Combustion analysis of a light duty diesel engine using oxygen-enriched and humidified combustion air

The present work presents the results of 3D CFD combustion simulations of a current production 4-cylinder turbocharged Diesel engine using oxygen-enriched and humidified combustion air. Enriched Air (EA) is supposed to be produced by desorption from water, exploiting the different Henry constants of N2 and O2. Simulation results show that EA permits to increase the engine thermal efficiency (up to 10%) and drastically reduces soot emissions but increases in-cylinder peak pressure and NOx emissions. Combustion air humidification helps to reduce NOx increment, without losing the advantage in terms of thermal efficiency and in soot reduction, even if NOx emissions cannot be reported to the base case values.

Predicting the phase behavior of hydrogen in NaCl brines by molecular simulation for geological applications

Hydrogen is targeted to have a significant influence on the energy mix in the upcoming years. Its underground injection is an efficient solution for large-scale and long-term storage. Furthermore, natural hydrogen emissions have been proven in several locations of the world, and the potential underground accumulations constitute exciting carbon-free energy sources. In this context, comprehensive models are necessary to better constrain hydrogen behavior in geological formations. In particular, solubility in brines is a key-parameter, as it directly impacts hydrogen reactivity and migration in porous media. In this work, Monte Carlo simulations have been carried out to generate new simulated data of hydrogen solubility in aqueous NaCl solutions in temperature and salinity ranges of interest for geological applications, and for which no experimental data are currently available. For these simulations, molecular models have been selected for hydrogen, water and Na+ and Cl− to reproduce phase properties of pure components and brine densities. To model solvent-solutes and solutes-solutes interactions, it was shown that the Lorentz-Berthelot mixing rules with a constant interaction binary parameter are the most appropriate to reproduce the experimental hydrogen Henry constants in salted water. With this force field, simulation results match measured solubilities with an average deviation of 6%. Additionally, simulation reproduced the expected behaviors of the H2O + H2 + NaCl system, such as the salting-out effect, a minimum hydrogen solubility close to 57 °C, and a decrease of the Henry constant with increasing temperature. The force field was then used in extrapolation to determine hydrogen Henry constants for temperatures up to 300 °C and salinities up to 2 mol/kgH2O. Using the experimental measures and these new simulated data generated by molecular simulation, a binary interaction parameter of the Soreide and Whiston equation of state has been fitted. The obtained model allows fast and reliable phase equilibrium calculations, and it was applied to illustrative cases relevant for hydrogen geological storage or H2 natural emissions.

ADSORPSI AIR DARI CAMPURAN UAP ETANOL-AIR DENGAN ZEOLIT SINTETIS 4A DALAM PACKED BED DALAM RANGKA PRODUKSI FUEL GRADE ETHANOL

Ethanol can be used as fuel if it has a purity of 99.5%, while ethanol distillation will stop at its azeotrop point, ie at 95.6%. Adsorption of molecular sieve is one of the methods to obtain ethanol with level above the azeotropic point. Adsorbent that serves as molecular sieve is synthetic zeolite 4A. The adsorbent has a pore diameter of 3.9 Ǻ, then water and ethanol each has a molecular diameter of 2.75 Ǻ and 4.4 Ǻ. Hence the adsorbent is selective against the ethanol-water mixture. The purpose of this research is to obtain ethanol above its azeotropic point and to study the relationship between the influence of flow rate (Vz) and temperature (T) to changes in the number of mass transfer coefficient (kc), radial diffusivity (Der) and henry constants (H') which can be used as parameters in the design of adsorption tools on a commercial scale.This experiment was conducting by weighing zeolite 4A as much as 100 grams, then compiled and measured the height on packed bed column adsorbent. The heating regulator is switched on and set to a constant temperature of 80, 85, 90, 95 and 1000C. Ethanol 95.61% with 250 ml volume is put into three-neck flask, then heat to evaporate. Turn on the cooling back and adjust the amount of formed vapor rate by adjusting the faucet opening and the degree of voltage in the heating mantle. The magnitude of the vapor flow rate is set at 2, 4 and 6 liters / minute. The products is accomodated and samples were taken every minute to analyze the ethanol content.This adsorption process gives the highest yield of ethanol with 99.40% content. The steam flow rate of 2 lpm and the temperature of 800C is the optimum combination in this research because much of the water vapor adsorbed on the 4A zeolite grain is 7.93 grams. The numerical calculation provides the result that the value of Der in this experiment is 1.59.10-3 cm2 / men, and the relation of kc are the function of reynolds and H' the function of temperature are as follows: kc = 7,95.10^-3.(Re)^0,1639 and H' = 4,47.10^-3.exp(2565,26/T)

Determination of Henry Constants of Azelnidipine Enantiomers on Chiralpak AD Column at Different Temperatures

Simulated moving bed (SMB) chromatographic separation has become a highly promising method for chiral separation due to the less solvent consumption and efficient utilization of stationary phase. As reported, Azelnidipine exists two isomeric forms, it is necessary to product azelnidipine single enantiomer for medical safety and drug developmen. However, the separation of azelnidipine enantiomers on SMB is complex, requiring many operating parameters. And the SMB processes with temperature gradient (non-isotherm) mode may have significant advantages over the traditional isothermal mode. In this article, the Henry constants of azelnidipine enantiomers were determined with pulse experiments on Chiralpak AD column at different temperatures. It provided important references for the production of azelnidipine single enantiomer with non-isotherm SMB.

Prediction of CO2 Solubility in Aqueous DEA and MDEA Binary Solutions Using O'Connell's Expression

In this work, the CO2solubility predicted for amines of DEA and MDEA by using the OConnell (1964) expression as a base model. This expression fits between the solvent compositions and the thermodynamic properties beside the gas solubility. The solvent activity coefficient, Gibbs energy and Henrys law constants have been generated using Aspen plus data analysis tools. The self-interaction binary parameters (Margules parameters) have been calculated based on Henry constants values. The data input for this work depends on the amine system process conditions (temperature range between 298.15 K and 393.15 K), materials composition (concentrations of 10 wt%, 20 w% and 30 wt %). For both of the DEA and MDAE and the pressure fixed to be 101.3 KPa. The solubility values of this work give satisfactory results compared to the literature data.

A consideration of the correct calculation of thermodynamic parameters of adsorption

The Langmuir and Freundlich isotherm equations have been widely used for interpreting various adsorption processes. There are, however, many serious mistakes in the literature in determination or calculation of thermodynamic parameters, especially in the determination of the change in the free energy of adsorption using Langmuir, Freundlich and Henry constants. Many authors used these constants for the determination of ?G expressed instead of dimensionless in some concentration units (for example: l mol-1, l g-1, ml mg-1, etc.).