12.44: A monatomic ideal g
g1rts3z9ezf)o -l)op as is the working substance for a refrigerator that undergoes the cyclic proc
fpz)e -1r 9 3gtzl)osoess (ABCDA) shown in the PV diagram. The processes are all isochoric or isobaric with pressures between $P_0$ and $2P_0$ and volumes between $V_0$ and 2$V_0$ . What is the coefficient of performance for this refrigerator?