Control method for hydrogen-fueled domestic gas water heater
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Solution Overview
Problem
Existing domestic gas water heaters struggle with stable combustion and safety issues when using hydrogen as fuel, due to differences in physical and chemical properties compared to natural gas and liquefied petroleum gas, leading to potential safety hazards, reduced heat load, and corrosion from condensate water.
Innovation Solution
A control method for a hydrogen-fueled domestic gas water heater that includes a combustor with three combustion groups, a gas mixing system with electromagnetic valves, and a controller that adjusts hydrogen flow and air flow to maintain optimal combustion ratios, preventing flame flashback and corrosion, while allowing for a wide heat load adjusting range and constant hot water output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydrogen is used as fuel in existing gas water heaters, then clean and low-carbon energy benefits are achieved, but stable combustion cannot be maintained due to different physical and chemical properties
Solution Approach 1:
The patent adjusts combustion parameters including air-to-fuel ratio, combustion chamber pressure, and ignition timing to accommodate hydrogen's different combustion characteristics compared to natural gas, thereby achieving stable combustion while maintaining clean energy benefits
Solution Approach 2:
The patent introduces a mixed gas system that combines hydrogen with other gases to create an intermediate combustion mixture, which provides the benefits of hydrogen combustion while mitigating its instability issues in existing equipment
2Measurement precision
If flame induction needle is used to monitor combustion, then flameout detection is achieved for natural gas and liquefied petroleum gas, but detection fails for hydrogen due to inability to generate plasma
Solution Approach 1:
The patent replaces the flame induction needle (electrical/plasma-based detection) with alternative detection methods such as optical sensors or thermal sensors that can detect hydrogen combustion without relying on plasma generation, thereby achieving both accurate flameout detection and compatibility with hydrogen fuel
Solution Approach 2:
The patent introduces an intermediary detection mechanism that indirectly monitors hydrogen combustion through measurable parameters such as temperature changes or gas flow characteristics, bypassing the need for direct plasma-based detection
3Power
If hydrogen flow rate is increased to compensate for low density and heat productivity, then heat load is maintained, but flame flashback tendency worsens and fan noise increases
Solution Approach 1:
The patent optimizes the air-to-fuel ratio and combustion chamber pressure parameters to enable stable combustion at lower hydrogen flow rates, thereby maintaining required heat load while reducing flame flashback risk and associated fan noise
Solution Approach 2:
The patent divides the combustion process into staged combustion zones, allowing controlled oxidation that maintains heat output while preventing premature flashback by managing combustion progression through distinct stages
4Power
If gaseous water from hydrogen combustion passes through exhaust pipe, then combustion completeness is achieved, but condensate water corrodes exhaust pipe and heat exchangers
Solution Approach 1:
The patent utilizes the condensate water from hydrogen combustion as a heat transfer medium in the heat exchanger, converting the harmful corrosive condensate into a useful cooling fluid that improves thermal efficiency while reducing corrosion through controlled condensation processes
Solution Approach 2:
The patent introduces corrosion-resistant coating materials as an intermediary protective layer between the condensate water and the metal surfaces of the exhaust pipe and heat exchangers, allowing the system to handle hydrogen combustion products without suffering corrosion damage
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 method ensures stable and safe hydrogen combustion, prevents flame flashback, and maintains a wide heat load adjusting range, allowing for constant temperature hot water output while reducing corrosion and improving heat efficiency.
Implementation Method 1
an oxygen sensor is installed on an exhaust pipe communicating with a condensation chamber; and the oxygen sensor is connected with the controller through a control line, and the controller reads oxygen concentration signal output by the oxygen sensor
Implementation Method 2
an air outlet of a fan communicates with an inlet of the gas mixing pipe
Implementation Method 3
an outlet of a left gas mixing pipe branch provided with a first electromagnetic valve communicates with the left combustion group, an outlet of a middle gas mixing pipe branch communicates with the middle combustion group, an outlet of a right gas mixing pipe branch provided with a second electromagnetic valve communicates with the right combustion group
Implementation Method 4
a combustor containing three combustion groups is installed in a combustion chamber
Implementation Method 5
an oxygen sensor is installed on an exhaust pipe communicating with a condensation chamber
Data Source
AI summary
Disclosed is a control method for a hydrogen-fueled domestic gas water heater. A staged combustion technology and a fully premixed combustion technology are combined in the method, a controller judges a combustion mode according to inlet water flow and set hot water input temperature, staged combustion of the hydrogen on a combustor is achieved due to the arrangement of two electromagnetic valves and the staged combustor, and meanwhile the stable combustion of the hydrogen can be achieved by adjusting a rotating speed of a fan and magnitude of currents of a gas proportional valve; and an oxygen sensor is arranged on a exhaust pipe, and the controller judges whether actual hydrogen combustion reaches an optimal state by monitoring outlet water temperature and oxygen concentration in flue gas and performs adjustment.