Flow-Directing Insert for Quiet Evaporator Burner Airflow
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Solution Overview
Problem
Heating devices with evaporator burners suffer from unpleasant operating noise due to combustion instability, which is often discovered late in development, leading to high costs and compromises in combustion process, emissions, and performance.
Innovation Solution
A flow-directing insert is designed for insertion into the heating device's evaporator burner, featuring a tongue-shaped first portion that overlays combustion air passage openings and a second portion fixed in the fan chamber, reducing pressure fluctuations and noise by maintaining airflow without throttling, allowing for modular design and late-stage optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the combustion air guiding element is interrupted for assembly reasons, then the fuel supply tube can be arranged, but combustion instability and noise increase
Solution Approach 1:
The flow-directing insert is divided into a first portion that overlays combustion air passage openings and a second portion fixed in the fan chamber, allowing modular assembly while maintaining combustion stability. This segmentation enables the fuel supply tube to be arranged without interrupting the combustion air guiding element, thus avoiding combustion instability and noise.
Solution Approach 2:
The flow-directing insert acts as an intermediary component between the combustion air passage openings and the fan chamber. It guides combustion air flow smoothly without requiring interruption of the combustion air guiding element, thereby preventing combustion instability and noise while facilitating assembly.
2Ease of operation
If combustion air passage openings are throttled to control flow, then airflow can be regulated, but pressure fluctuations and noise increase
Solution Approach 1:
Instead of throttling combustion air passage openings, the invention changes the flow direction parameters by using a flow-directing insert to guide combustion air smoothly from the fan chamber through the evaporator receptacle. This maintains stable pressure and reduces noise while still regulating airflow effectively.
Solution Approach 2:
The flow-directing insert serves as an intermediary that redirects combustion air flow without creating throttling effects. It provides a smooth flow path that regulates airflow while avoiding pressure fluctuations and noise associated with restricted openings.
3Object-generated harmful factors
If the burner geometry is changed to reduce noise, then noise spectrum can be optimized, but combustion process, emissions, and performance are affected
Solution Approach 1:
The noise reduction function is segmented into a separate flow-directing insert component rather than modifying the entire burner geometry. This allows optimization of the noise spectrum while preserving the original combustion chamber and evaporator receptacle designs that ensure stable combustion process and controlled emissions.
Solution Approach 2:
The flow-directing insert acts as an intermediary component that addresses noise spectrum issues without requiring changes to the core burner geometry. It modifies only the airflow path in the fan chamber and combustion air passage areas, leaving the combustion process, emissions, and performance characteristics unchanged.
4Temperature
If the evaporator receptacle base wall is cooled over the entire area, then premature fuel vaporization is prevented, but the combustion air pre-chamber cannot be properly formed
Solution Approach 1:
The base wall cooling is applied locally rather than uniformly across the entire area. The flow-directing insert allows combustion air to flow along the outer surface of the evaporator receptacle and cool specific regions of the base wall where needed, while leaving other areas available for proper combustion air pre-chamber formation.
Solution Approach 2:
The cooling function is extended to a different spatial dimension by having combustion air flow along the outer surface of the evaporator receptacle in a circumferential path. This provides effective cooling of the base wall through convection along the surface area without requiring direct contact or blocking of the combustion air pre-chamber formation area.
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 flow-directing insert effectively reduces noise spectrum fluctuations and allows for modular component matching, enabling cost-effective optimization of the heating device without affecting combustion performance or emissions.
Implementation Method 1
a flow-directing insert (28) which is configured for placement on an exterior surface of the evaporator receptacle (10), the flow-directing insert (28) comprising a first region (28a) which extends along the circumferential wall (30) and overlies a combustion air passage opening (22) and a second region (28b) which extends along the base wall (26)
Implementation Method 2
a second flow path 46 is provided within the heat exchanger 6 in which cooling fluid of the motor vehicle is guided. The first 42 and the second 46 flow paths are arranged in such a way that, in use, heat is effectively transferred from the exhaust gases to the cooling fluid.
Implementation Method 3
heat is effectively transferred from the exhaust gases to the cooling fluid
Implementation Method 4
an evaporator element 12 for evaporating liquid fuel
Implementation Method 5
a combustion chamber 8, an evaporator receptacle 10 and an evaporator element 12 for evaporating liquid fuel
Data Source
AI summary
A flow-directing insert for a heating device having an evaporator burner, wherein: the evaporator burner has a fan chamber or combustion air pre-chamber, an evaporator holder and a combustion chamber, the evaporator holder has a base wall and a circumferential wall with at least two combustion air passage openings to direct combustion air from the fan chamber or combustion air pre-chamber initially along an exterior of the evaporator holder through the combustion air passage openings into the combustion chamber, the flow-directing insert comprises at least a first region for positioning over at least one of the combustion air passage openings and a second region for fixing in the fan chamber or combustion air pre-chamber of the evaporator burner, the first region being in the shape of a tongue.