Instantaneous RR measurement

[Maritimer]

In a VM still, all of the vapour that gets to the reflux condenser is turned into liquid, and the part that goes to the product condenser is turned into a liquid in that path. So, as I understand it, the reflux ratio is:

RR = [mass of reflux liquid]/[(mass of reflux liquid)+(mass of product liquid)]

Now on page 44 of The Compleat Distiller, this would seem to be the definition of the product ratio, and the definition of the reflux ratio would seem to be the percentage of the vapour that is condensed in the reflux condenser out of the total vapour entering it. If any vapour is not condensensed in the reflux condenser, then it must be going to the product condenser, otherwise you would have vapour venting from the reflux condenser.

So, is there really any difference between Reflux Ratio and Product Ratio in a VM still?

Assuming that my definition is correct, then the rate of liquid condensed in each condenser would be equal to:

liquid condensation rate = (rate of coolant flow) X (temperature difference between in and out coolant) X (specific heat of water [=1]) / (latent heat of vapourisation of vapour)

But in a VM still, the same water flows at the same rate through the product and the reflux condensers, and the same vapour is going into both condensers, so when you plug the two liquids into the RR equation and cancel out the coolant flow rates and the LHV, you get:

RR = [temp diff between reflux in and out]/[(temp diff between reflux in and out)+(temp diff between product in and product out)]

or, since the product out and reflux in are the same:

RR= (temp diff between reflux in and out)/(temp diff between input to product condenser and output of reflux condenser)

Any cooling of the condensate would cause a small error, but since the specific heat of the liquid is so much tinier than the latent heat of vapourisation, it can probably be ignored.

So, if I install temperature sensors at the input to the product condenser, in the line between the product and reflux condensers, and at the output of the reflux condenser, could I measure the instantaneous reflux ratio?

M