Lets Start with Diffrent Loading Calculation
Step : 1
1. Heat Loss to Atmosphere : Surface Area m² X Delta (Tavg – Troom)ºC x 0.32 = Q1 kcal/ hr
2. Cooling Load : Volume of liquid (lits) x Delta (Tstart-Tend)ºC/Time (hr) = Q2 kcal/hr
3. Heat evolved during Chemical process/ Fermentation : Q3 kcal/hr
Total Heat to be Removed = Cooling Load = Q = (Q1 + Q2 + Q3) X factor of safety
Please note Unit of Measurement carefully
for Q3, what process do you follow in your vessel, you need to find out the Load.
Step : 2
Calculate LMTD {Log Mean Temperature}
DT1 = TmediaStart – TcoolenEnd
DT2 = TmediaEnd – TcoolentStart
LMTD = (DT1-DT2)/ ln(DT1-DT2)
Step : 3
Calculate Overall heat Transfer co-efficient & Surface Area Required
Q = U A LMTD
Hence, A = Q / (U x LMTD)
U, Over all heat transfer co-efficient : 100-250 Kcal/ hr ºC m², this is mainly depends uppon what type of jacket do you use, limped coil or limped jacket or profile sheets or laser welded jacket etc. you need to have some co-relation to evaluate this if the construction of jacket is non-standard. for standard type of jacket, you can get more info on following link
http://www.cheresources.com/jacketed_vessel_design.shtml
and if nothing works, ask me 🙂
Step : 4
Calculate amount of Cooling media needed for cooling
Now here is a trick, their are two type of coolent, one, they cool by their latent heat (e.g Ammonia) or two, they cool by dropping their temperature (e.g glycol water)
for First option, we need to consider Enthalpy of latent heat, devide Q by this, and you will get mass flow, for Second type follow following equation
Q = m . cp. DT (Tstartcoolent – TendCoolent)
Make sure you get these enthalpies at the working temperature, refer Perry’s handbook, or ask your cooling supplier for detail physical properties, as these properties changes with pressure & temperature, for water mix coolent like glycol, the properties changes with concentation of media
I hope this is sufficient in-sight, in case of help, let me know
