Experimental investigation on the effect of diesel-biodiesel blends on waste heat recovery capability of a small power generator

In diesel engines, a significant part of extracted energy from fuel combustion is lost through exhaust and engine coolant system. The use of biofuels can also affect the heat recovery of the engine. According to the Results of a recent research, the quantity and quality of heat recovered by exhaust gas decreases by increasing the percentage of biodiesel in blend. In the mentioned study, only pure biodiesel fuel and a mixture of 50% biodiesel with conventional diesel have been investigated. While, it is usually recommended to use blends less than 20% biodiesel in standards. In this paper, the potentiality of waste heat recovery of a small power generator has been investigated for B10, B20 and B30 and compared with custom pure diesel fuel. For this purpose, a single module thermoelectric generator (TEG) was used. Results showed that the effect of biodiesel on the waste heat recovery potential of the engine has not a monotonic decreasing trend. As the biodiesel volume increases by up to 20%, the waste heat recovery potentiality increases. Further increasing of biodiesel fraction in blend will reduce the potential of heat recovery. The highest potential for heat recovery was found for blend of B20. Single-module based experiment results showed that the use of the B20 mixture in comparison with conventional diesel fuel can increase the module’s open circuit voltage up to 12% and consequently increase the maximum output power of the module by 25%.