A simple NH$3$ vapour compression system has compressor with piston displacement of $2m\frac{3}{m}in,$ a condenser of $12$ bar and evaporating pressure of $2\mathrm{.}5$ bar. The liquid is sub$-$cooled to $20oC$ by soldering the liquid line to suction line. The temperature of vapour leaving the compressor is $100oC,$ heat rejected to compressor cooling water is $5000k\frac{j}{?}hr,$ and volumetric efficiency of compressor is $0\mathrm{.}8.$Compute: capacity; indicated power; and COP of the svstem.