Energy and exergy analysis on gasoline engine based on mapping characteristics experiment

In order to evaluate the energy utilization efficiency of gasoline engine and predict the recovery potential for waste heat energy, energy distribution and waste heat energy characteristics of a naturally aspirated gasoline engine have been studied by combining the methods of energy and exergy analysis. During the research processes, engine energy balance tests were conducted under mapping characteristics, and the parameters required for calculating the energy balance and exergy balance were measured. On this basis, waste heat recovery potential and gasoline engine total exergy efficiency were studied by using the method of exergy analysis. Research results show: at low-speed and low-load, waste heat energy mainly focuses on cooling water; at high-speed and high-load, exhaust gas energy is larger than cooling water energy not only in quantity, but also in exergy percentage and exergy efficiency; the highest exhaust gas exergy efficiency appears in high-speed and high-load area, while the highest cooling water exergy efficiency appears in low-speed and low-load area; theoretically, total fuel efficiency of this gasoline engine can be nearly improved by a time through waste heat recovery, and the maximum total fuel efficiency can reach 60%.