Premixer Baffle Design for Backflow Prevention in Gas Water Heaters
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Solution Overview
Problem
Fully premixed combustion gas water heaters are prone to failure due to anti-backflow devices freezing in cold conditions, leading to damage from cold air and high-temperature flue gas backflow, which compromises product safety and functionality.
Innovation Solution
An anti-backflow premixer with a baffle mechanism that seals the premixing chamber when not in use, utilizing gravity or a resilient element to block air flow, and opens under fan pressure for stable air-fuel mixing, preventing backflow and maintaining a stable air-fuel ratio during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-backflow device is provided at the smoke exhaust port, then backflow of cold air and flue gas is prevented, but the device freezes in cold conditions and cannot open
Solution Approach 1:
The invention extracts the anti-backflow function from a separate mechanical device and integrates it into the premixer structure itself. The baffle is positioned within the premixing chamber to block the air outlet passage, eliminating the need for a separate anti-backflow device at the smoke exhaust port that would be susceptible to freezing.
Solution Approach 2:
The baffle is preliminarily positioned to block the air outlet passage before operation begins. This preliminary blocking action prevents backflow without requiring any active operation or mechanical movement during cold conditions, thus avoiding the freezing problem that affects operable anti-backflow devices.
2Reliability
If the baffle blocks the air outlet passage completely, then backflow is prevented, but air-fuel mixing is insufficient during operation
Solution Approach 1:
The baffle is designed to be movable rather than fixed, allowing it to transition between a blocking position (for backflow prevention) and an open position (for air-fuel mixing). The fan-generated negative pressure dynamically opens the baffle during operation, while gravity causes it to return to the blocking position when the fan stops, thus resolving the contradiction between complete blocking and sufficient mixing.
Solution Approach 2:
The baffle undergoes periodic movement between blocked and open states corresponding to the on/off cycles of the fan. During operation, the baffle opens to allow air-fuel mixing; when the fan stops, the baffle returns to the blocked position to prevent backflow, creating a rhythmic alternation that satisfies both requirements at different times.
3Reliability
If a resilient element is used to restore the baffle, then the baffle returns to the blocked position reliably, but the device complexity increases
Solution Approach 1:
The baffle utilizes its own weight (gravity) to automatically restore itself to the blocked position after the fan stops operating. This self-service mechanism eliminates the need for additional resilient elements or restoration devices, maintaining structural simplicity while ensuring reliable return to the backflow prevention position.
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
Prevents backflow of cold air and high-temperature flue gas, ensuring safe and stable combustion, extending product life, and improving safety and thermal load adjustment range.
Implementation Method 1
The baffle blocks the air outlet passage using its own gravity
Implementation Method 2
a negative pressure generated by the fan overcomes the gravity of the baffle to open the baffle
Data Source
AI summary
Disclosed are an anti-backflow premixing device and a fuel gas water heater, where the anti- backflow premixing device includes a casing body, a premixing cavity is provided in the casing body, and the premixing cavity includes a gas outlet pathway; a baffle, the baffle is connected in the casing body, the baffle has a first position and a second position, the baffle can continuously move between the first position and the second position, the baffle obstructs the gas outlet pathway of the premixing cavity when at the first position, and the gas outlet pathway gradually opens when the baffle is moved from the first position to the second position; and a fuel gas passage, the fuel gas passage and the premixing cavity being in communication.