Numerical Simulation And Idle Characteristics Experiment Of Hydrogen-enriched HCNG Engine

Coke oven gas (COG) resources are abundant in reserve but with low utilizationrate in China. COG has broad prospects for development as a fuel for vehicleapplication after purification because it’s rich in hydrogen. Hydrogen enrichedcompressed natural gas (HCNG) is a new type fuel for ground vehicle applicationswhich can be achieved by blending natural gas with hydrogen. HCNG is served as afeasible approach to fasten the transition from traditional vehicles to vehicles poweredby hydrogen.The main work of this thesis can be divided into two parts. One is to focus on theperformance simulation of the hydrogen-enriched HCNG engine based on the softwareof AVL BOOST. Another is to research the idle characteristics of thehydrogen-enriched HCNG engine through experimental methods.In the numerical simulation study, a full model of the hydrogen-enriched HCNGengine was built up. The truncational model with high precision was then built basedon the experimental results. The truncational model was applied to various parametricstudies, including compression ratio（ε） and valve timing. The results show that,(1)the increasing in compression ratio can improve the power and fuel economy of theengine within a certain range.(2) The power and fuel economy of the engine arereduced because of the decreasing of valve overlap.(3) Compared to the original CNGengine, the power and brake specific fuel consumption(be) of hydrogen-enrichedHCNG engine decrease slightly at conditions of improving compression ratio from10:1to12:1and reducing the valve overlap from30°CA to0°CA at the same time.In the experimental part, two factors including ignition advance angle（θig） andexcess air ratio (φa) were involved to research the idle characteristics of thehydrogen-enriched HCNG engine. Reducing the idle speed of an SI CNG enginefueled with hydrogen-enriched HCNG was also studied as an important part in thisthesis. The test results show that,(1) compared with the original CNG engine, theindicated thermal efficiency (ITE) of the hydrogen-enriched HCNG engine issignificantly improved. And the equivalent fuel consumption can be reduced at thesame time.(2) For the hydrogen-enriched HCNG engine, the CoVimepis still lowerthan3%while theφais increased from1to1.2. So lean-burn technology can be usedto improve the fuel economy of the engine.(3) The hydrogen-enriched HCNG engine has low CO, CH4, and THC emission while the NOXemission is higher. But NOXemission can be reduced through increasing excess air ratio.(4) In order to improve theITE, reduce fuel consumption and emissions (CO, THC, and NOx) of thehydrogen-enriched HCNG engine at idle condition, the idle speed is reduced and theexcess air ratio must be increased appropriately at the same time.