| With the rapid development of automobile industry, energy consumption and environmental pollution of vehicles has become a worldwide problem. In order to effectively achieve the purpose of fuel economy and environmental protection, automobile technology is being promoted in the direction of energy conservation and diversification. Thus, to study start condition with the aim of fuel-saving and environmental protection becomes an important issue.This paper focuses on the basic thermal state of engine start condition in additional heat source cooling system. The impact of external heat source on engine start and warm-up process is studied by using electric heaters to heat cooling water. The author designs and tests four basic projects (original, synchronous heating, preheating, warm engine) and two combined projects (preheating. combined with synchronous heating, warm engine combined with synchronous heating). By adjusting the heating mode, heating power, preheating time, warm engine temperature and other parameters, the impact of each project on cooling water, oil, exhaust temperature and speed changes are analyzed. One-dimensional simulation software is also introduced to establish engine cooling systems and analyze the temperature rise process of cooling water in low temperature, variable flow condition and variable cooling water volume condition.Experimental result showed that each basic project improved the establishment of cooling water temperature and oil temperature in start condition to different extent. Great heating power, long preheating time and high warm engine temperature enhanced the improvement. Combined projects optimized each basic project itself in improving start performance and reduced energy consumption. Simulation result was consistent with the experimental result. It showed the temperature rise process of cooling water in variable flow and volume boundary condition, which had a certain significance in how to improve engine start and warm-up process. |
