BB Fifth Trials

Lab 5: Making Heat and Making Legos


What We Did
This week we wanted to focus on recording heat actually produced by our briquettes, as well as see if we could get them to burn alone (ie. not in the middle of other burning charcoals). So, we took briquette 2B and III (each blocks, one rotted and one made of sawdust and newspaper) and placed them in the large Mustang 60 grill, tindered them with newspaper, and lit them with a blowtorch. From the start time of when the briquettes caught fire, we checked the internal temperature of each briquette at 5 minute intervals. For briquette 2B, it took approximately 15 minutes for the internal temperature to reach 350*F, and after 20 minutes both 2B and III were getting readings of 400*F. At this point, the newspaper had finished burning and the briquettes were self-sustaining their heat (clearly producing heat, but not showing flame). We then added one of our small rotted briquettes into the center of the 400*F briquettes. Success! Our briquettes were able to start the rotted briquette up to an internal temperature of 400*F in just five minutes. The total burn time for the grouping of briquettes was approximately 40 minutes, with the sawdust briquette losing its structural integrity after 30 minutes; the rotted briquettes maintained their shapes until the end of the burn (but did ash apart once prodded as the heat decreased). There was a slight odor emitted from the small rotted briquette when burning, although it was not overpowering.
burning.jpgChecking temp.jpg

We also modified our molds to give them “lego-like” structure in an attempt to see if we could create interlocking briquettes. We compressed a mixture of equal parts sawdust, leaves, and newspaper into our round briquette. The bottom compression stayed very well, however the top prong of each briquette failed to maintain its shape. We did not have time to attempt with the larger block mold.
briquette top.jpgbriquette bottom.jpg

What We Learned
From our burn experiment, we proved that our briquettes can actually sustain relatively high temperatures on their own, without having to sit in a bed of actual briquettes or other burning material as we have previously tried in working with the rocket stove group. Since our thermometer was a candy thermometer that maxed out at 400*F, it is possible that our briquettes were reaching temperatures higher than 400*F, especially with how quickly the reading would spike up when the thermometer was placed into each briquette. This means that theoretically, a bed of only our briquettes could produce and sustain enough heat to actually cook food. However, burn time would continue to be a constraint.

After burn.jpg
Our briquettes post burn – resemble comparable wood charcoal briquettes in shape and ashing

Due to our inability to get the top prong of our “lego” briquettes to maintain its shape, we have decided that it is likely best to drop this idea. This, in conjunction with how well our briquettes burned alone, is enough for us to conclude that we do not wish to pursue any sort of building blocks with this project.

What’s Next
Next week we’ll be doing mass pressing with the left over sawdust/leaves/newspaper material (which has now rotted) to get as many briquettes as possible to attempt to cook food solely using our product. Will will be bringing a small Weber stove this week since he will be unable to attend lab the following week, and Kelly will be bringing old garlic to add to the mixture at the suggestion of Jaclyn, since our research into successful briquettes made in Uganda showed that garlic is commonly used as a binding material.