$18$

Problem $05\mathrm{.}179-$ Charging process

$10$

points

Submarines change their depth by adding or removing air from rigid ballast tanks, thereby displacing seawater in the tanks. Consider a submarine that has a $700-m^3$ air$-$ballast tank originally partially filled with $100m^3$ of air at $1500$ kPa and $15C.$ For the submarine to surface, air at $1500$ kPa and $20C$ is pumped into the ballast tank until it is entirely filled with air. The seawater leaves the tank at $15C.$ Presume that air is added to the tank in such a way that the temperature and pressure of the air in the tank remain constant. Determine the final mass of the air in the ballast tank under this condition. Also determine the total heat transfer while the tank is being filled in this manner. The gas constant of air is

$R=0\mathrm{.}287$kPa$*\frac{m^3}{k}g*K.$ The specific heats of air at room temperature are

$c_P=1\mathrm{.}005k\frac{J}{k}g*K$ and $c_v=0\mathrm{.}718k\frac{J}{k}g*K.$ The specific volume of water is taken $0\mathrm{.}001\frac{m^3}{k}g.$

The final mass of the air in the ballast tank is

kg$.$

The total heat transfer is

$kJ.$