Saturday, June 16, 2007

Viscosity Testing - Final Day

So today is the final day of testing - I woke up early so I could work on the final sets of analysis before heading off to the Pirate Fest.

So, what did I learn?

I regained respect for an old lesson: what isn't known is often more important than what is known. Figuring out what you don't know is a very difficult task.

Preliminary experimental conclusions:
I heated Canola oil at 75-85C for 5 days, the viscosity increased by approximately 5% -- not terribly much, all things considered. The presence of metal tubes had no immediately noticeable effect on vegetable oil viscosity. All heated samples experienced an increased viscosity of about 5%.

I was surprised to note that the the oil exposed to stainless steel and aluminum took on a slightly darker color after 5 days. It should be noted, however, that the oil exposed to copper retained the same color as the control samples. I was surprised by the stainless steel, but the aluminum was something I expected. I also expected copper to cause a color change.

I haven't completed the complete numerical analysis of the data, so it's more than possible that I will be able to observe more trends as I start crunching numbers. I also have a few more samples to analyze - I'm especially interested to see what happens with the oil from my fuel tank.

After doing all the number crunching, I've found that copper doesn't appear to cause any significant changes in vegetable oil viscosity alone. All my heated samples increased viscosity by about 5%.

When I sampled oil from my actual tank over several days, I discovered that the effect of the backflowed diesel (in my two-tank system) overwhelmed any evaporative effect from heating. My tank samples were all significantly less viscous than any of my experimental samples - 10-20% less viscous.

The takeaway here is that I wasn't able to find a significant change in viscosity or detect polymerization. Additionally, in real-world applications, even a little bit of diesel has a significantly greater effect on viscosity than evaporation or polymerization.

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