Research On Biodiesel Production From Waste Frying Oil And Application In Diesel Engine

Biodiesel, as a green alternative fuel, can effectively solve the problem of the diesel shortage caused by the increasing ratio of diesel automobiles all over the world in the future. Vegetable oils or animal fats repeatedly used to fry food in the catering industry is not only an impact to food taste, but also might have the potential carcinogenic risk and influence health. In this paper, we selected waste frying oil (WFO) as the raw material of biodiesel, transformed WFO into biodiesel, applied researches on the two platforms of real machine test and diesel engine simulation calculation. The major objectives were experimental research of biodiesel production and refining, discussion about diesel engine performance operating with biodiesel blended, biodiesel engine model construction and application. The specific research work conclusions as follows:The conditions of production procedures from two kinds of WFO into biodiesel were optimized via response surface method (RSM) with rapeseed oil as the control. The optimum conversion, physical and chemical properties and fatty acid methyl esters (FAMEs) of three biodiesels were compared. The results show that the influence of each factor on the oil production in descending order was:catalyst dose>methanol/oil ratio>temperature. The interactions which have a notable impact on yield are catalyst dose and methanol/oil ratio, catalyst dose and temperature. The conversions of the two WFO were 87.75% and91.81%, slightly lower than rapeseed oil’s 92.55% under the optimum process conditions. FAMEs content in two WFO biodiesels were higher than 99%. Then, through GC-MS analysis, the contents and molecular structure of FAME in biodiesel production are similar to those of the ideal diesel substitute. The heating value was in the range of 38.5～39 MJ/kg.Different refining methods are compared and optimized to obtain optimal conditions for industrial production. The results show that the most suitable rinsing method for industrial application was rinsing with saturated NaCl solvent. By applying orthogonal design, the optimal conditions of rinsing with saturated NaCl solvent were:water temperature,50℃; rinsing times,6; water/oil volume ratio,1.5-2.The impacts of the biodiesel blended on a diesel engine (CA4113Z) performance and exhaust emissions was evaluated by comparing with 0# diesel fuel. The results showed that engine performance with diesel blended with 20% biodiesel (B20) rivaled 0# diesel. Diesel blended with biodiesel had little effect on the specific fuel consumption, thus the influence on fuel economy is limited, which, however, is not an impediment to the popularization and application of biodiesel. In part (40%-80%) speed characteristic and low speed (1600 r/min), medium speed (2300 r/min), high speed (2600 r/min) load characteristic, smoke intensity and NOx emissions of diesel engine with B20 were significantly lower than 0#diesel. The B20 can be used in diesel engine without any modification and has a great potential future.Based on the GT-Power software, an engine cycle simulation for a biodiesel fueled engine was developed and typical physical properties of the biodiesel blended were measured. The effects of temperature using B20 on four cylinder diesel engine performances were researched and analyzed. The simulation results showed that the brake power and brake torque reduced 3.84% and 1.65% maximum respectively for the engine operating under different temperatures. The decrease in the lower heating value caused an increase in the brake specific fuel consumption thus reduces the brake thermal efficiency of engine performance at full load.