Simulation And Waste Heat Recovery Analysis On Engine Fuelled With Biodiesel

Currently, developing and applying new technologies of alternate energy sources and comprehensive utilization of energy is becoming the focus of concern in research field.The prospect of biodiesel research and application on small size power unit, along with the development of miniature comprehensive energy supply system were summarized in this paper, and the objective and significance of the study was clarified as well. Besides, the characteristic of Modelica, a programming language, and Dymola, a Modelica based software, as well as the related overview of research were introduced. A ZS195 diesel engine model and a model for analyzing waste heat recovery were set up based on Dymola.By compared the simulation result with test data, it was indicated that the simulation to engine power, fuel consumption and exhaust temperature were matched well with that of experimental result. The engine model can not only validate for diesel simulation, but also suitable for the work on biodiesel. When fuelled with biodiesels, the specific fuel consumption was higher than that of diesel, while the exhaust temperature of the biodiesels at high engine loads were always lower compared to that of diesel. The simulation also revealed that fuel energy has directly impacts to engine performance, exhaust temperature, exhaust heat energy and coolant heat energy. At any engine speed and engine load, exhaust heat energy was about 1.5-2.1 times higher than that of coolant heat energy. Whilst at high load, the heat energy in exhaust and coolant corresponding to diesel were much than that of biodiesel. Affected by the heat energy distribution in coolant and exhaust, the simulation result of recyclable waste heat energy kept the same trend, in which the recyclable exhaust heat energy was similar to the engine power output. At minimum load, recyclable heat energy of exhaust and coolant were almost the same, and the proportion of the recyclable exhaust heat energy to the fuel energy dropped down apparently in accordance with the decreasing of engine load.Some conclusions were draw after compared the engine performance and CO2 emission under the condition of before and after waste heat recovery. When take no account of waste heat recovery, the maximum engine power efficiency fuelled with different fuels were about 33 to 35 percents. After waste heat recovery, the figure raised sharply to 82 to 83 percents, the lowest thermal efficiency also increased from less than 20 percents to about 60percent, increased by 1.3 to 2.6 times, and barely differences of total efficiency were found among the fuels. While the CO2 emission decrease by about 60 percents, and this figure even increased to 70 percents at the minimum load of 2000rpm, revealing a distinct effect of energy saving and emission reduction. The emission of CO2 fuelled with biodiesl decreased by 2 to 9 percents in compare with diesel before waste heat recovery, and the after, this advantage reduced to 1-2%...