The possibility of use a waste product of biofuels production-glycerol as a fuel to the compression ignition engine

The article presents results of tests performed in a combustion research unit (CRU) with the two following fuels: light fuel oil (LFO) and glycerol. The CRU is a constant volume combustion chamber machine equipped with an injection system based on that used in common-rail diesel engines with electromagnetic injectors. This machine allows to compare various combustion properties between fuels for specified parameters of injection and a combustion chamber as well. As it is known glycerol is a substance which is obtained from several technological processes such as production of biofuel thus in this way it can be treated as an alternative renewable fuel. The glycerol is characterized by low heating value of 16MJ/kg and relatively high density of 1261 kg/m3. However, its heating value by volume is higher if compared to other liquid fuels. From that reason decrease in energy that can be delivered with fuel is smaller which is approximately 16% lest than for LFO. The parameters measured during this research were: pressure increase, rate of pressure increase (ROPR), ignition delay (ID), main reaction delay (MRD), main combustion period (MCP), end of main combustion (EMC), end of combustion (EC), position of max ROPR (PMR) and max ROPR. The tests were performed with different injection parameters such as injection pressure, injection duration and injection delay as well as under various conditions in the CRU combustion chamber expressed by pressure and temperature. On the basis of these tests the comparison between LFO and glycerol was done. The results were presented in diagrams. The research shows that glycerol used as a fuel, to obtain the same output power, should be injected at higher amounts. Glycerol as a fuel cannot ignite itself, hence to provide combustion the pilot injection of another fuel have to be applied.