Sealed Combustion Chamber Airflow Layout for Stable Water Heater Ignition
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Solution Overview
Problem
Modern fuel-fired direct vent water heaters with sealed combustion chambers face issues such as diminished ignition performance, sooting, decreased burner flame stability, and increased NOx emissions.
Innovation Solution
A specially designed combustion chamber assembly with a hollow body, air intake plenum, and air transfer passages that funnel combustion air to the burner, ensuring precise air delivery and distribution, enhancing ignition and combustion performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a sealed combustion chamber design is used, then flammable vapor ignition resistance is improved, but ignition performance deteriorates
Solution Approach 1:
The sealed combustion chamber is segmented into distinct zones: a primary combustion zone with a burner assembly, a secondary combustion zone with additional burners, and an air intake plenum. This segmentation allows different regions to serve different functions - the primary zone ensures reliable ignition while the sealed structure maintains vapor resistance, and the secondary zone enhances combustion completeness to reduce emissions.
Solution Approach 2:
An air transfer passage acts as an intermediary element connecting the air intake plenum to the primary combustion zone. This intermediary structure controls and optimizes the flow of combustion air, ensuring sufficient oxygen supply for reliable ignition while maintaining the sealed configuration that provides flammable vapor ignition resistance.
2Object-affected harmful factors
If a sealed combustion chamber design is used, then flammable vapor ignition resistance is improved, but combustion performance deteriorates
Solution Approach 1:
The combustion system is divided into primary and secondary combustion zones with separate burner assemblies. The primary zone handles initial combustion while the secondary zone ensures complete combustion of remaining fuel and gases, thereby maintaining high combustion performance within the sealed chamber that provides vapor ignition resistance.
Solution Approach 2:
The patent introduces a vertical dimension to combustion air flow by incorporating an air intake plenum beneath the combustion chamber and using upwardly extending air transfer passages. This three-dimensional air distribution system ensures optimal oxygen supply throughout the combustion zones, enhancing combustion performance while preserving the sealed configuration.
3Object-affected harmful factors
If a sealed combustion chamber design is used, then flammable vapor ignition resistance is improved, but NOx emissions increase
Solution Approach 1:
The combustion process is segmented into primary and secondary zones. The secondary combustion zone is specifically designed to complete the combustion of fuel and gases that escape the primary zone, ensuring more complete combustion and reducing the formation of NOx emissions while maintaining the sealed vapor-resistant chamber.
Solution Approach 2:
The patent ensures continuous combustion action through the dual-zone burner system. The secondary burners continuously combust remaining fuel and combustion products, preventing incomplete combustion that would lead to NOx formation. This continuous combustion process occurs within the sealed chamber that maintains vapor ignition resistance.
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 solution improves ignition performance, reduces NOx emissions, and increases combustion efficiency by accurately controlling combustion air delivery to the burner, addressing the operational challenges of sealed combustion chambers.
Implementation Method 1
a first passage for receiving air drawn inwardly through the combustion air intake opening and flowing a portion of the received air to the air transfer opening for transfer therethrough into the combustion chamber
Data Source
AI summary
A fuel-fired water heater is provided with a combustion chamber assembly, representatively a sealed combustion chamber assembly, operative to create from combustion air delivered thereto via a circumferentially limited vertical side portion thereof a flow of primary combustion air to the underside of a centrally disposed fuel burner within the assembly via a first location underlying the burner, a first flow of secondary combustion air delivered to the burner via the first location, and a second flow of secondary combustion air delivered to the burner via a second location outwardly circumscribing the first location.