Evaluation of polyoxymethylene dimethyl ethers as a new type of diesel additives

Polyoxymethylene dimethyl ethers (PODEn) is an emerging biofuel that has a great potential to become one of the competitive alternative fuels for diesel engine. In the present study, systematic studies were made to evaluate the influences of PODEn on the physical fuel properties that are routinely used to define the quality of diesel fuels. Such fuel properties were measured for the three (diesel + PODEn) mixtures, diesels, and PODEn. The measured properties included cetane number, lubricity, density, viscosity, solidifying point, cold filter plugging point, flash point, and heat capacity. Comparisons of measured properties of the mixtures and their individual components were made to achieve the following purposes: First, to reveal the changes in the properties of diesels upon the addition of PODEn and in the properties of the (diesel + PODEn) mixtures as the weight percent of PODEn is increased; Second, to see whether or not the addition of PODEn worsens the properties of diesels, in particular, whether or not the measured values of the (diesel + PODEn) mixtures exceed the standard values set by the Beijing-VI. Novel theoretical equations were developed to quantitatively predict the density, viscosity, and heat capacity of the (diesel + PODEn) mixtures in terms of the corresponding properties of the diesel and PODEn. Comparisons were made between measured and predicted properties and the agreements are excellent.