Nested Venturi Fuel-Air Mixing Device for Compact Heater Design
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Solution Overview
Problem
Existing fuel-air mixing devices for fan-assisted heaters require increasingly longer venturi lengths to minimize power consumption, leading to larger and less compact designs, which limits modulation width and efficiency.
Innovation Solution
A compact fuel-air mixing device design featuring an outer and inner venturi tube with strategically positioned constrictions and a nozzle, allowing for a shorter pressure recovery distance and laminar flow, enabling efficient fuel-air mixture formation and adjustable throttle for different fuels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single venturi tube is used, then the device structure is simple, but the pressure recovery distance is long leading to larger device size
Solution Approach 1:
The patent applies nesting by placing an inner venturi tube inside an outer venturi tube, creating a compact dual-venturi structure. The inner venturi tube is positioned within the outer venturi tube such that its outlet is located in the constriction area of the outer venturi, allowing pressure recovery to occur over a shorter effective distance while maintaining structural simplicity.
2Use of energy by moving object
If venturi length is increased to minimize power consumption, then power efficiency improves, but device size increases and compactness is lost
Solution Approach 1:
The nested dual-venturi structure allows the system to achieve effective pressure recovery over a shorter overall device length. The inner venturi tube creates a concentrated flow path within the outer venturi, enabling compact design while maintaining the energy efficiency benefits of adequate venturi length.
Solution Approach 2:
The patent transitions from a single-dimensional (single venturi tube) to a multi-dimensional structure by nesting the inner venturi tube within the outer venturi tube. This spatial arrangement in multiple dimensions allows pressure recovery to occur more efficiently within a compact volume, reducing the overall device length while maintaining power efficiency.
3Length of stationary object
If a compact design with shorter pressure recovery distance is implemented, then device size is reduced, but pressure recovery efficiency may be compromised
Solution Approach 1:
The nested configuration of inner and outer venturi tubes creates a synergistic effect where the inner venturi tube's outlet positioned at the outer venturi's constriction point maximizes pressure recovery within a compact distance. The concentric arrangement optimizes fluid flow paths to achieve efficient pressure recovery without requiring excessive device length.
Solution Approach 2:
The patent optimizes specific geometric parameters including the positioning of the inner venturi tube outlet at the outer venturi constriction, the cross-sectional area ratios between inner and outer venturi sections, and the length ratios to achieve optimal pressure recovery efficiency within a compact overall dimensions.
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 design achieves high pressure recovery and compactness, allowing for reliable and efficient fuel-air mixing with adjustable fuel-air ratios, enhancing the safety and reliability of fan-assisted heaters while improving maintenance access and modulation capabilities.
Implementation Method 1
The air is sucked in by the fan, and the gaseous fuel is injected into the air stream in front of the fan. The gaseous fuel is automatically sucked in there due to the negative pressure conditions in the area of the constriction of the venturi.
Implementation Method 2
a nozzle (54) in the area of the second constriction (42) for supplying fuel (28). The pressure lowered at the second constriction (42) of the inner Venturi tube (38) can be regained over a shorter distance
Data Source
Figure 1~2
Figure 3a~4b
Figure 5a~5c
AI summary
The invention relates to a fuel-air mixing device (12), in particular for a heater (10) assisted by a blower (14), comprising an air inlet (52), an outer Venturi tube (36) with a first constriction (40), an inner Venturi tube (38) with a second constriction (42), and a nozzle (54) in the region of the second constriction (42) for supplying fuel (28). It is proposed that the inner Venturi tube (38) be arranged inside the outer Venturi tube (36). The invention also relates to a heater (10) with a burner (16) assisted by a blower (14) and a fuel-air mixing device (12) according to the present invention, which supplies fuel (28), in particular gaseous fuel, to air (26) flowing via a fuel line (32).