Parallel Tube Infrared Burner Cooling to Prevent Pre-Ignition
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Solution Overview
Problem
Conventional radiant infrared burners for outdoor barbeque grills face limitations such as limited gas flow turn down ratio, susceptibility to extinguishment in windy conditions, inefficient heat transfer, high pressure drop, high fabrication costs, and pre-ignition issues due to primary air auto-ignition at low ambient temperatures, along with material durability challenges from high temperatures.
Innovation Solution
A burner design utilizing convective heat transfer with small, vertically oriented burner ports under a horizontal surface, incorporating secondary air for cooling and multiple radiation heat shields to prevent pre-ignition, achieve efficient heat transfer, and maintain compact construction, while allowing for high gas flow turn down ratio and resistance to windy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional radiant infrared burners are used, then infrared radiation is generated, but pre-ignition occurs due to primary air auto-ignition at low ambient temperatures
Solution Approach 1:
The patent extracts the harmful primary air-gas mixture from the combustion zone by introducing secondary air that flows around the burner tube, effectively separating the ignition-prone mixture from the high-temperature zone and preventing pre-ignition
Solution Approach 2:
Secondary air acts as an intermediary cooling medium that flows between the burner tube and the combustion zone, providing thermal protection to the burner tube while maintaining combustion efficiency
2Temperature
If radiant burners operate at high temperatures (1600-1800°F), then infrared radiation is produced, but material longevity is compromised due to thermal cycles and corrosion
Solution Approach 1:
Secondary air serves as a protective intermediary that cools the burner tube through convective heat transfer, reducing thermal stress and corrosion while allowing the emitter to maintain high operating temperatures for effective infrared radiation
Solution Approach 2:
The patent replaces radiant heat transfer with convective heat transfer by directing hot gas vertically onto the emitter surface, achieving efficient heat transfer at lower burner tube temperatures and extending material life
3Device complexity
If all air for combustion is mixed with gas prior to burner admission, then combustion is simplified, but auto-ignition risk increases due to low ambient temperature sensitivity
Solution Approach 1:
The patent segments the air supply into primary air (mixed with gas) and secondary air (introduced separately around the burner tube), creating distinct functional zones that prevent auto-ignition while maintaining combustion efficiency
Solution Approach 2:
The harmful auto-ignition-prone primary air-gas mixture is extracted from the high-temperature zone by introducing secondary air, separating the mixing function from the combustion zone to prevent premature ignition
4Stability of the object's composition
If radiant burners are designed with large box depth for complete mixing, then uniform heat distribution is achieved, but device size increases
Solution Approach 1:
The patent replaces the need for deep mixing chambers with convective heat transfer, directing hot gas vertically onto the emitter surface to achieve rapid, uniform heat distribution in a compact configuration
Solution Approach 2:
The patent transitions from horizontal mixing in a deep box to vertical convective flow, utilizing the vertical dimension for heat transfer and achieving compact horizontal footprint while maintaining effective heat distribution
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 solution enhances heat transfer efficiency, prevents pre-ignition, reduces operating temperatures, and maintains a compact design, resulting in improved thermal response, reduced maintenance, and lower costs without internal fires.
Implementation Method 1
A burner design utilizing convective heat transfer with small, vertically oriented burner ports under a horizontal surface
Implementation Method 2
admission of secondary air for combustion is substantially remote to the burner ports and the depth of the box is considerable to allow complete and uniform mixing to evenly heat the re-emitter
Data Source
AI summary
A firebox for a gas grill with an infrared re-emitter surface at the top, at least one heat shield at the bottom, and sidewalls intermediate between the heat shields and the emitter plate forming a box like structure in which multiple small cross sectional area tubes with gas burner ports on the top or sides are disposed in an array between the heat shield and the emitter plate. The heat shield below the burner tubes has openings disposed below the burner tubes to admit secondary combustion air and provide cooling of the burner tubes preventing pre-ignition.