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Used cooking oil (UCO) biodiesel may be one of the most potential alternative fuels in China to lower the dependency on crude oil for transportation. An experimental study has been conducted to assess the interactions between biodiesel produced from UCO in Shanghai and elastomer materials on high-speed marine diesel engines by immersing elastomer materials into conventional fossil diesel, 5, 10, and 20%, of a volumetric blending ratio of UCO biodiesel and pure UCO biodiesel. The test duration is 168 h at different temperatures of 25, 50, and 70 °C. Meanwhile, the effects of the mixing ratio of UCO biodiesel and the immersion temperature on the compatibility of elastomer materials with UCO biodiesel were analyzed. The results revealed that elastomer materials such as nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), fluororubber (FKM), and silicone rubber (SR) exposed to biodiesel blends would reveal worse but acceptable changes than those exposed to petroleum diesel, including the slight increase of mass and volume and decline of tensile strength and hardness. FKM, NBR, and SR represented better compatibility with pure UCO biodiesel than diesel, and EPDM showed worse compatibility with UCO biodiesel as the blend ratio rises. In general, the recommended volumetric mixing ratio of UCO biodiesel should be no larger than 20%. The present study could be helpful for the investigation of UCO biodiesel blends as a potential fuel to satisfy the energy demand.

The idle start-go (ISG) system has been widely used, but there have been few relevant studies of its effect on emissions. This paper investigates fuel economy, total hydrocarbon (THC), carbon monoxide (CO), nitrogen oxides (NOx), particulate mass (PM), and particle number (PN) emissions from China VI gasoline direct injection (GDI) vehicles with and without ISG. Three test cycles were performed under hot start conditions, that is, the worldwide harmonized light vehicle test cycle (WLTC), the China light-duty vehicle test cycle (CLTC), and the USA federal test procedure-75 (FTP-75). About 28 idling phases were selected to specifically analyze the influence of ISG system. The results reveal that ISG system helps decrease fuel consumption, THC and CO emissions but aggravates NOx and solid PN emissions. Also, ISG system increases the proportions of sub-23 nm and nucleation-mode particle emission. Idling time plays a role in fuel economy, THC and CO emissions, while accelerated speed affects the emissions of THC, CO, NOx, and PN.