Premix Gas Burner Modulation Range Venturi Segmentation
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Solution Overview
Problem
Premix burners face limitations in modulation range and head losses, particularly at maximum thermal power, which restrict their ability to efficiently provide varying heat outputs needed for modern heating and sanitary water production, and are costly due to high-performance fan and gas valve requirements.
Innovation Solution
A premix burner design featuring multiple Venturi tubes with baffle elements and open/close mechanisms that adjust to maintain pressure differences and fluid-dynamic resistance, allowing for increased modulation ratios and reduced head losses by optimizing air/gas mixing and gas valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single Venturi tube is used for air/gas mixing, then the device structure is simple, but the modulation range is limited to 1:5 and head losses are high at maximum thermal power
Solution Approach 1:
The single Venturi tube is divided into multiple parallel Venturi tubes (first, second, and third Venturi tubes with different minimum sections). This segmentation allows each tube to handle different flow ranges, collectively achieving a broader modulation range of 1:18 while maintaining structural simplicity through parallel configuration
Solution Approach 2:
Each Venturi tube is designed with different minimum sections tailored to specific operating conditions. The first Venturi tube has a larger minimum section for high flow conditions, while the second and third have progressively smaller sections for lower flow conditions, optimizing local fluid-dynamic characteristics for different thermal power levels
2Reliability
If high-performance fans and gas valves are used to maintain pressure differences, then combustion efficiency is improved, but production costs increase
Solution Approach 1:
The system uses the natural fluid-dynamic resistance of the multiple parallel Venturi tubes to automatically generate and maintain the required pressure differences. The different minimum sections create inherent resistance variations that self-regulate the air/gas mixing ratio based on flow conditions, eliminating the need for expensive high-performance fans and gas valves
Solution Approach 2:
The invention changes the geometric parameters of the Venturi tubes, specifically the minimum sections, to create different fluid-dynamic resistances. This parameter variation allows the system to maintain effective pressure differences across a wide modulation range using standard, cost-effective fan and gas valve components
3Adaptability or versatility
If the minimum section of the Venturi tube is reduced to increase modulation range, then low thermal power operation is improved, but head losses increase at maximum thermal power
Solution Approach 1:
Instead of using a single small minimum section, the system segments the flow path into multiple parallel Venturi tubes with progressively larger minimum sections. This allows the total effective area to be optimized for high flow conditions while maintaining sufficient resistance for low flow conditions, reducing head losses at maximum thermal power
Solution Approach 2:
The parallel configuration of Venturi tubes with different minimum sections creates a dynamic system where the effective flow path adjusts automatically with thermal power demand. At low thermal power, flow concentrates through tubes with smaller minimum sections; at maximum thermal power, flow distributes across all tubes including those with larger minimum sections, optimizing performance across the full modulation range
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 enhances modulation range from 1:5 to 1:18, reduces head losses, and allows for efficient operation at low thermal power values, improving combustion hygiene and energy efficiency while being less costly to produce.
Implementation Method 1
The mixer 11 comprises a device for localized pressure loss 11A, in this case constituted by a Venturi tube
Implementation Method 2
The amount of gas released by the gas valve 14 to the mixer 11 is correlated to the pressure difference existing between a pressure P2 at output from the gas valve 14 (pressure P2 equal to the value of the pressure P1) and a pressure P3 existing in the narrowest point (localized-pressure-loss device 11A) of the Venturi-tube air/gas mixer 11
Data Source
AI summary
An air/gas premix burner, comprising:a fan for sending the air/gas mixture to a combustion head;a gas valve for regulating admission of the combustible gas;an air/gas mixer, which comprises a device for localized loss of pressure; anda combustion head.The premix burner is characterized in that the air/gas mixer comprises at least two channels for mixing the air with the gas; in addition, a channel is provided with an open/close element designed to regulate the flow rate of the mixture.