On:
croweater wrote:Here's the strange thing the last jar took 3 times as long or more than any other and yet most of it came out at above 60%.
Here's why [Physics nerds, if I'm wrong on this please correct me. :violence-stickwhack: ]. The %ABV (percentage alcohol) of the wash in your boiler is dropping off towards the end of your run, so the boiling point of your charge is getting closer and closer to 100 degrees. As you get to the end it takes more and more energy to keep the wash boiling. However, the power applied to the boiler through your heating element remains fixed thoughout the whole run. As a result, as you approach the end of the run your wash produces less and less vapour and your flow rate drops off.
If you were to do a run of pure water you'd find that the flow rate is much slower than a water/alcohol mix.
There's an up side. When you're applying constant heat throughout a run, the more energy it takes to boil the mix, the less energy it takes to condense the vapour coming off that mix because there's simply less of it. Think of it this way: alcohol's lower boiling point is a vapourising dream but a condensing curse. Its lower boiling point means that it loves to get out of a hot boiler as vapour but because there's so much vapour it's difficult to turn it all turn back into liquid.
You notice this a lot more on a pot still stripping run, where (if you keep the heat constant throughout the run) as you approach wash and vapour temps of 100 degrees the output flow rate drops off with the alcohol percentage.