Obtain an expression for the capacity of a refrigeration system (tonnage) in terms of the rate of upper and lower pressure limits, expansion index (n), vc / vs, (vc = clearance volume and vs = swept volume), N (rpm), vc, v1 (specific volume at the inlet to compressor) and the refrigeration effect (h1 – h4). If the pressure ratio is 6.5, n = 1.1, vc / vs = 0.025, N = 900, vs = 600 cc, v1 = 0.078 m3/kg and refrigeration effect = 150 kJ/kg, calculate the capacity of the system.