_______________________________________________________________________________________________

Home

The time to heat or cool a fixed mass of liquid inside a batch reactor is calculated.The primary simplification here is that both the utility and process heat capacity as well as the overall heat transfer coefficientare assumed constant throughout.

Liquid Jacket Utility: The jacket is a 'one pass' with a fixed flowrate of liquid at inlet temperature T1.A closed form solution has been developed and is shown at the bottom of the page.

Steam Jacket Utility: With steam at specified inlet pressure (assumed to be saturated) the time to heat is basedon isothermal condensation in the jacket with as much steam passing through the trap as heat transfer will allow.Simple closed form solution below.

_______________________________________________________________________________________________

INPUT DATA

Input Units (or pick and choose)

Metric

British

Recalculate if changeindividual unitselections

Reactor Contents Process Data

Liquid or Steam as jacket utility Steam

Initial temperature, T0 25

Final temperature, Tf 60

Heat capacity, Cp 1.9

Mass of liquid, m 13500

Jacket and Utility Liquid Data

Overall HX coefficient, U 370

Heat transfer area, A 35

Jacket liquid inlet temperature, T170 Liquid Utility

Jacket liquid flowrate, W 982 Liquid Utility

Jacket liquid heat capacity, C 4.186 Liquid Utility

Inlet steam pressure, P0 10.0 Steam Utility

_______________________________________________________________________________________________

RESULTS

Heating / Cooling Time minutes

Calculate Heat/Cool time - Batch reactor http://www.eng-calculations.com/heat time - batch reactor.aspx

1 di 2 24/01/2014 14:52

_______________________________________________________________________________________________

EQUATIONS (Liquid in Jacket)

Heat input to reactor at T = Heat loss by utility liquid with inlet temperature T1 (specified) and outlet temperature T2(unknown)

Solving for the unknown jacket outlet temperature T2

The rate of temperature change of the liquid inside the vessel is given by

Solving the above two equations to get process temperature as a function of time:

Finally, solving for time t where T = Tf (with T = T0 at t = 0)

EQUATIONS (Steam in Jacket)

Calculate Heat/Cool time - Batch reactor http://www.eng-calculations.com/heat time - batch reactor.aspx

2 di 2 24/01/2014 14:52