THE INFLUENCE OF THE HEAT-CAPACITY OF COMBUSTION GASES ON THE PERFORMANCE OF A DIESEL-ENGINE

Experimental measurements have been made of cylinder pressure, crank a ngle, ignition delay, exhaust-gas temperature and fuel consumption for a 3.9-litre diesel engine operating on air and on mixtures of oxygen, carbon dioxide, argon and helium. The performance of the engine was e valuated over the available load range at speeds of 1600, 1800 and 200 0 min(-1), and also under maximum load conditions at various speeds. R esults show that the ratio of heat capacities of the gas at the point of fuel injection is the major factor in determining the performance i n comparison with natural air operation. A mixture of oxygen, carbon d ioxide, argon and helium was prepared which gave an engine performance close to that for operation on air. The measured engine output charac teristics did not appear to be influenced by any factor that could una mbiguously be attributed to chemical effects of the components of the mixtures.