(421bl) Excess Molar Volume and Energy Content of Biodiesel/Diesel Blends

Biodiesel has been popular for years as a first generation biofuel because of its comparable energy content, low sulfur, and reduced particulate emissions when compared to petroleum diesel.  Low-percentage blends of biodiesel and diesel fuel may be used in diesel engines without modification, and with few modifications, higher percentage blends as well as pure biodiesel may be used.  Significant changes in volume due to mixing may cause a decrease or increase in energy content of the fuel on a per volume basis.  The effect of blend percentage on fuel volume and energy content may become significant to both fuel producers and consumers as biodiesel becomes more widely used.  Blends of soybean biodiesel and ULSD were made (B5, B10, B20, B40, B60, B80, B90, B95).  The densities were measured and the excess molar volume for each mixture was calculated for temperatures between 283.15 and 363.15 K.  The change in volume due to mixing was found to be small, but measurable.  The energy content of these blends was found to be a highly-linear function of the biodiesel mass fraction.