Exercises on Energy Balances
Exercises on Energy balances I 5.1 Sensible energy change Calculate the enthalpy change associated with the following
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Exercises on Energy balances I
5.1 Sensible energy change Calculate the enthalpy change associated with the following processes: (a) m-cresol is heated from 25°C to 100°C (b) ethylene glycol is cooled from 20°C to
10°C (c) succinic acid is heated from 15°C to 120°C and (d) air is cooled from 150°C to 65°C
5.2 Heat of vaporization Nitrogen is sometimes bubbled into fermenters to maintain anaerobic conditions. It does not react, and leaves in the fermenter off-gas. However it can strip water from the fermenter, so that water vapor also leaves in the off-gas. In a continuous fermenter operated at 33°C, 20 g/h water is evaporated in this way. How much heat must be put into the system to compensate for evaporative cooling?
5.4 Pre-heating nutrient medium Steam is used to heat nutrient medium in a continuous-flow process. Saturated steam at 150°C enters a coil on the outside of the heating vessel and is completely condensed. Medium enters the vessel at 15°C and leaves at 44°C Heat losses from the jacket to the surroundings are estimated as 0.22 kW. If the flow rate of medium is 3250 kg/h and the heat capacity is Cp = 0.9 cal /g/°C, how much steam is required?