Experimental Research on the Matching Characteristics of the Compound VGT-STC System with a V-Type Diesel Engine

Abstract

In order to improve the performance of a V-type diesel engine at low and medium speeds, the compound VGT-STC turbocharger system was proposed. First, the compound VGT-STC turbocharger system bench was established, which allowed to switch between the VGT and STC boosting systems. Then, the load characteristic tests with a variable VGT vane opening were conducted at different speeds in the 1TC and the 2TC, respectively. The results showed that the VGT-1TC could provide much more air into the cylinder than the VGT-2TC at 1000 r/min, and the maximum torque was increased by 4000 Nm (80%), and the BSFC decreased by 20.1 g/kWh on average. The matching characteristics are analyzed for three boosting control strategy systems, including the VGT, STC, and the compound VGT-STC. The results show that the VGT system has a steady increase of the maximum torque in both low and medium speeds, while the STC system has a large increase in torque at 1000 r/min and begins to decline when speed is greater than 1200 r/min, and the compound VGT-STC system combines the advantages of the VGT and STC, which can maintain 9000 Nm (83% rated torque at 1800 rpm) and a lower BSFC at both low and medium speeds. As a result, with the compound VGT-STC boosting control strategy system, the operating range has expanded by 10%, and its smoke opacity, BSFC, and exhaust temperature are reduced by 0.057, 8.2 g/kWh, and 64 °C, respectively.

A New Generation of Hydrogen-Fueled Hybrid Propulsion Systems for the Urban Mobility of the Future

“…In Figure 15 (left), the efficiency is plotted as a function of the exhaust mass flow rate mexh: the values range from 55% to 68%, and The first result is the pressure ratio of the turbocompound βTC, which is related to the pressure admissible on the exhaust line since the outlet pressure is close to the environmental one. The growth in turbocompound pressure ratio increases the engine backpressure, although the presence of a Variable Geometry Turbocharger (VGT) mitigates this value on the exhaust manifold of the engine [58,59] and it is considered in the net power estimation (PTC, net). Figure 14 shows the turbocompound pressure ratio, which is linearly dependent on the exhaust temperature Texh (i.e., turbocompound inlet temperature) and ranges from 1.2 to 1.6.…”

Study on Through-Flow Characteristics of a Diesel Two-Stage Supercharged Centrifugal Compressor under Variable-Altitude and Multiple Operating Conditions

“…VGT + VGT can integrate the advantages of the TST and the single-VGT system and represents the development trend of the two-stage supercharging system for vehicles in the future [10]. Compared with the single-stage turbocharger, the dual-VGT two-stage adjustable turbocharger system realizes the effective distribution of exhaust energy in the high-and low-pressure-stage turbines by adjusting the blade opening of the high-and low-pressure-stage VGT, which indirectly controls the speed of the turbocharger, and realizes the precise control of the booster pressure and intake flow to improve the comprehensive efficiency of the turbocharger system [11]. Although two-stage turbocharging and variable-section turbines can meet the measures of variable altitude by improving the utilization rate of exhaust energy at the turbine end, the improvement range and potential of the compressor end are constrained by the single-point matching condition, and the mismatch between the environmental factors and the turbocharger leads to the poor adaptability of the compressor at high altitudes [12].…”