Olika alternativa bränslens antändningsegenskaper mot het yta

In the Nordic countries, alternative and renewable fuels have steadily been gaining popularity during the last decades. This since alternative fuels reduce both the dependence on fossil fuels and the emission of greenhouse gases that affects our atmosphere. These are important advantages but the alternative fuels can also have a negative impact on the fire safety due to their different physical and chemical properties when compared to conventional fossil fuels. This means that alternative fuels can be more ignitable when they enter into contact with hot surfaces, as compared to conventional fossil fuels. Information about different fuels’ flashpoint and auto ignition temperatures can easily be found on different fuel companies’ websites. Though, the safety data sheets do not have any information about hot surface ignition temperature of the fuels. Therefore it is important to study the ignition probability of fuels when entering into contact with hot surfaces to assessing the risk for fires in vehicles. The main aim of this study is to investigate the ignition probability of a number of alternative fuels when entering into contact with a hot surface. Another aim is to study if the droplet size has an influence on the ignition temperature. The objective in this study is to perform an experiment about hot surface ignition at SP Technical Research Institute of Sweden, in Borås. The experiment setup was built after reading different articles and reports that were investigating hot surface ignition with different experimental setups. More than 4200 ignition tests were conducted during the experimental phase of this study. The fuels were chosen by reading statistics about what alternative fuels that currently are the most common ones in Sweden.The results shows that even if the fuels have almost the same boiling point, auto ignition temperature and flash point the surface temperature needed for ignition does not need to be the same. A trend indicated that the droplet size may have an impact on the ignition temperature. With a bigger droplet size the ignition temperature became lower and with a smaller droplet size the ignition temperature became higher. Mixtures of Diesel with alternative fuels will generally decrease the surface temperature needed to achieve ignition compared to pure Diesel. The statistical approach for the test method is important to get reliable results. Hot surface ignition is a complex phenomenon with many different factors such as the droplet size, the surface material and the local airflow. Therefore the hot surface ignition temperature is hard to use as a fuel property but it can be useful to assessing the risk for fires in vehicles. With a polished surface of stainless steel the results shows that Diesel MK1 have a 0 % ignition probability at 445 °C and a 100 % ignition probability at 555 °C. Corresponding temperature for pure RME is 340 °C and 470 °C, and for RME/Diesel 385 °C and 485 °C. The results for pure HVO and HVO/Diesel shows only at which surface temperature it started to achieve ignition. Pure HVO started to achieve ignition at 300 °C and HVO/Diesel at 310 °C.Validerat; 20160122 (global_studentproject_submitter