Quinn_Inuit

10-16-2018, 06:59 AM

My characters have some dust and enemies they'd like to get off their hands, and they're the type of people who like using one problem to solve another. I tried doing some research on this, but I couldn't find the lower bound heat information that gave me results that made sense. Here's my math so far:

Assume a spherical cow library with an air volume of 3500 cubic meters. Actual square meters = 750.

The air quality is poor, with a PM 2.5 of 150 micrograms/cubic meter comprising primarily cellulose debris from the books. If I'm doing the mass right, the contribution of this component is negligible, but I wanted to get my assumptions out there.

Unknown: weight of book dust. Sawdust weighs 210 kg / cubic meter, but that's tightly packed. I'm assuming that, at the density of your average dust layer, we're looking at minimum a ten-fold decrease in density.

Assumption: the library is poorly maintained, so there's a layer of half a centimeter of dust on most surfaces.

Surface area: there are lots of stacks, but you need space for tables and aisles. I'm assuming 1600 sq. m. of actual dust-containing surface, with maybe a quarter-centimeter thick layer averaged over all affected surfaces.

The library air isn't entirely evacuated. Assume maybe 1000 cubic meters of air gets sucked out, as well as a quarter of the dust.

If I'm doing the math right there, we're looking at about 1 cubic meter of loosely-packed dust, so call it no more than 21 kg. Probably half that, realistically. There's also an upper combustible limit at play, which I can't find anywhere. Too much and there's not enough O2 for the Earth-shattering kaboom. The minimum is around 500g/cu.m.

Once we figure out the mass of dust there, pack it all in a small space and throw in a lit match. How big a boom do we get? That's the other part that's giving me trouble. You've got to figure that only 0.2-20% of the dust actually combusts.

I'm tempted to just assume that I get about 1 kg of dust to actually go boom. That simplifies the math a little and probably does the trick. Unfortunately, I just can't get reasonable numbers for the explosive potential of cellulose dust. My math keeps coming up at way more than the equivalent in TNT, and I know that's wrong.

Any suggestions? Rough approximations are fine.

Assume a spherical cow library with an air volume of 3500 cubic meters. Actual square meters = 750.

The air quality is poor, with a PM 2.5 of 150 micrograms/cubic meter comprising primarily cellulose debris from the books. If I'm doing the mass right, the contribution of this component is negligible, but I wanted to get my assumptions out there.

Unknown: weight of book dust. Sawdust weighs 210 kg / cubic meter, but that's tightly packed. I'm assuming that, at the density of your average dust layer, we're looking at minimum a ten-fold decrease in density.

Assumption: the library is poorly maintained, so there's a layer of half a centimeter of dust on most surfaces.

Surface area: there are lots of stacks, but you need space for tables and aisles. I'm assuming 1600 sq. m. of actual dust-containing surface, with maybe a quarter-centimeter thick layer averaged over all affected surfaces.

The library air isn't entirely evacuated. Assume maybe 1000 cubic meters of air gets sucked out, as well as a quarter of the dust.

If I'm doing the math right there, we're looking at about 1 cubic meter of loosely-packed dust, so call it no more than 21 kg. Probably half that, realistically. There's also an upper combustible limit at play, which I can't find anywhere. Too much and there's not enough O2 for the Earth-shattering kaboom. The minimum is around 500g/cu.m.

Once we figure out the mass of dust there, pack it all in a small space and throw in a lit match. How big a boom do we get? That's the other part that's giving me trouble. You've got to figure that only 0.2-20% of the dust actually combusts.

I'm tempted to just assume that I get about 1 kg of dust to actually go boom. That simplifies the math a little and probably does the trick. Unfortunately, I just can't get reasonable numbers for the explosive potential of cellulose dust. My math keeps coming up at way more than the equivalent in TNT, and I know that's wrong.

Any suggestions? Rough approximations are fine.