{'fraction_non_alphanumeric': 0.022307202039515615, 'fraction_numerical': 0.0057361376673040155, 'mean_word_length': 4.902255639097745, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
An Experimental Study on the Characteristics of Nitrogen Oxide Reduction according to Thermal Insulation of After-treatment System of Industrial Diesel Engines

It is a well-known fact that a urea-SCR system is a highly efficient after-treatment system for NOx reduction; however, it is advisable to reduce the time to reach the light-off temperature due to its sensitivities to the exhaust gas temperature. Therefore, an experimental study was conducted on the reduction of the time to reach the light-off temperature through the application of the thermal insulation on the after-treatment system and the resulting NOx reduction efficiency. The engine used in this study is a 74 kW diesel engine with a displacement of 3.8 liters, a common rail fuel injection system was applied, and the after-treatment system was composed of DOC, DPF, SCR and AOC. Every performance test was conducted on the non-road diesel engine's certification test mode, NRTC mode, and the identical after-treatment systems and engines were used on the test except for the application of insulation. As a result, through the application of insulation on the after-treatment system, the temperature rise time of the SCR catalyst was shortened which made it possible to reach the urea injection start point more quickly, and the NOx emission was reduced. In addition, the rise of the SCR catalyst temperature by the applied insulation made the reduction reaction by NH3 adsorbed on the catalyst in the low-temperature section activated which led to an 10.54% increase of NOx reduction efficiency.