2000 kg/h of milk is sterilized in a steam infusion sterilizer. The milk is heated to 145 ℃ by introducing it into the steam infusion chamber H and then is cooled quickly by flashing in the flash vessel F. The vapor that flashes off in the vessel F is condensed in the condenser C by direct contact of the vapor with cooling water. To avoid dilution of the milk, the pressure in the vessel F must be such that the rate at which vapor flashes off in the vessel F is equal to the steam that is added in the vessel H. Calculate the cooling water flow rate in the condenser that will give the required pressure in the flash vessel. The following data are given: The temperature of the milk at the inlet of H is 40 ℃, the temperature of the cooling water at the inlet of the condenser is 20 ℃, the steam introduced into the chamber H is saturated at 475.8 kPa pressure, and the heat capacity of the milk is 3.8 kJ/kg ℃ at the inlet of the infusion chamber and 4 kJ/kg ℃ at the exit of the infusion chamber. b. For quick preparation of a cup of hot chocolate in a cafeteria, cocoa powder and sugar are added in a cup of water and the solution is heated by direct steam injection. If the initial temperature of all the ingredients is 15 ℃, the final temperature is 95℃, the mass of the solution is 150g initially, and the heat capacity of the solution is 3.8 kJ/kg ℃, calculate how much saturated steam at 110 ℃ will be used. State your assumptions. Steam
2000 kg/h of milk is sterilized in a steam infusion sterilizer. The milk is heated to 145
℃ by introducing it into the steam infusion chamber H and then is cooled quickly by
flashing in the flash vessel F. The vapor that flashes off in the vessel F is condensed in
the condenser C by direct contact of the vapor with cooling water. To avoid dilution of
the milk, the pressure in the vessel F must be such that the rate at which vapor flashes
off in the vessel F is equal to the steam that is added in the vessel H. Calculate the
cooling water flow rate in the condenser that will give the required pressure in the flash
vessel. The following data are given: The temperature of the milk at the inlet of H is 40
℃, the temperature of the cooling water at the inlet of the condenser is 20 ℃, the steam
introduced into the chamber H is saturated at 475.8 kPa pressure, and the heat capacity
of the milk is 3.8 kJ/kg ℃ at the inlet of the infusion chamber and 4 kJ/kg ℃ at the exit
of the infusion chamber.
b. For quick preparation of a cup of hot chocolate in a cafeteria, cocoa powder and sugar
are added in a cup of water and the solution is heated by direct steam injection. If the
initial temperature of all the ingredients is 15 ℃, the final temperature is 95℃, the mass
of the solution is 150g initially, and the heat capacity of the solution is 3.8 kJ/kg ℃,
calculate how much saturated steam at 110 ℃ will be used. State your assumptions.
Steam
H F C
Milk in
Milk and
steam
Milk out
vapor
Cooling
water in
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