7. A system consists of 2 kg of carbon dioxide gas initially at statel, where p=lbar, T=300K.The system undergoes a power cycle consisting of the following processes: Process 1-2: Constant volume to p2, p2> P1 Process 2-3: Expansion with pv1.28 = constant Process 3-1: Constant-pressure compression Assuming the ideal gas model and neglecting kinetic and potential energy effects, (a) Sketch the cycle on a p-v diagram. (b) Using EES, plot the thermal efficiency versus p2/p ranging from 1.05 to 4.