Experimental Study On Hydrogen Blend Ratio For HCNG Engine

As one of the solution for petrolic oil crisis and environment protection, hydrogen blend natural gas (HCNG) also act as feasible way to transform vehicle fule from Conventional fuel to hydrogen gas. This paper use EQD210N-20 natural gas (NG) engine made by Dongfeng as base engine.In theoretical part of paper, at first, equations were carried out for accouting the H2/NG blend ratio in mass or in energy on the H2 fractions in volumn. Secondly, the article calculates the combustion of using element potentials, and analyses the theoretical adidbatic flame temperatiur, properties of products in the equilibrium under different H2 blend ration and different coefficient of excessive air condition by program STANJAN. It can be seen that as the hydrogen fractions increased, the adidbatic temperature grow up, as the result the NO emission become higher. When Air/Fule ratio increasing, NO emission will decrease, it proved lean burn was available way to reduce NOx emission.In experiment part, firstly an on-board fueling supply system was build for the engine test after analyzing the configuration and accuracy of constant-pressure mixing system and on-board fueling supplying system. Then tests were carried out to determine the best blend hydrogen blend ratio, which include: emission test for unique rotate speed and constant power output, air/fuel characteristic test at different MAP one speed, equal torque test on full load, four mode equal fuel consumption emission tests. The tests result show that as hydrogen content increased, the NOx promoted at same coefficienct of excessive air because of higher temperature, but it can extend the lean burn limit. In lean burn condition, there is a trade-off relation between NOx and Hydrocarbon emissions, leaner combustion will cause Hydrocarbon emission increasing significantly, i.e.it need more exactly control for air/fuel ratio. It also discovered that retarding engine spark advanced angle for a large value only cause engine torque a small change, but as the result the NOx emission become lower.Finaly, a calibration were carried out on 20 vol% H2 content fuel, the result indicated the engine performance were maintained the same as for the natural gas fuel, while the NOx and NMHC were reduced.