BB 4th Trials

Lab 4: Getting Specific and Hand Pressing


What We Did
This week we shifted our focus toward creating a set of metrics to use for the remainder of the quarter, in order to have quantifiable measurements for each type briquette made, efficiency of burning, etc. Measurements were taken using a standard ruler and a scale borrowed from the food science department (using a conversion factor of 1oz=28.35g).We recorded the following values for our cylindrical (1-6) and box (1B-2B) briquettes made last week, as well as for a two-week-old briquette (non rotted materials; labeled 1A).

Known radius of cylinder – 2.04cm
Known W/L of box – 4.7cm/7.0cm

Briquette Height (cm) Volume (cm^3) Mass (g) Density (g/cm^3)
1 2.9 37.9 11.34 0.299
2 2.9 37.9 11.34 0.299
3 2.5 32.7 9.92 0.303
4 2.0 26.15 7.09 0.271
5 3.7 48.37 14.18 0.293
6 2.3 30.07 5.67 0.189
1A 4.0 52.30 12.76 0.244
1B 5.3 174.37 59.50 0.341
2B 4.3 141.47 56.70 0.401

We also made a new, small batch of briquettes using purely newspapers, water and sawdust collected from the Hangar. This was new since we have yet to been able to experiment with sawdust. We used equal parts paper and dust (184.28g each) to prepare the mixture.

We also successfully managed to hand-press the materials without the use of the hydraulic press. This was done by completely loading each die with our mixture, pressing down the insert until flush with the top of the mould, and using a steel bar to load body weight onto the insert until it was depressed as far as possible. We alternated between this method and the original use of the hydraulic press for both moulds, so we can compare their shape retention, size, and density next week.

image.jpgpole press.JPGsaw briquettes.JPG

What We Learned
We discovered that our briquettes made from the rotted material had roughly the same density, which was to be expected since they were all made using a uniform process. However, in comparison to the two week old briquette, they are slightly denser (for the relative height, as seen in comparing 1A to 5) than the non-rotted briquettes, which could be indicative of the rotted material being less able of retaining original shape, and thus easier to compress into solid briquettes.

briquette comparison.JPG
Original (left) and rotted (right) material briquettes

Additionally, we found that sawdust (for now) appears to be a great binder for the briquettes! The fact that we were able to hand press some this week suggests that a simpler composition may be more effective at retaining shape, although burning ability is not yet known.

What’s Next
We will be burning our rotted briquettes from last week this Friday at Jake’s house, in an attempt to see if we can treat them as regular coals alongside normal cooking briquettes. We will be saving one cylindrical and one box briquette, however, to burn next week as a comparison to the sawdust briquettes, both hand and hydraulic pressed. We will be measuring time to heat, burn time, temperature, and observational properties such as structure, ability to flame, etc. In lab on Tuesday we will see how well the sawdust burns and if they burn well we will try to make approximately thirty so we can see how they burn without the use of store bought charcoal.

Burn Briquettes Burn!

What We Did
We burned briquettes 1A, 1, 2, and 2A in a bed of regular charcoal briquettes at Jake’s house in order to simulate the environment in which we would like our briquettes to be used (you know, for cooking). While the wind made things difficult for a while, we managed to get the bed of coals hot enough to add our briquettes. We started with 1A (the non-rotted briquette), and found that it lasted for approximately 25 minutes before falling apart. Briquettes 1 & 2 burned much more successfully, each lasting approximately 45 minutes, completely retaining a coal-like shape while merely shrinking in size. When prodded, these briquettes did not flake apart like 1A had. Briquette 2A (our block-shaped briquette) lasted around 1 hour, mostly maintaining its shape, except along a fault line that existed prior to burning. Each of the briquettes ashed and sparked like a regular coal might, and briquettes 1, 2, and 2A all caught fire and maintained a flame (and could be coaxed to do so again with a bit of blowing).

What We Learned
Based on the burn times of each briquette, it appears that the rotted briquettes burned better, most likely due to the density of the material and how well-compressed each one was. Since 1, 2, and 2A all burned longer than 30 minutes (the standard burn time for briquettes in Uganda), we consider them to be a potential viable option, pending on the actual temperatures we record next week.

We estimate that our small briquettes last less than half the time of typical wood charcoal, and that our larger block briquettes last half as long (or more) than wood charcoal briquettes.

What’s Next
Beyond what we will be testing next week (listed above), we would be interested in creating a surplus of briquettes to attempt to burn them without using the support of actual charcoal briquettes, which would allow us to determine if they are self-sufficient in creating heat.