重型柴油机低温起动及暖机过程的颗粒排放特性

The high soot particle emission during the start-up process of heavy diesel engine at low-temperature has a serious effect on the start-up efficiency. The start-up performance of diesel engine at low-temperature is influenced by the coolant and lubricating oil temperature. To reveal the soot particle emission characteristics of diesel engine during start-up process at low temperature, the in-cylinder pressures, and soot and particle emissions at different initial coolant and lubricating oil temperature conditions during start-up and warm-up are measured by single-cylinder engine bench test. The results show that the soot emission of the engine is the highest in the early stage of low-temperature start-up. With the increase of coolant and lubricating oil temperatures during warm-up, the soot emission gradually decreases, the number concentration of aggregated particles is reduced, the number concentration of nucleation mode particles is increased, and the total particle number concentration is dominated by nucleation mode particles. Increasing the initial coolant and lubricating oil temperatures under cold start-up condition reduces the soot emission during the start-up process, the number concentration, particle size, surface area and mass of nucleation mode particles decrease, the number concentration of aggregated particles decreases, and the particle surface area and mass are increased with the increase in large-sized aggregated particles. The soot and particle emissions during the start-up process can be reducedd by increasing the heating capacity of the heating pot at low temperature to increase the initial temperatures of coolant and lubricating oil, which improves the start-up efficiency and reduces environmental pollution.