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A neat, alkali-refined sunflower oil, a 50/50 blend (v/v) of sunflower oil and #2 diesel fuel, and 100% #2 diesel fuel were evaluated in a direct injected, one-cylinder Petter engine according to the SAE 13 mode test procedure. The experiment was conducted to evaluate the effects of plant oil based alternative fuels on exhaust emissions and to simultaneously compare the test fuels. Additionally, the effect of engine load and speed on the exhaust emissions using the plant oil alternative fuels was statistically evaluated. The response variables were CO, NO, HC, and smoke. The predictor variables were the concentration of sunflower oil in the test fuel, the engine speed, and load. A multivariate test and covariance analysis were used for the results evaluation.

This paper presents the evaluation results from the analysis of different blends of fuels using the 13-mode standard SAE testing method. Six high oleic safflower oil blends, six ester blends, six high oleic sunflower oil blends, and six sunflower oil blends were used in this portion of the investigation. Additionally, the results from the repeated 13-mode tests for all the 25/75% mixtures with a complete diesel fuel test before and after each alternative fuel are presented.

A 25-75 blend (v/v) of alkali-refined sunflower oil and diesel fuel, a 25-75 blend (v/v) of high oleic safflower oil and diesel fuel, a non-ionic sunflower oil-aqueous ethanol micro-emulsion, and a methyl ester of sunflower oil were evaluated as fuels in a direct injected, turbocharged, intercooled, 4-cylinder Allis-Chalmers diesel engine during a 200-hour ERA cycle laboratory screening endurance test. Engine performance on Phillips 2-D reference fuel served as baseline for the experimental fuels. This paper deals with several aspects of the anomalous behavior of the fuel injection system and its effects on long-term engine performance as experienced during the operation with the alternate fuels. Particular attention was paid to the changes in injection timing and the rates of injection pressure. Furthermore, secondary injection phenomena, initial and final stages of the fuel injection, which have been recognized as very frequent causes of abnormal combustion behavior, were analyzed.

The multivariate statistical procedure has been used to compare various alternate fuels based on the long term engine performance. The results from the multivariate analysis of covariance procedure, which does the simultaneous comparison of the chosen response variables, were adjusted for time of engine operation since the time factor was found to be significant. The assumptions for this test procedure are presented. Problems which could affect the validity of the statistical procedures for the laboratory endurance test are discussed. To illustrate the statistical method, data from a laboratory screening endurance test was used. Results of the analysis were in close agreement with the engineering interpretation of the observed differences between fuels.

Multivariate statistical procedure has been used to compare various alternate fuels based on the residue formation on selected engine parts. The results from the Multivariate Analysis of Variance procedure which does the simultaneous comparison of the chosen response variables are presented. The assumptions for this test procedure are given. Problems which could affect the validity of the statistical procedures for the endurance test are discussed. Data from a 200-hour EHA laboratory screening endurance test is used to illustrate the statistical methods. Results from the statistical analysis of the experimental data were in close agreement with the engineering interpretation of the observed differences between fuels. Critical engineering interpretation of the statistical results is still required due to the high sensitivity of the statistical analysis.