Ember Generator for Fire Behavior Research

The goal of this project was to create an ember generating device which mimics the output of firebrands at the wildland urban interface during wildfires. This ember generator will be used by researchers and students at the University of Idaho's College of Natural Resources in fire behavior studies and testing of fire-resistant materials.

=Problem Definition= Ember generation is a byproduct of fires. Wildfires are expanded through the emission of embers which start spot fires downwind. Embers emitted from wildfires can cause structure fires at the wildland urban interface. Understanding how these embers interact with natural and human-made material is important in stopping the spread of wildfires and designing fire-resistant construction materials for buildings. Researchers need a way of observing and testing controlled ember-structure interactions that is realistic to wildfire scenarios and can be scaled down and made safe.

Background
The National Institute of Standards and Technology (NIST) developed a Standard Firebrand Generator (The Dragon) and later a Reduced‐Scale Continuous Feed Firebrand Generator (The Baby Dragon). We used their Baby Dragon schematic, shown here, as a starting point for our design but made key changes to meet our client's requirements including a more compact design that allowed for easy transportation and remote controls.

Value Proposition Statement
Wildfires cost the United States billions of dollars in damage and human lives every year. A better understanding of how these fires interact with materials is needed in order to prevent or mitigate damage. It has been difficult to replicate wildfire scenarios in a lab setting in the past. Our ember generator was designed to output firebrands at a flux equivalent to that seen in wildfires. This will enable researchers in the College of Natural Resources to study how embers interact with different materials in a safe and controlled lab setting.

Deliverables
The end product of this project is a fully functional ember generator capable of outputting a steady stream of embers for 15 minutes without refueling. In addition, we will deliver a final report that details our design process, several presentations, prototype drawing to our client, a tutorial video on how to use the ember generator, an expo presentation, and this Wikipage.

Specifications
=Design Considerations= Our design was made to follow the specifications given to us by our clients, listed above. In the future, our ember generator will be connected to a wind generator, so our design kept that in mind. safety was an upmost concern, our design has several safeguards in place including heat resistant stainless steel stovepipe, measures to prevent multiple airflows to reduce possible fire paths, and an emergency shutdown system.

Woodchip Feed System
The initial design for the woodchip feeding system was a motorized shaft with four metal pegs which held silicon fins that filled the diameter of the square hole between a hopper that contained the woodchips and the stove pipe that led to the propane flame. Silicon was chosen because it is heat resistant and flexible, reducing clogging from larger woodchips.

=Project Learning= Our client gave us access to the Idaho Fire Lab, a concrete building used by the College of Natural Resources to study fire behavior, throughout the semester to test our designs for proper ember generation. We also had access to the Engineering Capstone Design Suites where we built our ember generator and tested different design features that weren't reliant on fire testing.

Spring 2021 Testing
In the spring we built the frame on the ember generator. The frame holds the propane tank and ember generator which consists of galvanized and stainless steel stove pipe, a blower, a motorized auger, a hopper that holds 7 lbs. of woodchips (enough to feed the fire for 15 minutes with an auger speed of 12rpm), and a propane torch connected to the propane tank, in all measuring 48"x16"x40".

The auger system was chosen after testing the wheel design over winter break at home and finding that it jammed easily. The funnel system in the hopper was chosen after testing different designs at the Design Suite using cardboard models. The funnel narrows the diameter of the hopper to 3 inches and allows the woodchips to fall continuously onto the auger without getting jammed, but slowly enough to allow the auger to carry woodchips evenly. The auger caught on the ridges of the stovepipe, so a smoother stove pipe insert was added under the auger. During testing it was also found that big woodchips caused the system to jam and took much longer to burn, so it was decided to only use small (1cm or less) woodchips.

- embers are capable of catching materials on fire → Embers caught straw on fire, as seen in the photos above.

=Team Members=

=Additional Documentation=

Project Schedule Project Schedule

Meeting Minutes Minutes Folder

Presentations

Client Interview