New regulations applied to the transportation sector are widening the operation range where the pollutant emissions are evaluated. Besides ambient temperature, the driving altitude is also considered to reduce the gap between regulated and real-life emissions. The altitude effect on the engine performance is usually overcome by acting on the turbocharger control. The traditional strategy assumes to keep (or even to increase) the boost pressure, that is, compressor pressure ratio increase, as the altitude is increased to offset the ambient density reduction, followed by the reduction of the exhaust gas recirculation to reach the targeted engine torque. However, this is done at the expense of an increase on fuel consumption and emissions. This work remarks experimentally the importance of a detailed understanding of the effects of the boost pressure and low-pressure exhaust gas recirculation (LP-EGR) settings when the engine runs low partial loads at different altitudes, accounting for extreme warm and cold ambient temperatures. The experimental results allow defining and justifying clear guidelines for an optimal engine calibration. Opposite to traditional strategies, a proper calibration of the boost pressure and LP-EGR enables reductions in specific fuel consumption along with the gas temperature increase at the exhaust aftertreatment system.

适用于交通运输部门的新法规正在扩大评估污染物排放的操作范围。除了环境温度外，驾驶海拔高度也被认为可以缩小管制排放与现实排放之间的差距。通常通过作用于涡轮增压器控制来克服海拔对发动机性能的影响。传统策略假设保持（甚至增加）增压压力，即压缩机压力比增加，随着高度的增加以抵消环境密度的降低，然后减少废气再循环以达到目标发动机扭矩。然而，这是以增加燃料消耗和排放为代价的。这项工作通过实验说明了详细了解增压压力和低压废气再循环 (LP-EGR) 设置影响的重要性，当发动机在不同高度运行低部分负载时，考虑到极端温暖和寒冷的环境温度。实验结果允许定义和证明最​​佳发动机校准的明确指南。与传统策略相反，适当校准增压压力和 LP-EGR 可以降低特定燃料消耗以及排气后处理系统的气体温度升高。实验结果允许定义和证明最​​佳发动机校准的明确指南。与传统策略相反，适当校准增压压力和 LP-EGR 可以降低特定燃料消耗以及排气后处理系统的气体温度升高。实验结果允许定义和证明最​​佳发动机校准的明确指南。与传统策略相反，适当校准增压压力和 LP-EGR 可以降低特定燃料消耗以及排气后处理系统的气体温度升高。