Automating flow rate through condenser based on output temp.

[rumbo]

the huffing isn't related to the output temp fluctuating, its the other way around. the output fluctuates because its huffing.
Huffing can be caused by many things, too fast coolant rate is a big one. Too shallow angle on your liebig. etc etc.
What are you running for a heat source.

Gentlemen, the OP is running a pot still, not a reflux, totally different world

Thanks for the info. My heat source if a 3 ring gas burner. There are separate valves on the 3 rings so it is somewhat adjustable. I had it running flat out for the vinegar run. The water pump was just simply connected to the power source so it was running flat out too. I was getting a thin but constant stream of distillate coming out. Liebig is 45 deg but I can adjust it if I need to. Attached is a picture of my setup.

I will definitely need to sort out the huffing and therefore fluctuating output temp for my project. I could play with the programming a bit to get the temp averaged out over a 20 second period or similar, but my gut feeling is that for it to work, the still will need to be settled as much as possible. I realise that it will behave differently on an alcohol run to my vinegar run but did expect some huffing due to the length of my condensor. I will be running my sacrificial run over the next couple of days so i'll see how that goes. Might put some SS scrubber strands inside the condensor during the run do see if it makes a difference. Do they have to be at the top of the condensor or can I just stuff them up the end where the spirit comes out?

I also have a buck which I can use to dial the voltage up or down to the pump. This is a bit of a crude way to control pump speed but should give me an indication if slowing the pump speed helps with the huffing.

[rumbo]

Just an update to this. I tried varying the voltage to control the speed of the motor. It actually worked very well. I found that if I start off at 7.2V it gives me an output water temp from condensor of 50 degrees during a stripping run with my 3 ring burner running flat out (once the run has started properly). As the run progresses and my reservoir water warms up a bit, the output water temp rises about 1 degree every 15 mins. I then found that 1/2 turn of the screw on my buck corresponds to an increase in voltage of 0.6V which happended to conicide with an increase of water flow to bring the output temp back down 1 degree for my particular setup. I think that the arduino controlled flow based on output temp will work well..

All relates back to one premise though, that we are trying to keep a consistent output temp throughout the run for best efficiency. The next question is - what output temp should we be aiming for??? The figure of 50 degrees C (about 120 f) has been mentioned - is this figure well recognised as a target? Or will if vary greatly between different setups?