Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2010
Publication Date: April 30, 2010
Citation: Dunn, R.O. 2010. Cold Flow Properties of Biodiesel by Automatic and Manual Analysis Methods. Journal of ASTM International. 7(4):1-15. Interpretive Summary: This research demonstrated that cold flow properties of biodiesel and its blends in petrodiesel may be monitored accurately and at lower cost by automatic analysis. Accurate analysis of cold flow properties is crucial to the commercial viability of biodiesel during cooler months in moderate temperature climates. These properties depend mainly on the chemical composition of the parent oil before it is converted to biodiesel. This is important as less expensive feedstocks including waste greases, used cooking oils, vegetable oil refining wastes (soapstock), field pennycress and other low-maintenance plants and microalgal oils are developed for conversion to biodiesel. The present study analyzes three important properties pertaining to cold flow performance of biodiesel made from soybean oil, sunflowerseed oil, tallow, used cooking oil and high-acid acid oil (made from soapstock). Cold flow property data was obtained more rapidly and accurately from automated methods than from industry standard manually-operated equipment and methods. Results from this study will be employed to support fuel producers, distributors and terminal operators in efforts to improve the flow behavior of biodiesel during cold weather. Results will also directly benefit scientists and engineers in developing technologies to improve the cold flow performance of biodiesel.
Technical Abstract: Biodiesel from most common feedstocks has inferior cold flow properties compared to conventional diesel fuel. Blends with as little as 10 vol% biodiesel content typically have significantly higher cloud point (CP), pour point (PP) and cold filter plugging point (CFPP) than No. 2 grade diesel fuel (DF2). Although PP and CFPP may be lowered by treating with cold flow improver additives, these additives do not reduce CP by more than 3 to 5 deg C. When stored in moderate temperature climates, biodiesel should be periodically monitored during cooler months. This work examines the use of automated ASTM test methods to reliably monitor CP, PP and CFPP. Automated instruments have a number of advantages over manually operated apparatus, namely small sample volumes, consistency, speed of analysis and accuracy of results. Some deviations in data from automated and manual techniques were observed across a diverse set of biodiesel samples. Biodiesel samples were analyzed by sub-ambient differential scanning calorimetry (DSC) performed at various heating and cooling scan rates for comparison with cold flow property results.