Use of waste fats of animal and vegetable origin for the production of biodiesel fuel: Quality, motor properties, and emissions of harmful components

One of the ways to reduce the price of biodiesel fuel is to use waste fats of animal and vegetable origin. The objective of this work was to investigate the physical and chemical properties of the fatty acid methyl esters of animal and vegetable origin and their mixtures, to determine their motor characteristics, to choose the optimal composition of biofuel mixtures, and to perform comparative analyses of emissions of harmful components in exhaust gases. It was determined that pure fatty acid methyl esters of animal origin and linseed oil fatty acid methyl esters do not meet standard requirements and cannot be used directly in diesel engines. For diesel engines, three-component mixtures of rapeseed oil methyl esters (RME), pork lard methyl esters (PME) or beef tallow methyl esters (TME), and linseed oil methyl esters (LME) (where the proportion of LME and methyl esters of animal origin is 1:4) may be used as fuel. According to the comparative analyses of motor characteristics of three-component mixtures, they are practically equal to the certified RME and its mixtures with fossil diesel fuel. If these three-component mixtures are used for the high-speed diesel engine, CO emissions are reduced by 20%-50%, hydrocarbon (HC) emissions are reduced by 50%-60%, and the smoke opacity of the exhaust gases is reduced by 25%-70%. The increase in NOx emissions does not exceed 13%; no significant changes in the CO2 emissions have been noticed. When the mixtures with fossil diesel fuel that contained 30% of the aforementioned three-component biofuel mixtures were tested, CO emissions were reduced by 15%-40%, HC emissions were reduced by 30%-45%, and the smoke opacity was reduced by 25%-30%. The NOx emissions increased similar to 6%; there were no notable changes in CO2 emissions.