Instantaneous Energy Balance and Performance Analysis During Warm Up Period of a Spark Ignition Engine Under Several Thermal Energy Management Strategies

Abstract

Significant improvements can be obtained through different thermal energy management systems (TEMS) in internal combustion engines during warm up period. When the engine thermal energy management system works correctly, it ensures that the engine components are cooled exactly as needed, which is important in energy consumption and harmful exhaust emissions production. Additionally, thanks to the reduced warm up time, friction losses are reduced, after-treatment performance is increased, comfort conditions are improved in the passenger compartment, and the windshield quickly clears ice and condensation. However, the effects of the designed engine TEMSs on the energy balance during the warm up period should be well known. For this purpose, an experimental setup was established for not only the averages of the effects of different thermal strategies established as commonly done in the literature, but also the changes during the whole warm up process were analyzed. Then, three different TEMS were compared, and the effects of energy losses on each other were revealed. Results have shown that the warm up time can be reduced by 30 % with different engine TEMS, and thus, specific fuel consumption and CO emission can be reduced at different levels under several engine operating conditions. It was observed that when the engine coolant was not sent to the oil cooler heat exchanger during the warm up period, the thermostat opening time decreased from 252 s to 218 s. Moreover, it has been observed that the engine can reach steady state operating conditions approximately 10 % faster when the thermal energy is transferred from the exhaust gases, where a significant part of the fuel energy is lost, to the cooling water during the warm-up period.