Experimental study on the engine energy flow of a heavy-duty vehicle under C-WTVC

To explore ways to improve the effective thermal efficiency and fuel economy of heavy-duty vehicles, the vehicle energy flow test was conducted under Chinese-World Transient Vehicle Cycle (C-WTVC). According to the data of the test, the distribution law of transient energy flow was analyzed. The results show that the energy flow distribution of the diesel-powered heavy-duty vehicle is mainly influenced by vehicle operating conditions. The percentages of effective power, exhaust energy flow, coolant energy flow, pump loss energy flow and other loss of the vehicle under C-WTVC are 35.7%, 35.08%, 19.64%, 2.05% and 7.52%, respectively. The variable range of various energy flow is particularly high due to the vehicle’s frequent acceleration and deceleration under C-WTVC. The phenomenon of ”oil break” will cause fuel energy flow, exhaust energy flow, and effective power to plummet to near zero during the sudden deceleration period. At this time, the percentage of pump loss energy flow and coolant energy flow will increase sharply. As a result, a reasonable fuel injection strategy during vehicle acceleration can effectively reduce the variation between cycles, thus improving the effective thermal efficiency and fuel economy. In addition, the waste heat loss of coolant and exhaust energy flow has a great utilization space. [Display omitted] •The heavy-duty vehicle energy flow test was carried out on a chassis dynamometer.•The influence mechanisms of various kinds of engine energy flow were revealed.•The average effective thermal efficiency of the heavy vehicle under C-WTVC was 35.7%.•Most of the energy loss was taken away by coolant and exhaust gas during deceleration.