During the trial of a single oil engine, cylinder diameter 20 cm, stroke 28 cm, working on the two-stroke cycle, and firing every cycle, the following observations were made: Duration of trial=1 h, total fuel used=4.22 kg, calorific value of fuel-44670 kJ/kg, proportion of hydrogen in fuel-15%, total number of revolutions=21,000, mean effective pressure=2.74 bar, net brake load applied to a drum of 100 cm diameter-600 N, total mass of cooling water circulated = 495 kg, temperature of cooling water: inlet 13C, outlet 38C, air used = 135 kg, temperature of air in test room= 20C, temperature of exhaust gases=370C. Assume c,, of gases = 1.005 kJ/kg.K, c, of steam = 2.093 kJ/kg.K at atmospheric pressure. Calculate the thermal efficiency and draw up the heat balance sheet. [IES, 1997]