Experimental burning velocities of ethanol-water-air at elevated pressure and temperature

International audienceAnhydrous ethanol can be considered as one of the main alternatives to replace fossil fuels. However, the removal of water consumes the greatest fraction of the energy necessary for its production. Thus, the use of hydrous ethanol arises from a new fuel possibility and it has been successfully tested in a device such as a spark-ignition engine. For this reason, there is a need for the determination of fundamental properties of the ethanol-water-air mixtures. There are few experimental works in this area and the majority of them have been carried out in test conditions of pressure up to 1 atm. Thus, the main goal of the present work is to bridge this data gap. For this, the laminar burning velocities and Markstein length of ethanol-water–air flames at water content up to 30% v/v over a range of equivalence ratios from 0.7 to 1.4 up to 5 MPa and 380 and 450 K were experimentally determined. The method used was a constant volume bomb method with a central ignition. The results were compared to literature data and with predictions carried out with CHEMKIN-PRO using the three different kinetic mechanisms. In general, the results of the mechanisms lead to an overprediction in relation to the experimental results, though all of them predicted the burning velocity peaks at an equivalence ratio close to 1.1, which agreed with the experiments. The experiments conducted that increased water content of water fuel mixtures have a tendency to remain stable under a stretch influence. Also, it is possible to observe a linear relationship describing the influence of the diluent on the laminar burning velocity

Optimization of adsorptive removal of α-toluic acid by CaO2 nanoparticles using response surface methodology

The present work addresses the optimization of process parameters for adsorptive removal of α-toluic acid by calcium peroxide (CaO2) nanoparticles using response surface methodology (RSM). CaO2 nanoparticles were synthesized by chemical precipitation method and confirmed by Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis which shows the CaO2 nanoparticles size range of 5–15 nm. A series of batch adsorption experiments were performed using CaO2 nanoparticles to remove α-toluic acid from the aqueous solution. Further, an experimental based central composite design (CCD) was developed to study the interactive effect of CaO2 adsorbent dosage, initial concentration of α-toluic acid, and contact time on α-toluic acid removal efficiency (response) and optimization of the process. Analysis of variance (ANOVA) was performed to determine the significance of the individual and the interactive effects of variables on the response. The model predicted response showed a good agreement with the experimental response, and the coefficient of determination, (R2) was 0.92. Among the variables, the interactive effect of adsorbent dosage and the initial α-toluic acid concentration was found to have more influence on the response than the contact time. Numerical optimization of process by RSM showed the optimal adsorbent dosage, initial concentration of α-toluic acid, and contact time as 0.03 g, 7.06 g/L, and 34 min respectively. The predicted removal efficiency was 99.50%. The experiments performed under these conditions showed α-toluic acid removal efficiency up to 98.05%, which confirmed the adequacy of the model prediction