Search

Abundant alcohols, including ethanol, propanol, butanol, and pentanol, are expected to be used in compression ignition engines to ease the shortages of fossil fuel. The various alcohols have quite a different combustion and emission characteristics in the engine due to the changes in molecular structures. In this paper, a series of experiments were conducted on a modified common-rail diesel engine fueled with diesel/alcohols blended fuels in a wide operating range. The effects of alcohol chain length, oxygen content, and molecular structure on engine combustion and emission characteristics are studied systematically. The experimental results show that the blending of alcohols increases the peak values of in-cylinder pressure and maximum pressure rising rate. Besides, the combustion duration and ignition delay are mainly affected by oxygen content and isomer structure. The addition of short-chain alcohols will significantly reduce the total mass of particulate matter (PM) emissions, while the CO and HC emissions increase appropriately. The CO, HC, aldehydes, and ethylene emissions are mainly affected by carbon chain length and isomer structure. For PM emissions, the carbon chain length, molecular structure, and oxygen content of alcohol fuels have different influences on PM number, PM mass, and particle size distributions. The shorter carbon chain of alcohol leads to smaller particle size, and higher oxygen content leads to lower total particle mass. [ABSTRACT FROM AUTHOR]

In the actual engineering design, it is too conservative for the calculation results for the urban sludge sintered shale brick to use the shear strength formula in the Design Specifications of Masonry Structure. To more effectively calculate this formula, this paper researches the straight joint shear performance test of urban sludge sintered solid shale bricks and porous brick masonry, and analyzes the failure mode of two kinds of brick masonry, and reaches the proposed formula of the straight joint shear strength. Then, this paper compares the proposed formula with the corresponding formulas in the specification, and reaches a high safety stock of the formula in the specification, and needs to correct the coefficient of material properties in the formula in the specification.

The main chemical composition of paper-making white mud is CaO, which is one of the reasons that affect the bursting performance of brick lime. In this study, shale was used as the main raw material, and the shale brick obtained by calcination was added after different amounts of paper-making white mud (0, 10%, 15%, 20%). The results show that when the content of papermaking white mud is controlled within 10%, it can meet the national standard "Sintered Ordinary Bricks" (GB/T 5101-2017), and effectively reduce the occurrence of brick body lime burst. [ABSTRACT FROM AUTHOR]

Detailed high-fidelity kinetic models of fuels are of great significance by providing guidance for the improvement of the combustion performance in engines and promising the reduction of design cycle of new concept combustors. However, the kinetic modeling works on Chinese RP-3 kerosene, the most widely used civil aviation fuel in China, are meager to date. In this study, a kinetic model, including a surrogate fuel and its combustion kinetic mechanism, were developed to describe the combustion of RP-3. Firstly, a surrogate comprised of components n-dodecane, 2,2,4,6,6-pentamethylheptane (PMH), n-butylcyclohexane and n-butylbenzene (22.82/31.30/19.19/26.69 mol%) was proposed based on the combustion property target matching method. These components are all within the typical molecular size (C10-C14) of jet fuels and thereby can potentially improve the ability of the surrogate in emulating the properties that depend on molecular size. Experiments were then carried out in a heated rapid compression machine and a heated shock tube to evaluate the performance of the surrogate in reproducing the combustion behavior of the target fuel over wide conditions. It is found that the surrogate can reproduce the autoignition characteristics of RP-3 very well. A chemical kinetic mechanism was developed to describe the oxidation of this surrogate. This mechanism was assembled using a published n-butylbenzene sub-mechanism and our previous sub-mechanisms for the other pure components, and was assessed against the present experimental data. The results showed that the simulations agreed well with the experimental data under the investigated conditions, demonstrating that the composition of the surrogate and its mechanism are appropriate to describe the combustion of RP-3. The first-stage ignition negative temperature coefficient behavior and the evolution of key radicals were investigated using the kinetic model. [ABSTRACT FROM AUTHOR]

Frosting and lime burst tests were carried out on sintered shale brick with white clay content of 20% in papermaking. In this paper, the effects of different treatment methods and sufficient stirring on the lime bursting degree of the raw material were studied, and compared with the lime bursting degree of ordinary sintered shale brick. After comparing the test data with the national standard GB 5101-2003 "Fired common bricks", it is concluded that this kind of new wall material is more serious than ordinary sintered shale brick in the aspect of frosting and lime bursting. However, all of them are within the allowable range of the national standard. [ABSTRACT FROM AUTHOR]

The regenerated sintered shale brick was prepared by calcining taking shale as main raw material, adding different dosages of waste mixture. Test result showed that the compressive strength of regenerated sintered shale bricks has a certain degree of influence on lime burst. In this experiment, the building waste regenerated and sintered shale brick samples meet the requirements of first-class sintered bricks. In this paper, through the failure characteristics and morphology of the samples, the experimental data were analyzed to analyze the factors affecting the lime burst of the shale bricks from the construction waste regeneration. [ABSTRACT FROM AUTHOR]

Through the regeneration of sintered shale bricks with 30% of construction waste, the effects of sintering process on the performance of regenerated sintered shale bricks were studied under different sintering temperatures, heating rates and firing times. The sintering process of regenerated sintered shale bricks can be obtained when the heating rate is 1 °C/min, the calcination temperature is controlled at 1050 °C, and the firing time is kept within 4~10h. The strength of the obtained regenerated sintered bricks can meet the requirements of MU10 specified in GB 5101-2003 "Sintered Ordinary Bricks", indicating that it is feasible to use recycled waste materials to prepare regenerated sintered shale bricks. [ABSTRACT FROM AUTHOR]