Heating Appliance Fuel Mixing Ratio Control via Partial Air Flow Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling the fuel gas to air mixing ratio in heaters are not independent of fuel gas type or ambient conditions, and struggle with reliable control at low burner outputs, requiring complex calibration and measurement of multiple variables.
Innovation Solution
A method that divides the air mass flow into two partial flows, with a smaller second partial flow mixed with the fuel gas mass flow to form a premix, allowing for real-time material property detection and adjustment of the mixing ratio via a sensor, enabling broader modulation range and improved control over varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air mass flow is not divided into partial flows, then the system structure is simpler, but the sensor cannot detect material properties accurately at low burner outputs and the modulation range is limited
Solution Approach 1:
The air mass flow is divided into a first partial air mass flow and a second partial air mass flow. The second partial air mass flow is mixed with the fuel gas mass flow to form a premix that is supplied to the sensor. This segmentation allows the sensor to detect material properties accurately by measuring the premix composition, enabling reliable control at low burner outputs while maintaining a relatively simple overall structure.
2Measurement precision
If all input variables (air volume flow, gas volume flow, fuel gas properties) are measured and monitored, then the control accuracy is improved, but the device complexity and measurement requirements increase significantly
Solution Approach 1:
Instead of measuring all input variables (air volume flow, gas volume flow, fuel gas properties) separately, the invention extracts only the essential information by measuring the material properties of the premix (fuel gas and second partial air mass flow) that is supplied to the sensor. This reduces the measurement system complexity while maintaining sufficient control accuracy, as the premix measurement reflects the actual mixing ratio regardless of individual variable variations.
Solution Approach 2:
The premix acts as an intermediary substance that combines the fuel gas and second partial air mass flow before reaching the sensor. By measuring the material properties of this intermediate premix, the system indirectly determines the mixing ratio without requiring direct measurement of all individual input variables, thereby simplifying the measurement system while maintaining control accuracy.
3Reliability
If the flame signal measurement is used for combustion regulation, then the control is possible, but the flame signal drops sharply at low outputs and reliable control is no longer possible
Solution Approach 1:
The invention replaces the flame signal measurement method (which relies on optical detection of flame characteristics) with a sensor-based measurement of material properties (such as thermal conductivity or heat capacity) of the premix. This substitution enables reliable control at low burner outputs where flame signals become weak or unstable, as the material property measurement remains accurate regardless of burner output level.
4Ease of operation
If the mixing ratio is controlled based on ionization characteristics, then the control method is established, but calibration of the ionization characteristic and adjustment of burner geometry are required
Solution Approach 1:
The invention changes the control parameter from ionization characteristics (which require calibration and geometry adjustment) to material properties of the premix (such as thermal conductivity or heat capacity). This parameter change eliminates the need for calibration of ionization characteristics and adjustment of burner geometry, making the control operation simpler and more universally applicable to different fuel types and installation conditions.
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 approach allows for precise regulation of the fuel gas to air mixing ratio across a wide range of burner outputs, independent of fuel gas type and ambient conditions, ensuring reliable combustion and efficient heat production.
Implementation Method 1
the material properties of the premix formed from the second partial air mass flow and gas mass flow are detected by a sensor and a premix ratio of the premix is determined therefrom
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for controlling a mixing ratio of fuel gas and air for a heating appliance, wherein an air mass flow is first divided and mixed with the fuel gas mass flow only via a partial flow to form a premixture, wherein material properties of the premixture are detected via a sensor and the mixing ratio of fuel gas and air is calculated therefrom.