deNOx Mechanism Caused by Thermal Cracking Hydrocarbons in Stratified Rich Zone during Diesel Combustion(Diesel Engines, Performance and Emissions, NOx Strategies)

DOI Web Site

抄録

This study investigated deNO_X mechanism caused by thermal cracking hydrocarbons during diesel combustion experimentally and theoretically. Experiment using a rapid compression machine and a total gas-sampling device shows that NO_X can be reduced during second half of diffusion combustion under rich and high swirl condition. Under this condition, stratified rich region is distributed in the combustion chamber. Thermal cracking hydrocarbons are locally accumulated in this region. Moreover, it is shown that a large amount of thermal cracking hydrocarbons are produced during ignition delay period and at initial combustion stage. These hydrocarbons mainly consist of unsaturated hydrocarbon such as C_2H_4. At diffusion combustion stage, CH_4 becomes main hydrocarbon. A flow reactor system was used to investigate thermal cracking process of diesel fuel and NO_X reduction process. It is found that about 60% NO_X can be reduced under rich and high temperature condition. The condition is at equivalence ratio of over 2.5 and temperature of 1500K in this study. When C_2H_4 is introduced as fuel, NO_X can be further reduced up to 80%. It is indicated that C_2H_4 plays an important role in NO_X reduction. Chemical kinetic calculation using CHEMKINHI reveals the deNO_X mechanism. C_2H_4 is easily decomposed as compared with CH_4. During the oxidation process of C_2H_4, NO_X is reduced through the reaction of HCCO or CH_2 with NO. In this reaction path C_2H_2 is an essential species to form HCCO and CH_2. C_2H_2 is one of thermal cracking hydrocarbons and also formed through thermal cracking process of C_2H_4.

収録刊行物

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ