Perforated Diffuser Plate for Premixed Burner Temperature Uniformity
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Solution Overview
Problem
Fuel-fired heating appliances experience undesirable uneven heating of combustion product-receiving heat exchanger tubes due to non-uniform temperature distribution, leading to inefficient heating.
Innovation Solution
A perforated diffuser plate is installed between the fuel/air mixture supply housing and the burner box, with a specific perforation pattern that increases fuel/air mixture flow through end heat exchanger tubes and decreases flow through central tubes, alleviating temperature distribution issues and improving fuel/air mixing, thereby reducing NOx levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel/air mixture is burned in a conventional burner box, then combustion occurs to heat air, but non-uniform temperature distribution occurs in heat exchanger tubes causing uneven heating
Solution Approach 1:
The diffuser plate introduces non-uniform velocity distribution of fuel/air mixture at the burner box inlet, creating locally optimized combustion conditions. The varying velocity profile ensures that different regions of the heat exchanger tubes receive appropriate fuel/air mixture flow rates, resulting in uniform temperature distribution across all tubes while maintaining overall heating efficiency.
2Temperature
If fuel/air mixture flows through the burner box, then combustion generates hot gases, but undesirable non-uniform temperature distribution is present in the heat exchanger tube array
Solution Approach 1:
The diffuser plate modifies the velocity parameter of the fuel/air mixture at the burner box inlet. By creating a specific non-uniform velocity distribution pattern, the system achieves uniform combustion heat release across the heat exchanger tube array. This parameter change ensures stable combustion while eliminating temperature non-uniformity, as the velocity distribution is designed to compensate for geometric variations in the tube array.
3Ease of manufacture
If conventional burner design is used, then simple structure is maintained, but uneven heating of heat exchanger tubes occurs
Solution Approach 1:
The diffuser plate serves as an intermediary component installed at the inlet of the burner box. This simple plate structure with varying thickness or perforation patterns modifies the fuel/air mixture flow to achieve uniform temperature distribution across heat exchanger tubes. The diffuser plate adds minimal structural complexity while effectively resolving the temperature uniformity issue through its flow distribution 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 diffuser plate achieves a more uniform temperature distribution across the heat exchanger tube array, enhances fuel/air mixing, and reduces NOx emissions, providing a cost-effective solution to the heating inefficiencies.
Implementation Method 1
A diffuser plate is installed between the fuel/air mixture supply housing and the burner box with a specific perforation pattern that increases fuel/air mixture flow through end heat exchanger tubes and decreases flow through central tubes
Implementation Method 2
a suitable ignition device is disposed to combust the fuel air mixture and thereby create hot combustion gases used to heat air for delivery to a conditioned space
Implementation Method 3
The hot combustion gases are flowed through a series of heat exchanger tubes, externally across which the air to be heated is flowed
Data Source
AI summary
To substantially reduce inequality in hot combustion flow rates through first and second heat exchanger tubes from a fuel-fired heating appliance burner box connected thereto and internally combusting a fuel/air mixture received therein from a source thereof to create the hot combustion gas, a perforated diffuser member having a non-uniform perforation pattern is provided. The fuel/air mixture is flowed through the perforated diffuser member into the interior of the burner box. The non-uniform perforation pattern of the diffuser member functions to alter relative combustion gas flow rates through the first and second heat exchanger tubes in a manner reducing an undesirable operating temperature differential therebetween.