Variable Cross-Section Intake Duct for Premix Gas Burner Mixture Control
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Solution Overview
Problem
Existing premix gas burner systems face challenges in regulating fuel flow rates to maintain optimal fuel-oxidizer ratios, achieving high working pressures for low thermal flows, and preventing exhaust fumes from one burner from entering the intake duct of another, which can cause malfunction and comfort issues.
Innovation Solution
A device and method for controlling the fuel-oxidizer mixture in premix gas burners, featuring an intake duct with a mixing zone, an injection duct for fuel supply, a monitoring device for combustion state, a gas regulating valve, and a control unit that adjusts the fan speed and intake duct cross section to optimize mixture control independently of intake duct geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a fixed geometry intake duct with Venturi tube is used, then pressure losses are proportional to the square of the oxidizer flow rate, but high working pressures cannot be achieved for low thermal flows and energy dissipation cannot be limited for high thermal flows
Solution Approach 1:
The intake duct geometry is made variable through a regulator that adjusts the cross-sectional area according to the thermal flow rate. This dynamic adaptation allows the system to maintain optimal working pressures across different operating conditions, resolving the contradiction between achieving high pressures at low flows and limiting energy dissipation at high flows.
Solution Approach 2:
The system changes the geometric parameters of the intake duct (cross-sectional area) based on the thermal flow rate. By varying this parameter dynamically, the system optimizes pressure characteristics for different operating conditions, enabling high working pressures at low thermal flows while preventing excessive energy dissipation at high thermal flows.
2Reliability
If dedicated non return valves are mounted downstream of the combustion chamber, then exhaust fume recirculation is prevented, but the number of parts increases and production costs increase
Solution Approach 1:
The regulator is designed to perform multiple functions simultaneously: it adjusts the intake duct cross-section for optimal pressure control and also acts as a non-return valve to prevent exhaust fume recirculation. By merging these two separate functions into a single component, the system prevents exhaust fume recirculation without increasing the number of parts, thus resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The regulator is designed as a multi-functional component that serves both as a flow control device and as a non-return valve. This universal design eliminates the need for separate dedicated non-return valves, reducing part count while maintaining the reliability function of preventing exhaust fume recirculation.
3Manufacturing precision
If the intake duct geometry is fixed, then manufacturing is simpler, but precise regulation of fuel flow rates cannot be achieved independently of intake duct geometry
Solution Approach 1:
The system separates the regulation function from the intake duct geometry by introducing a独立的 regulator component. This segmentation allows the fuel flow rate regulation to be controlled independently of the fixed intake duct geometry, achieving precise regulation without complicating the manufacturing of the intake duct itself.
Solution Approach 2:
The regulator acts as an intermediary component between the fixed intake duct and the fuel injection system. It mediates the relationship between geometry and flow regulation, enabling precise fuel flow rate control without requiring complex intake duct geometry, thus resolving the contradiction between manufacturing precision and ease of manufacture.
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 solution allows for precise regulation of fuel flow rates, achieving high working pressures for low thermal flows and preventing exhaust fume recirculation, thereby enhancing combustion efficiency, reducing energy consumption, and improving system reliability and comfort.
Implementation Method 1
a fan which rotates at a speed of rotation... The fan is located in the intake duct to generate therein a flow of oxidizer in a direction of inflow oriented from the inlet to the delivery outlet
Implementation Method 2
The regulator is coupled to the intake duct to vary its cross section as a function of the speed of rotation of the fan... the first shutter is movable... to vary the first working cross section
Data Source
Figure 1~1A
Figure 2A~2B
Figure 3A~3B
AI summary
A device (1) for controlling a fuel-oxidizer mixture for a premix gas burner (100), comprises: an intake duct (2) for admitting the mixture into the burner (100); an injection duct (3), connected to the intake duct (2) to supply the fuel; a monitoring device (4) for checking the state of combustion in the burner (100); a gas regulating valve (7); a fan (9) located in the intake duct (2); a control unit (5) for controlling the speed of rotation of the fan (9) between a first and a second rotation speed, corresponding to a minimum flow rate of oxidizer (Qmin) and a maximum flow rate of oxidizer (Qmax), respectively; a regulator (8) coupled to the intake duct (2) and having a first aperture (811), adjustable through a first shutter (821), and a second aperture (812), adjustable through a second shutter (822). The control unit (5) is configured to drive the gas regulating valve (7) in real time.