Experimental investigation into the effects of Argemone biodiesel/diesel blends on cyclic variations in a multi-cylinder CRDI engine

Internal combustion engines suffer from high cyclic variations that result in higher emissions,lower efficiency,higher fuel consump-tion and poor drivability.The purpose of this study is to investigate how Argemone mexicana biodiesel(AGB)/diesel blended fuels affect the cyclic variability of combustion parameters such as maximum cylinder pressure(Pmax)and indicated mean effective pressure(IMEP)in a four-cylinder turbocharged intercooled common-rail direct injection engine under various engine loading conditions.The chemical and physical properties of AGB produced from A.mexicana oil were measured and compared according to the ASTM D6751 standards.In various volumetric ratios,AGB and diesel fuel were blended as D100,AB10(10%AGB+90%D100),AB20(20%AGB+80%D100)and AB30(30%AGB+70%D100).The IMEP and Pmax time-series data were collected over 200 consecutive cycles at low,partial and high engine loads at a constant engine speed of 2000 rpm.The coefficients of variation(COV)of combustion parameters(Pmax and IMEP)were measured for different AGB/diesel blends and found to be within acceptable limits.The results show that COV_(Pmax) and COV_(IMEP) decrease as the engine load increases.It was observed that at low load,AB10 has the lowest COV(Pmax,IMEP),and at partial and high load,AB20 has the lowest COV(Pmax,IMEP)among all the blends.

Polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls in surface soil from the Tibetan Plateau

Concentrations of Polychlorinated dibenzo-p-dioxins and dibenzofurans（PCDD/Fs） and polychlorinated biphenyls（PCBs） in soil samples from Tibetan Plateau were determined. The average concentration of total 2,3,7,8-PCDD/Fs was（2.30 ± 1.02） pg/g, and World Health Organization Toxicity Equivalency（WHO-TEQ） average concentration was（0.013 ± 0.010）pg WHO-TEQ/g. The average concentration of ∑PCBs（7 indicator PCB and 12 dioxin like-PCB congeners） was（16.2 ± 9.25） pg/g, and WHO-TEQ average concentration was 0.043 ±0.049 pg WHO-TEQ/g. Comparing to previous studies in similar environmental conditions,PCDD/Fs and PCBs in this study showed a relatively lower concentration. The altitude dependences of PCDD/Fs and PCBs were also studied. Total organic carbon（TOC） normalized concentrations presented a quadratic relation with the altitudes, and an inflection could be found on the parabola of the total concentrations and some congeners of high concentration.The concentrations decreased with altitudes below about 4500 m above sea level（a.s.l.）, while they increased with altitudes above it. These phenomena indicate that cold condensation of PCDD/Fs and PCBs would happen above 4500 m a.s.l, on the Tibetan Plateau.