内燃机能量流试验是评估不同控制策略下内燃机能耗和指明其改善方向的重要方法。通过试验对1台涡轮增压缸内直喷汽油机进行了基于冷却液温度的能量平衡分析,基于热力学定律，将能量平衡项分为有效功、冷却液损失、排气损失和通过辐射传热产生的未计入热损失。结果表明：小负荷时，随着冷却液温度的升高,燃油消耗率略有下降，NO_x 排放量增加；全工况下，HC排放量随着冷却液温度的升高而减少，CO和CO₂排放量变化不大；有效功占比和排气损失占比随负荷的增大而增大，几乎不受冷却液温度的影响；冷却液损失占比随冷却液温度的升高而减小。

Energy flow test of internal combustion engines is an important method to evaluate energy consumption of engine under different control strategies and indicate improvement directions. The energy balance analysis based on coolant temperature was carried out on a turbocharged direct injection gasoline engine. According to the thermodynamics law, the energy balance terms consisted of useful work, cooling loss, exhaust loss and unaccounted heat loss caused by radiative heat transfer. The results show that the specific fuel consumption decreases and NO_x emission increases at low load; while HC emission decreases and CO and CO₂ emissions keep almost the same at whole working conditions with the increase of coolant temperature. The ratios of useful work and exhaust loss increase with the increase of load and are little influenced by coolant temperature. In addition, the cooling loss ratio decreases with the increase of coolant temperature.