Cans of baked beans in tomato sauce are to be sterilised by steam for a time per

Question

Cans of baked beans in tomato sauce are to be sterilised by steam for a time period of 60 seconds. The cans are small cylinders. The cans have to be heated from an initial temperature of 25°C till the centre temperature reaches a minimum value of 112°C during the time period for successful sterilisation, but must not exceed 126°C.

Baked bean and sauce thermal conductivity = 670 W m-1 K-1
Baked bean and sauce specific heat capacity = 3600 J kg-1 K-1
Can height (L) = 65 mm
Can radius (r) = 22.5 mm
Overall heat transfer coefficient between
steam and can = 1500 W m-2 K-1
Steam temperature = 130 °C
(a) Assuming there is perfect mixing within the can during heating (no temperature distribution within the can), provide a recommendation from your calculations whether or not the proposed heating time will be satisfactory.
[8 marks]
(b) A different variety of tomato is to be used for making the sauce. This causes the tomato sauce to thicken to a point where there is no mixing induced in the can during heating (acts as a solid body). Calculate the affect this has on the maximum centre temperature during the same heating period of 60 seconds. Is the heating time satisfactory? Assume the thermodynamic properties of the baked beans and tomato sauce do not change. Schack charts are provided for an infinite slab and cylinder.
[12 marks]

Explanation / Answer

check these sites... www.massbalance.org/about/ www.nichols.edu/departments/glacier/mb.htm http://serc.carleton.edu/introgeo/mathstatmodels/examples/MassBalance.html

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