer efficiency increases, but the heat transfer rate per height of secondary section must be optimized
Solution Approach 1:
The primary section is designed with higher heat transfer rate per height to maximize heat extraction in the non-condensing zone, while the secondary section is optimized for condensation heat transfer, with each section's properties tailored to its specific function
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 achieves a thermal efficiency of 95% or higher by optimizing heat transfer through sequential gas flow and condensation, reducing material costs and corrosion concerns.
Implementation Method 1
a single pass condensing type heat exchanger disposed within the interior of the tank... The heat exchanger has (1) a primary, non-condensing section defined by a combustion chamber... and (2) a secondary, condensing section defined by a plenum connected to lower ends of the primary flue tubes
Implementation Method 2
a combustion system operative to flow combustion gases sequentially through the combustion chamber, the first flue tubes, the plenum, and the second flue tube
Implementation Method 3
a secondary, condensing section defined by a plenum connected to lower ends of the primary flue tubes, and a secondary flue tube coupled to the plenum, coiling downwardly away from the plenum through a lower interior portion of the tank... in which flue gases condense within the heat exchanger
Data Source
AI summary
A fuel-fired water heater has a single pass condensing-type heat exchanger disposed within its water storage tank portion. The heat exchanger includes a primary non-condensing portion defined by a combustion chamber positioned in an upper interior portion of the tank and having a spaced series of vertical tubes depending therefrom. A secondary condensing portion of the heat exchanger is defined by a plenum having a top side connected to the bottom ends of the vertical tubes, and a bottom side from which a downwardly coiled flue tube depends. A fuel burner generates hot combustion gases that are sequentially flowed into the combustion chamber and then downwardly through the balance of the heat exchanger in a single pass.