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This paper updated the perception of theoretical thermal efficiencies of reciprocating engine cycles by the analysis of six ideal cycles (Diesel, Joule-Brayton, Otto, Atkinson, Sabathe and Song). It was theoretically elucidated that more available energy remains in exhaust gas at higher load than at lower one, testifying that the exhaust waster energy recovery is more important at higher load than at lower one. A supercharged cycle was theoretically demonstrated to have lower thermal efficiency than its counterpart naturally-aspirated one, while supercharged engines had been always considered to have higher thermal efficiency. The thermal efficiencies of gasoline engines were first derived, testifying that a homogeneous spark-ignition gasoline engine at part-load has less thermal efficiency than its corresponding Otto cycle and can achieve a higher thermal efficiency by retarding (or advancing) inlet valve closing than by throttling intake flow.

The kinetic study of the reaction of 1-hydroxyethyl radicals (CH3CHOH) with nitric oxide (NO) was performed over the temperature range of 200–1100 K and the pressure range of 1.0 × 10–5to 10.0 bar. The geometries of all of the stationary points were optimized at the B3LYP/6–311++G(df,pd) level of theory, and the energetics were refined at the CCSD(T)/cc-pVTZ level of theory. Eight reaction pathways were explored, and they all consisted of a common first step involving the formation of a deep potential well. Three favorable pathways were confirmed, and they were the channels producing the adducts CH3CO(NHOH) and CH3NOHCHO and the products H2O and CH3CNO. The Rice–Ramsperger–Kassel −Marcus-canonical variational transition state theory method with Eckart tunneling correction was used to calculate the rate coefficients of the system. The predicted total rate coefficients agree well with the available literature data and show negative temperature dependence and positive pressure dependence. The reaction producing the adduct CH3CHOHNO in the entrance channel is dominant at 1.0 bar, and its branching ratio is almost 100% at a temperature less than 670 K. At 3.0 Torr, it is only dominant at a temperature less than 600 K.

The reaction of nitric oxide (NO) with propargyl radical (C3H3) was investigated at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(df, pd) level of theory. The rate coefficients of the system were determined by using the RRKM–CVT method with Eckart tunneling correction over a temperature range of 200–800 K and a pressure range of 1.0 × 10–4to 10.0 bar. Eight channels proceeding via the barrierless formation of excited intermediate ONCH2CCH or CH2CCHNO at the first step were explored. Three favorable channels (i.e., channels producing adduct of ONCH2CCH and CH2CCHNO and products of HCN and H2CCO) were confirmed. The rate coefficients of channels producing adduct of ONCH2CCH and CH2CCHNO are comparable and have weak negative temperature dependence and positive pressure dependence. Channel producing products of HCN and H2CCO is more important at low pressure and high temperature and less important after pressure greater than 1.0 × 10–2bar (with a branching ratio less than 6% at 0.1 bar).

Ab initiostudy of the reactions of n-heptyl radicals(1-C7H15, 2-C7H15, 3-C7H15, and 4-C7H15) with methanol was conducted over the temperature range of 300–1500 K. Transition states for the reaction channels producing C7H15OH, CH3, C7H15OCH3, H, C7H16, CH2OH and CH3O were identified and the geometries of all stationary points were calculated at BB1K/MG3S level of theory. The potential barrier heights of the corresponding transition states were predicted by the CBS-QB3//BB1K and G4//BB1K methods, indicating that the eight H-abstraction channels are more kinetically favorable than the channels where OH transfers from CH3OH to C7H15and where the C7H15OCH3+H products are given. The rate constants of H-abstraction channels were calculated with TST and TST/Eck. Both the forward and reverse rate constants have positive temperature dependence and the tunneling effect is only important at the temperature lower than 700 K. For the reactions of H-atom abstraction from methyl in CH3OH by n-heptyl, a reverse and the corresponding forward rate constant are roughly equal. For the reactions of H-atom abstraction from OH in CH3OH by n-heptyl, a reverse rate constant is larger by several orders of magnitude than the corresponding forward one.

The effect of ethanol on the ethylene consumption in fuel-rich, premixed, laminar, burner-stabilized flames at atmospheric pressure was investigated. A pure ethylene flame and three ethylene/ethanol flames with different ethanol fractions were simulated at the same equivalence ratio. The results showed that the different reaction rates for ethylene consumption in the flames were related to the reaction kinetics in these flames with an insignificant thermal effect. Changes in key radical concentrations in the flames were observed depending upon the initial ethanol mole fraction in the fuel, and the reaction pathways responsible for the production and destruction of ethylene were identified. The chemical behaviors differed significantly at different flame heights above the burner. At the flame height with a temperature of 769 K, a decrease in the OH concentration was responsible for the reduction in the reaction rate for ethylene consumption with the addition of ethanol. At the flame height with a temperature of 1470 K, the normalized ethylene concentration in the flames increased with the increase of the initial ethanol fraction in the fuel, the reason for which appeared to be the decomposition reactions into ethylene rather than the changes of species pool in the flames.

Cobalt-containing catalysts supported on ZSM-5 zeolite and mesoporous siliceous SBA-15 were prepared and characterized by nitrogen sorption, X-ray diffraction, scanning electron and transmission electron microscopies, energy-dispersive X-ray, Fourier transform infrared, ultraviolet–visible diffuse reflectance, X-ray photoelectron spectroscopies, and temperature-programmed desorption of ammonia measurement. The effect of cobalt loading ratio on the selective catalytic reduction (SCR) of nitrogen oxides (NOx) with ammonia was investigated. The existing Brønsted acid sites contributed to the cobalt species finely dispersed within the ZSM-5 zeolite, either as isolated cobalt ions anchored at α, β, and γ sites, or as amorphous cobalt oxides enriched on the ZSM-5 surface. NOxconversion profiles of Co/ZSM-5 exhibited two peaks. The low-temperature peak (<300 °C) was induced by cobalt ions at β and γ sites, while the high-temperature peak (>300 °C) was assigned to the amorphous and crystalline cobalt oxides. With increasing cobalt content, the intensity of low-temperature peak was enhanced monotonously, and the peak position remained constant. Increasing cobalt content promoted the high-temperature peak to shift toward lower temperatures. NOxconversion profiles of Co/SBA-15 only exhibited a high-temperature peak. For Co/SBA-15, the poor dispersion of cobalt species was derived from the absence of Brønsted acid sites. The activity of Co/SBA-15 catalysts was lower than that of the Co/ZSM-5 catalysts due to inactive cobalt ions anchored on isolated Si–OH groups, and agglomerated cobalt oxides within the SBA-15 channels blocking the reactant pathway to active sites.