No abstract

A thermogravimetric analyzer (TGA) was used to oxidize real diesel soot produced in a modern four-cylinder, turbo-charged, diesel engine equipped with a common rail injection system. In the first part of the study, a large amount of soot produced with a variety of diesel fuels of current and future interest and in typical engine modes was collected. A thorough test matrix was designed and executed in the TGA to develop an optimized oxidation method, which allows for the determination of oxidation profiles, characteristic temperatures, and Arrhenius kinetic parameters. Such parameters are critical for modeling diesel filter regeneration and designing more efficient regeneration techniques. A comparison of this method to others proposed in previous literature is made, and the advantages are pointed out. In the second part, diesel and biodiesel soot produced in three engine operating modes (low, medium, and high load) was evaluated with the proposed method. The results showed that the effect of the fuel on the oxidation process was more significant than that of the engine mode. Biodiesel soot oxidation occurred at lower temperatures, proving the possibilities that this fuel offers for achieving more efficient filter regeneration. Although differences in the activation energy of diesel and biodiesel soot were not large, the oxidation rates of biodiesel soot were, on average, 1 order of magnitude above those of diesel soot.

Biodiesel from different mixtures of animal fat and soybean oil has been synthesized, and its properties have been evaluated and related to its composition. A mixture of 50 vol % of both raw materials has been selected as a suitable feedstock for industrial biodiesel production, and a computer simulation of the production process using Aspen Plus software has been carried out to evaluate the industrial feasibility of this scheme using this cheaper feedstock. The results obtained suggest that the process proposed and described produces a biodiesel with the selected feedstock acceptable by the standards with a lower final cost. The feedstocks employed are cheaper and consist of a waste fat without any other use, thus increasing the environmental benefits of the biodiesel and reducing dependency on conventional agricultural raw materials.

With the aim to evaluate the biodiesel performance and emissions of a feedstock with promising economic and sustainability perspectives, such as waste animal fat, two biodiesel fuels, one obtained from 100% animal fat and the other from 50% soybean oil/50% animal fat, were tested in a DI common-rail diesel engine. Blends [30 and 70% (v/v)] of these two biodiesel fuels with reference diesel fuel were also tested. The pressure drop across the fuel filter was measured, and for the pure animal fat biodiesel fuel, a large increase in pressure over 5 h was recorded, indicating a clogged filter. This poor filterability should be considered by biodiesel fuel manufacturers to decide about combinations of different feedstock or additivation. Brake thermal efficiency was not affected by the use of biodiesel fuels, for both pure and blended cases. A slight increase in fuel consumption was measured for all biodiesel fuels, and it was proportional to the heating value of the fuels. Biodiesel fuels reduced hydrocarbon emissions, smoke opacity, particulate matter, particle mean diameter, and total particle concentration, with the magnitude of these decreases depending upon the biodiesel fuel origin. NO x emissions were increased with the 50:50 animal fat and soybean oil compared to the reference diesel fuel but decreased with the pure animal fats, and combustion was advanced as the percentage of biodiesel fuel in the blend was increased.