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Sheng X.,Jiangsu Nushen Automobile Group | Huang J.,Xian Jiaotong University | Wang X.,Xian Jiaotong University | Wang H.,Xian Jiaotong University | And 2 more authors.
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2013

Dimethyl ether (DME) can be used as alternative fuel of diesel. DME contains high oxygen and is smoke free, which creates an easy way for the off-road vehicles and low speed trucks to meet China IV and V Standard whose engines equipped with the conventional mechanical fuel injection system. In this paper, a 2102QB diesel engine was retrofitted to run on DME by enlarging its plunge diameter and nozzle flow area to increase cyclic DME fuel quantity. The effects of exhaust gas recirculation (EGR) on the DME engine power, fuel economy, and emissions were investigated, as well as the optimization of DME fuel delivery advance angle. The results indicate that EGR has minor effects on DME engine performances. Even under stoichiometric air fuel ratio condition, the DME engine power and fuel economy are less deteriorated, while NOx emission is reduced significantly. Based on the experimental data, the specific NOx emission was calculated and then it was used to set the rate of EGR under the ESC13 operating conditions. At the mean time, HC and CO emission were evaluated. DME engine gives out a little more HC, while CO increases to two or three times when the DME engine NOx emission meets the regulations of China 4 and 5. The investigation proved DME engine clean combustion theory and provided a way to achieve low emissions of DME engines.

Sheng X.,Jiangsu Nushen Automobile Group | Gao G.,Xian Jiaotong University | Wu G.,Xian Jiaotong University | Liu S.,Xian Jiaotong University
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2012

A 2102QB CI engine fueled with DME (dimethyl ether) was adopted to investigate the injection process and influencing factors. The pressures at the pump end and the nozzle end of the injection pipe were measured at different engine speeds, loads and DME fuel temperatures. The injection delay, duration and sound speed were calculated by combining the signal of the needle valve lift. The experimental results indicate that DME has a lower bulk modulus, which reduces the pressure wave propagation and causes a longer injection delay and duration. The temperature of DME has a significant effect on the injection process. Higher temperature leads to smaller peak injection pressure, longer injection delay and duration. The fuel delivery advance angle of the DME engine should be optimized according to engine speed and fuel temperature.

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