Effectiveness of Cold Flow Additives on Various Biodiesels, Diesel, and Their Blends

Abstract

One of the major reasons hindering the use of biodiesel is its filter plugging temperature, which is higher than that of No. 2 diesel. Cloud point (CP) and pour point (PP) temperatures have been shown to be well correlated with filter plugging point, which primarily determines the operability of a diesel engine in cold weather. Many biodiesel cold flow additives are available in the market that claim to reduce pour point. In this study, neat and blended biodiesel fuels from different feedstocks were tested for change in CP and PP with various cold flow additives at 100%, 200%, and 300% of the specified loading (application) rate. The additives in general worked better for ethyl esters than for methyl esters. Average reductions in CP and PP for neat mustard methyl esters were 0.3C and 7.2C, respectively, compared to 3C and 19.4C for mustard ethyl ester at the recommended loading rate. In general, mustard biodiesel responded to additives better than soybean or used vegetable oil biodiesel for reducing PP. The effect of additives on CP of diesel fuel was not statistically significant, but PP was reduced to < -36C with all additives at recommended loading. This result is expected as additives are mainly targeted to inhibit the crystal growth not necessarily the onset of crystallization. The additives were found to be more effective in diesel than in biodiesel for reducing PP, and hence the higher the percentage of diesel in a blend, the better the effectiveness was. Most additives reduced the PP of B20 and lower blends to < -36C at 100% loading, and all additives did that at 200% loading. No added benefit was observed at more than 200% loading.