$1)$ It is desired to concentrate an aqueous solution of NaCl from $7\%$ to $35\%$ by mass in a

simple evaporator. The process consists of two stages, a vaporization stage in the

evaporator and a condensation stage in a heat exchanger.

Evaporator: In this stage of the process the aim is to concentrate the salt, for this $100$

Kg$/$h of the aqueous NaCl solution at the initial concentration and a temperature of $26\backslash$deg C

which will be the reference temperature. At the evaporator outlet the temperature of the

mixture is $70\backslash$deg C$.$

Heat exchanger: In this stage the water vapor that leaves the evaporator is

heated with cold liquid water entering the system. Inside the exchanger there is no

contact between cold water and hot water. Hot water inlet temperature

is $70\backslash$deg C and the hot water outlet temperature is $58\backslash$deg C$.$ The temperature of

Cold water inlet is $25\backslash$deg C and outlet temperature is $38\backslash$deg C$.$

To design the process, the block diagram must be made and find:

a$)$ The heat that must be supplied to the evaporator $($assume that there are no heat losses$).$

energy$)$

b$)$ The mass of cooling water necessary to condense the water vapor $($the

exchanger operates adiabatically$)$

$*$For heat capacities use somatic equations. in the evaporator

Assume that the mixture of NaCl and water has the same heat capacity as water.

pure

$*$The process operates at constant pressure and is in a steady state.