A comparative experimental study on emission characteristics and ammonia energy ratio of diesel generator operating in ammonia/diesel dual fuel mode by premixed and port injection

Abstract

The extensive use of traditional fossil fuels has exacerbated crises such as environmental pollution, depletion of non renewable energy and global greenhouse effect. Ammonia (NH3) is considered a promising fuel to replace conventional fossil energy in internal combustion engines. A four-cylinder, four-stroke commercial diesel generator (HTD-20GF) was modified and two different ammonia fuel injection systems, premixed charge compression ignition (PCCI) combustion and gas phase port injection (GPPI), were developed. The exhaust emission characteristics, thermal efficiency and ammonia energy ratio of ammonia/diesel dual fuel (ADDF) generator in both PCCI and GPPI modes were studied. The experimental results showed that the overall NO emission in GPPI mode was lower than that in PCCI mode. From the experimental results, both PCCI and GPPI mode can reduce CO2 emission. The GPPI mode was significantly more effective than the PCCI mode in reducing the volume fraction of CO2 in the exhaust gas. Compared with all diesel mode, the HC content in the exhaust gas got worse at lower ammonia energy ratio in both modes, but the increase rate of HC emissions slightly improved as the ammonia energy ratio increased. However, PCCI and GPPI modes reduced the thermal efficiency of the generator, and ammonia had a more negative effect on the thermal efficiency of the ADDF generator in PCCI mode.The experimental results also tested the limiting ammonia energy ratio of this commercial generator at 1 kW. In summary, this study provides a new perspective on the different feeding methods of ammonia as a fuel, which may contribute to the selection of fuel injection methods for ammonia engines to decrease emissions.