To rapidly cool white wine grape musts for premium quality white wine pro- duction, dry ice is added to the must immediately after crushing the grapes. calculate the amount of dry ice per kg of must required to cool the must from 25 °c to 10°c if the heat capacity of grapes is 3.6 kj/kg"c, the enthalpy of dry ice is -31.9 kj/kg and the enthalpy of co2 gas at 10 °c and 1 atm pressure is 380.9 kj/kg.

A2-m rigid tank initially contains saturated water vapor at 100 kpa. the tank is connected to a supply line through a valve. steam is flowing in the supply line at 600 kpa and 300 c. the valve is opened, and steam is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. a thermometer placed in the tank indicates that the temperature at the final state is 200°c. determine (a) the mass of steam that has entered the tank (b) the amount of heat transfer.