Feasibility study of a scroll expander for recycling low-pressure exhaust gas energy from a vehicle gasoline engine system

The growing number of vehicles on the road has led to a rapid increase in fuel consumption and toxic gas emissions, so the challenges in fuel efficiency improvement and reduction of CO2 and NOx emissions have always been on the top agenda of the automotive industry. The paper presents a feasibility study of recovering the low-pressure exhaust gas energy via by-pass connection of a scroll expander to the engine system exhaust. The paper starts with the description of the proposed new exhaust energy recycling scheme and the mathematical modelling of the system. A feasibility study is carried out to investigate whether this new scheme can work with the engine operation conditions specified by the engine test data. The initial study indicated that the scroll expander structure needs to be modified; otherwise, it cannot be used for exhaust energy recovery. The experimental test and simulation results presented in this paper indicate that it is feasible to recover the low-pressure exhaust gas energy using a scroll expander with a modified structure. The proposed energy recovery system has the potential to produce over 400 W power output with over 90% of engine exhaust flow recycling

Predictive control of the engine cooling system for fuel efficiency improvement

The engine cooling system in trucks is one of the main sources of parasite load. Thus fuel efficiency can be improved by optimal control of engine thermal management system considering fuel consumption minimization as the objective. Although several optimal control methods have been proposed for the engine cooling system, their main emphasize is on regulating engine and coolant temperature in an acceptable range rather than minimizing fuel consumption. In contrast, this paper investigates the fuel saving potential of predictive optimal control methods for the engine cooling system of conventional trucks. Our method exploits the idea of energy buffers in the automotive system, where the engine cooling system and the battery serve as energy buffers. The advantages of this approach are the recovery of brake energy and the balance of energy sources so that the total energy loss is minimized. A model predictive controller is used as the real time controller, and the results are compared with a simple state feedback controller and a global optimal solution obtained by dynamic programming. The results show limited but notable improvement in fuel efficiency. The results also construct a base for ongoing research on energy buffer control in conventional heavy trucks.QC 20150716</p