Flame Temperature Sensor Drift Compensation for Hydrogen Heaters
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Solution Overview
Problem
Hydrogen-fired heating appliances face challenges in robustly controlling the combustion air ratio due to the lack of free charge carriers in the flame, leading to inaccurate ionization current measurements, and existing temperature sensor methods suffer from sensor drift, resulting in incomplete combustion and reduced efficiency.
Innovation Solution
A method using a resistance-based flame temperature sensor to determine and compensate for sensor drift, allowing precise control of the combustion air ratio by measuring the electrical resistance of the sensor when the burner is off, and applying a scaling factor to correct deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ionization current measurement is used to control combustion air ratio, then control is possible in gas-fired heaters, but measurement becomes unreliable in hydrogen-fired heaters due to insufficient free charge carriers
Solution Approach 1:
The patent replaces the ionization current measurement method (electrical measurement) with a flame temperature measurement method (thermal measurement). By using a flame temperature sensor to detect the temperature of the flame instead of measuring ionization current, the system achieves reliable combustion air ratio control in hydrogen-fired heaters where ionization current measurement fails due to insufficient free charge carriers.
2Reliability
If UV radiation detection is used to monitor hydrogen flame, then combustion air ratio control becomes possible, but costs increase and contamination susceptibility occurs
Solution Approach 1:
The patent replaces UV radiation detection (optical measurement) with flame temperature measurement (thermal measurement). By using a temperature sensor to detect flame temperature and infer combustion air ratio from that data, the system achieves reliable hydrogen flame monitoring without the high costs and contamination issues associated with UV detection equipment.
Solution Approach 2:
The patent uses flame temperature as an intermediary parameter to indirectly determine combustion air ratio. Instead of directly measuring combustion air ratio or using complex UV detection, the system measures flame temperature (which varies with combustion air ratio) and uses this intermediate measurement to control the combustion process, simplifying the monitoring system.
3Temperature
If temperature sensor is used for combustion control, then flame temperature information becomes available, but sensor drift occurs due to aging and oxidation
Solution Approach 1:
The patent implements a feedback mechanism where the measured flame temperature is continuously used to adjust the combustion air ratio. The control system monitors the flame temperature signal and dynamically adjusts the air-to-fuel mixture to maintain optimal combustion conditions, compensating for any sensor drift through continuous adaptive control.
Solution Approach 2:
The patent performs preliminary calibration by establishing the relationship between flame temperature and combustion air ratio before operation. By pre-determining the target flame temperature corresponding to the desired combustion air ratio, the system can use this predetermined information to guide real-time control adjustments, improving response accuracy.
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
Ensures consistently precise control of the combustion air ratio, compensating for sensor drift and maintaining efficient operation of hydrogen-fired heating devices without structural modifications.
Implementation Method 1
measuring the electrical resistance of the flame temperature sensor when the burner of the heater is switched off
Implementation Method 2
a resistance-based flame temperature sensor
Implementation Method 3
determining a scaling of the electrical resistance of the flame temperature sensor that compensates for the deviation determined in step c)
Data Source
Figure 1a~1c
Figure 2
Figure 3~5
AI summary
A method is proposed for operating a heating appliance (1) with a burner (3) to which a mixture of combustion air and fuel gas is supplied, and with control of the combustion air ratio of the mixture based on a signal from a resistance-based flame temperature sensor (6), comprising at least the following steps: a) determining the electrical resistance of the flame temperature sensor (6) with the burner (3) of the heating appliance (1) switched off, b) determining a deviation (16) from a resistance of the flame temperature sensor (6) assumed for the control of the combustion air ratio, c) determining a scaling of the resistance of the flame temperature sensor (6) that compensates for the deviation (16) determined in step c), and d) operating the heating appliance (1) with the electrical resistance of the flame temperature sensor (6) scaled in this way.Advantageously, the proposed method can compensate for sensor drift of a flame temperature sensor (6) and thus enable long-term stable operation of the heating device (1).