Fuel Heater Combustion Chamber with Exhaust Gas Recirculation
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Solution Overview
Problem
Fuel-operated vehicle heaters emit high levels of pollutants, particularly NOx, due to inefficient combustion processes.
Innovation Solution
A combustion chamber assembly with an exhaust gas recirculation system that uses a Venturi nozzle effect and a catalytic converter to reduce pollutant emissions by recirculating combustion gases and converting CO and HC into CO2 and H2O, while preheating combustion air and transferring heat to a heat transfer medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional combustion process is used in fuel-operated vehicle heaters, then heating efficiency is maintained, but pollutant emissions (particularly NOx) are high
Solution Approach 1:
The patent implements an exhaust gas recirculation system where combustion gases are extracted from the exhaust stream and fed back into the combustion chamber through recirculation channels. This feedback mechanism reduces the oxygen concentration and temperature in the combustion zone, thereby significantly reducing NOx formation while maintaining stable combustion and heating efficiency.
Solution Approach 2:
The patent changes the chemical and thermal parameters of the combustion process by introducing recirculated exhaust gases. This alters the oxygen concentration, temperature distribution, and residence time in the combustion chamber, transforming the combustion conditions to reduce pollutant formation while preserving heating performance.
2Object-generated harmful factors
If exhaust gas recirculation is implemented to reduce NOx emissions, then pollutant output decreases, but combustion stability may be compromised
Solution Approach 1:
The patent applies local quality by creating different gas composition zones within the combustion chamber. Recirculated exhaust gases are introduced at specific locations through controlled channels, creating localized regions with reduced oxygen concentration where NOx formation is suppressed, while other zones maintain conditions favorable for stable combustion.
Solution Approach 2:
The recirculated exhaust gases act as an intermediary substance that mediates between the fuel combustion process and the exhaust emission. By introducing these intermediate gases with controlled composition and temperature, the system reduces NOx formation while the overall combustion process remains stable through proper design of the recirculation system.
3Object-generated harmful factors
If a catalytic converter is integrated into the combustion chamber assembly, then CO and HC emissions are reduced, but device complexity increases
Solution Approach 1:
The patent merges the catalytic converter with the combustion chamber assembly by integrating it into the exhaust gas recirculation system. The catalyst is positioned within the recirculation channels or at the exhaust outlet, combining the emission treatment function with the existing combustion and recirculation structure, thereby reducing overall system complexity compared to separate catalytic aftertreatment systems.
Solution Approach 2:
The integrated catalytic converter serves multiple functions: it reduces CO and HC emissions through catalytic oxidation, preheats the recirculated exhaust gases using exhaust heat, and potentially contributes to NOx reduction through selective catalytic reduction. This multi-functionality reduces the need for separate components, simplifying the overall system.
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
Significantly reduces NOx emissions and overall pollutant output by reintroducing combustion gases into the combustion process and utilizing a catalytic converter to purify exhaust gases, while efficiently utilizing heat generated in the process.
Implementation Method 1
the flame baffle together with the flame tube and/or the circumferential wall defines an exhaust gas transfer chamber, and that the exhaust gas recirculation opening arrangement comprises at least one first exhaust gas recirculation opening connecting the exhaust gas recirculation chamber with the exhaust gas transfer chamber and at least one second exhaust gas recirculation opening connecting the exhaust gas transfer chamber with the combustion chamber and/or the exhaust gas flow chamber
Implementation Method 2
a catalyst arrangement through which combustion gases flowing in the exhaust gas recirculation chamber are provided. This catalyst arrangement can be particularly effective in reducing the CO and HC content in the combustion gases
Implementation Method 3
the bottom region comprises an evaporator medium carrier and porous evaporator medium on a side of the evaporator medium carrier facing the combustion chamber
Implementation Method 4
the bottom region comprises an evaporator medium carrier and porous evaporator medium on a side of the evaporator medium carrier facing the combustion chamber
Implementation Method 5
The combustion gases transfer heat to a heat transfer medium flowing around the housing on its side facing away from the flame tube
Implementation Method 6
The combustion gases transfer heat to a heat transfer medium flowing around the housing on its side facing away from the flame tube
Data Source
Figure 1
Figure 2
AI summary
A combustion chamber assembly for a fuel-operated vehicle heater, comprising a combustion chamber housing (12) with a combustion chamber (18) bounded by a circumferential wall (14) and a bottom region (16), a flame tube (30) extending along the circumferential wall (14) in the direction of a longitudinal axis (L) of the housing and surrounding an exhaust gas flow space (32) open in the direction of the longitudinal axis (L), and a flame baffle (34) with a flow opening (60), wherein an exhaust gas recirculation space (46) is formed between the flame tube (30) and a housing (38) surrounding it, is characterized in that in a first axial end region (48) of the exhaust gas recirculation space (46) the exhaust gas flow space (32) is open to the exhaust gas recirculation space (46) and in the exhaust gas recirculation space (46) a flue gas opening (60) through which combustion gases flowing in the exhaust gas recirculation space (46) are provided. Catalyst arrangement (54) provided.