Energy efficiency of engine-generator set using biofuels under varied loads

The experiment was conducted at the Experimental Center in Agricultural Engineering (NEEA), at the State University of West Paraná (UNIOESTE), Cascavel - Paraná, with a totally randomized experimental design. Treatments used were petroleum diesel and three different types of biodiesel: crambe (Crambe abyssinica Hochst), soybean (Glycine (L.) Merrill) and waste frying oil. The biodiesel was used in its pure form (B100) and in binary mixtures B10, B20 and B50. Resistive loads of 1, 2, 3, 4, and 5 kW were used for each type of fuel, with a total of five replications. Specific consumption (SC) and energy efficiency (EE) were evaluated. The best SC levels were achieved with diesel, with 349 g kW h−1 under the load of 5 kW, followed by CB20-2, with 524 g kW h−1 and CB50-3, with 433 g kW h−1. Biodiesel presented SC values close to those of diesel as resistive loads were increased, what indicates that its use in operations closer to the nominal capacity is more efficient. Among the biodiesel forms used, the crambe oil-based biodiesel presented lower SC and some of the values did not present significant differences (Tukey 5%) from diesel's SC, such as CB20-4, with 383 g kW h−1 and CB10-5, with 367 g kW h−1. The best energy efficiency values were found with DI-5 (25.6%), CB-100-5 (25.5%), CB50-5 (25.0%), SB100-5 (24.8%) and WFOB100-5 (24.6%). Pure biodiesel (B100) tends to present better EE than the mixtures used in the study. CB100 presented EE of 9.9%, 17.8%, 21.8%, 24.3% and 25.5%, according to resistive loads of 1, 2, 3, 4, and 5 kW, respectively. Regarding the biofuels assessed, crambe oil-based biodiesel presented the EE values that were closer to those of diesel. The energy efficiency of CB100 was higher than diesel's with loads of 2, 3 and 4 kW.