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Heat Transfer during Mixing (Just need confirmation!) 
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#1
Apr1012, 02:57 PM

P: 1

Hi Everybody!
This is my first post on this forum! Anyways... I have a problem where I think I have the correct answer, however I would like some confirmation. Problem I have TWO inlet streams (m1, m2) that connect to each other into ONE outlet stream (m3). I need to solve m1 and m2 (See below for known parameters) Therefore the equations that I am using are: m1 + m2 = m3 and Q1 + Q2 = Q3 Known Parameters T1, T2, T3 and m3 (the total outlet flow) I need to determine the mass flow of the inlet streams (i.e. m1 and m2). My Solution Q1 + Q2 = Q3 m1cp(Tr  T1) + m2cp(Tr  T2) = m3cp(T3Tr) *Tr is the reference point where the two inlet streams meet and mix together* Since no heat is being generated, only mixed, I can assume Tr will just be a weighted average of m1 and m2 therefore: Tr = (m1T1 + m2T2) / m3 Since I only need a ballpark figure and the temperature differences aren't too far apart, I assume the specific heat values (cp) to be equal so I can cancel them out. What I'm left with is m1(TrT1) + (m3m1)(TrT2) = m3cp(T3Tr) All I have to do is plug in the equation for Tr and eventually I'll get m1 = m3(T3T2) / (T1T2) Final Statements I can do the last steps myself so to save your time, I only need confirmation on: 1) Is my Q1 + Q2 = Q3 equation correct? 2) Is my Tr equation correct? Thank You! Remember: You're all f**king awesome, dont let nobody tell you otherwise! 


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