APPLICATION OF AVAILABILITY AND ENERGY BALANCES TO A DIESEL ENGINE.

The maximum power that can be extracted from an engine operating at a given condition was determined by means of analyses based on the first and second laws of thermodynamics. These analyses were applied to a heavy-duty single-cylinder open-chamber diesel engine operated at constant speed. Over the range of operating conditions investigated, the second-law efficiency (ratio of brake power to maximum extractable power) of the engine, which increased with engine load, was found to vary from 22 to 50 percent. It was concluded that besides heat transfer, the combustion process was the most important source of irreversibility and accounted for 25 to 43 percent of the lost power.