Effect of polyoxymethylene dimethyl ethers addition on spray and atomization characteristics using a common rail diesel injection system

- The effect of PODE addition on the spray characteristics is observed.
- Nozzles with different diameters were employed in this work.
- The experimental results on spray tip penetration were compared with empirical equations.
- The macroscopic and microscopic spray characteristics were investigated.

PODE is named for the mixture of polyoxymethylene dimethyl ethers. Recently, it is used as diesel oxygen additive to reduce diesel engine smoke. In this study, the effect of PODE addition on the spray and atomization of diesel spray was investigated by using a high pressure common rail system. The spray tip penetration (STP), the spray cone angle and the spray projected area were extracted at the injection pressure of 60, 90 and 120 MPa and the ambient pressure of 4 MPa through a high speed photographic device. The results show that as PODE is added into diesel, the STP is slightly decreased and the average spray cone angle and projected area are slightly increased. In addition, the microscopic spray characteristics such as statistical droplets size distribution and characteristic diameters and relative size range were obtained by a particle/droplet image analysis (PDIA) technique. The results shows that as PODE is added into diesel, the droplets number tends to be uniformly distributed around 12-20 μm range and smaller characteristic diameters are observed and the relative size range keeps constant. All of such characteristics of the spray indicate that PODE addition can better the atomization of diesel spray.