Hydrogen as an Auxiliary Fuel in Compression-Ignition Engines

An investigation was made to determine whether a sufficient amount of hydrogen could be efficiently burned in a compression-ignition engine to compensate for the increase of lift of an airship due to the consumption of the fuel oil. The performance of a single-cylinder four-stroke-cycle compression-ignition engine operating on fuel oil alone was compared with its performance when various quantities of hydrogen were inducted with the inlet air. Engine-performance data, indicator cards, and exhaust-gas samples were obtained for each change in engine-operating condition.

Hydrogen could be burned satisfactorily at all loads up to and including cruising at compression ratios of 13.4 and 15.6 in sufficient quantities to compensate for the increase in lift due to the consumption of the fuel oil. In the cruising range the mixtures of fuel oil and hydrogen burned as efficiently as the fuel oil alone. At small power outputs, the mixture of fuel oil and hydrogen burned less efficiently than the fuel oil alone; whereas, for power outputs greater than that required for cruising, the mixture of fuel oil and hydrogen burned more efficiently than the fuel oil alone.

For all loads except idling there was present in the exhaust water vapor weighing more than the fuel oil burned, approximately 25 percent more for all loads above cruising. When burning the maximum usable amount of hydrogen along with the fuel oil, the weight of water vapor was 80 percent more at full load and 200 percent more at small loads.

The engine always stopped firing when the fuel oil was cut off. Throughout the limits of the test conditions, it was never possible to auto-ignite the various mixture of hydrogen and air but the injection of even a minute quantity of fuel oil would cause the mixtures to burn. The engine showed no ill effects from the use of hydrogen and no change in engine operation was apparent.