Furan and methyl heptanoate are potential substitute fuels for high energy density and renewability. Free spray diffusion after injection greatly influences the combustion process. In this study, the effects of free diffusion of pure diesel (D100) and four blends (F10, F20 (10 %, 20 % furan and 90 %, 80 % diesel), MH10, MH20 (10 %, 20 % methyl heptanoate and 90 %, 80 % diesel)) spray on combustion characteristics were investigated in a constant volume bomb. The results show that the effects of fuel properties on gas-liquid area and gas-to-liquid ratio of area (GTL ar ) at free diffusion stage are more significant. The GTL ar of F20 and MH20 reaches about 1.86, while D100 is 0.82. At 140 MPa, the peak flame area of F20 and MH20 exceeded 750 mm 2 , while D100 was near 600 mm 2 . When the gas-liquid area and GTL ar increase, the flame temperature increases. At 140 MPa, the flame KL of F20 and MH20 is net-zero, while the flame KL of D100 is above 3. It reveals that blending furan and methyl heptanoate is beneficial to reduce soot formation due to higher temperature and oxygen content, respectively. These findings provide a basis for the engine application and bioenergy efficient utilization of furan and methyl heptanoate as renewable energies.
Co/MgO, Co/SiO 2 and Co/Hβ catalysts were prepared by incipient wetness impregnation. The formation of MgO-CoO solid solution and MgCo 2 O 4 spinel in Co/MgO resulted in high dispersions of Co on MgO even at the low calcined temperatures and the high Co loadings. The second impregnation of Co on Co/MgO enhanced Co cations in surface/subsurface of catalysts, which led to the enlarged metallic Co particle sizes by H 2 reduction. Comparatively, the highly dispersion of Co was only observed on SiO 2 and Hβ at the low Co loadings owing to the Co δ + species of strong interactions with these supports. The solid solution/spinel and the strongly interacted Co δ + species induced the Co cations reduced at higher temperatures with obtaining the small Co particle sizes. These cases also significantly decreased the basicities of Co/MgO depending on calcined temperature and Co loadings, and increased the acidic sites of Co/SiO 2 and Co/Hβ with obtaining enhanced acidities, respectively. During hydrogenolysis processing, the basic sites of Co/MgO triggers the splitting of acyl C O bond of methyl heptanoate to form heptanal and methanol, followed by further hydrogenation of heptanal to 1-heptanol. While the acidic Co/SiO 2 and Co/Hβ induce the cracking of ether C O bond to heptanoic acid and CH 4 . Heptanoic acid intermediate is then converted into C 6 and C 7 alkanes by the parallel decarbonylation and HDO pathways, respectively. The activity and product distribution could be facilely mediated by the synergistic catalysis of metal and acid/base. Under optimal conditions, the maximal 1-heptanol and summed C 6 /C 7 alkanes yields of 55% and 89% were observed over Co/MgO and Co/SiO 2 with desire Co loadings, respectively, indicating the promising applications of these catalysts in hydrogenolysis of vegetable oils.
The experimental measurements for liquid viscosities of four fatty acid methyl esters, including methyl hexanoate, methyl heptanoate, methyl caprylate, and methyl nonanoate, were carried out with a falling-cylinder viscometer. For the present measurement, the temperature ranges were from 292 K to 362 K and the pressure was reached to 30 MPa. The combined expanded relative uncertainty of the viscosity measurements was within 0.03 with 0.95 confidence level. The viscosity data for each studied esters were correlated by Andrade-Tait equation, and the average absolute relative deviation between the experimental data and calculated values is 0.31%, 0.44%, 0.38%, and 0.25% for methyl hexanoate, methyl heptanoate, methyl caprylate, and methyl nonanoate, respectively. The maximum absolute relative deviation is 1.09%, 1.28%, 1.28%, and 0.75%.
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