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Calculating time to reduce alcohol in wine using heating method
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[QUOTE="Chestermiller, post: 6866671, member: 345636"] This is follow up to my post # 54. According to this online calculator [URL]https://www.handymath.com/cgi-bin/ethanolwater3.cgi?spcfgrv=&conc=&concv=15&submit=Calculate&volwght=&calcvolwght=[/URL], for 15% ethanol by volume, the mass fraction ethanol in the wine is 12.1%. For a molecular weight of 46 g/mole for ethanol and 18 g/mole water, this breaks down to an initial mole fraction ethanol of ##x_0=0.051## for the ethanol and ##(1-x_0)=0.946## for the water. This reduces to a weighted average molecular weight of 17.1 for the wine mixture. So, if we have 250 g of wine initially (assuming a typical initial wine density of 1.0 g/cc), the initial number of moles of wine in the beaker is ##m_0=14.6##. At 80 C (assumed operating temperature), according to the steam tables,, the term ##\frac{P^*_W}{RT}## in the denominator of Eqn. 11 for the characteristic time for ethanol removal is ##1.63x10^{-5}\ moles/cc##. Assuming that the 250 ml wine is contained in a 500 ml "beaker" of diameter 3", the area of the heat transfer surface is A = 45.6 cm^2. Substituting these values into Eqn. 11 of post #54 for the characteristic ethanol removal time ##\tau\ (sec)##, we obtain $$\tau=\frac{19700}{7k_E-k_w}$$As noted in post #54, the mass transfer coefficients in the denominator are highly uncertain, and, because of the higher diffusion coefficient of water than of ethanol in air, the value of ##k_W## is expected to be a little higher than ##k_E##. Individual k values tend tend to range from about 0.1 cm/sec too about 10 cam/sec. My best crude guess for the value of denominator of this equation would be about 4 cm/sec. Substituting this into the above equation yield a value of $$\tau=\frac{19700}{4}=4900\ sec= 80\ min$$So we are probably looking at times of 10's of minutes to hours for the ethanol concentration to be reduced to desired levels in the wine. [/QUOTE]
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Calculating time to reduce alcohol in wine using heating method
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