Dual-Sensor Pellet Grill Control for Low-Temperature Cold Smoke
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Solution Overview
Problem
Current smokers lack the ability to quickly and precisely control temperature variations, particularly for producing cold smoke, which is essential for achieving desirable flavor and texture in grilled foods, due to inherent lag times in temperature control systems and longer pre-heating times required for low-temperature smoke production.
Innovation Solution
A grilling device equipped with an auger feeder system, a firepot, a heating element, a blower, and a digital controller, along with temperature sensors, allows for the precise control of smoke temperature by adjusting the fuel feed rate and oxygen supply, enabling the production of cold smoke at temperatures below 150°F for extended durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a typical temperature control system feedback loop is used to control smoke temperature, then the system can maintain temperature control, but the lag time in the feedback loop causes increased pre-heating time and inability to quickly achieve cold smoke
Solution Approach 1:
The system performs preliminary actions by pre-configuring multiple temperature profiles (e.g., cold smoke at 100°F, medium at 200°F, hot at 300°F) that are ready to be executed immediately. When a user selects a desired temperature, the system can quickly transition to that pre-planned profile without waiting for gradual heating or cooling, thus reducing pre-heating time while maintaining temperature control precision.
Solution Approach 2:
The system dynamically adjusts the feedback loop response based on the desired temperature profile. For cold smoke modes, the system uses a faster response rate to quickly reduce temperature, while for hot smoke modes, it uses a more gradual approach. This dynamic adjustment of control parameters allows the system to overcome the inherent lag time in different operating conditions.
2Temperature
If the fuel feeder completely stops feeding fuel into the firepot to correct temperature overshoot, then the temperature can be reduced, but the existing fuel takes time to burn down and reduce temperature
Solution Approach 1:
The system extracts the unburned fuel from the combustion process by using an auger mechanism to remove excess fuel from the firepot when temperature overshoot is detected. This allows the system to quickly reduce temperature by removing the fuel source rather than waiting for it to burn down naturally, thus reducing the time required to correct temperature overshoot while maintaining precise temperature control.
Solution Approach 2:
The system introduces an intermediary mechanism (the auger fuel removal system) between the fuel supply and combustion process. This intermediary allows for rapid fuel removal without completely stopping the feeding mechanism, enabling smooth and quick temperature adjustment by controlling the amount of fuel present in the firepot rather than relying on natural burn-down time.
3Adaptability or versatility
If different types of solid fuel are used to produce different smoke flavors, then the flavor variety is improved, but each fuel type requires unique temperature control
Solution Approach 1:
The system implements a universal temperature control system that can handle multiple fuel types through a single multi-functional controller. The controller is programmed with knowledge of different fuel characteristics (wood chips, wood pellets, charcoal, etc.) and automatically adjusts parameters such as heating power, fan speed, and auger rotation speed to optimize combustion for each fuel type. This allows the system to maintain precise temperature control across various fuel types without requiring separate control systems for each fuel.
Solution Approach 2:
The system changes operational parameters (heating element power, air supply rate, fuel feed rate) based on the detected or selected fuel type. When a different fuel is introduced, the system adjusts these parameters to match the optimal combustion characteristics for that fuel, enabling versatile smoke flavor production while maintaining relatively simple control logic through parameter adaptation rather than structural complexity.
4Duration of action of stationary object
If the auger feeder system continuously feeds fuel into the firepot, then the combustion is sustained, but the temperature cannot be quickly reduced for cold smoke production
Solution Approach 1:
The system uses periodic action by controlling the auger feeder to deliver fuel in controlled intervals rather than continuously. For cold smoke modes, the auger can be programmed to feed fuel in small periodic amounts or pause feeding temporarily, allowing the firepot temperature to drop quickly while still maintaining enough combustion to produce smoke. This periodic fuel delivery enables both combustion sustainability and rapid temperature adjustment when needed.
Solution Approach 2:
The system dynamically adjusts the auger feeder operation based on real-time temperature feedback and desired smoke conditions. When cold smoke is required, the system rapidly reduces or pauses fuel feeding to allow quick temperature reduction. When sustained combustion is needed, the auger resumes normal feeding. This dynamic control of the fuel delivery mechanism enables the system to switch between combustion sustainability and rapid temperature adjustment as required by different cooking modes.
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
This solution enables the rapid and precise generation of cold smoke, reducing pre-heating times and allowing for customizable temperature regimes, thereby improving the quality and flavor of grilled foods by maintaining ideal smoke conditions for various cooking modes.
Implementation Method 1
a heating element powered by a power source, the heating element providing heat to the interior space of the firepot
Implementation Method 2
a blower powered by the power source, the blower providing oxygen to the interior space of the firepot
Implementation Method 3
configured in connection with the digital controller, the first and second temperature sensors, the heating element, and the blower to combust fuel in the firepot
Data Source
AI summary
A grilling device includes an auger feeder system, a heating element, a blower and a temperature control system. The temperature control system includes at least a first temperature sensor inside the firepot and a second temperature sensor inside a cooking chamber above the firepot. The heating element can also serve as the first temperature sensor. A method for controlling the temperature of the grill can include receiving temperature feedback information from one or more of the temperature sensors and adjusting power provided to the auger feeder system, heating element, and blower. The temperature control system produces cold smoke resulting from the combustion of lignin in solid wood fuel while minimizing temperatures inside the cooking chamber.