Mass Ratio Of Methanol Research Articles

Effects of surfactant CTAB on performance of flat-plate CLPHP based on PEMFC cooling

In this study, passive flat-plate closed-loop pulsating heat pipe (CLPHP) cooling is proposed to address the structural characteristics and cooling requirements of proton exchange membrane fuel cells (PEMFCs). Through visual images, non-visualized temperature and pressure measurements, and theoretical analysis, the effect of surfactant cetyltrimethylammonium bromide (CTAB) on the performance of a binary non-azeotropic mixed working medium flat-plate CLPHP with a 40% filling ratio (FR) and 5:1 mass ratio of methanol and deionized water was studied. It was found that the addition of surfactant CTAB reduced the surface tension and increased the shear friction force of the working fluid. The optimal CTAB concentration was 20 ppm, at which the start-up critical heat flux of the flat-plate CLPHP was reduced. At a heating power of 400 W, the heat transfer resistances reduced by 29.9%, which improved the heat transfer power of the flat-plate CLPHP. The backflow of the liquid-phase working medium at the bottom of the elbow in the evaporation section was promoted, dry-out phenomenon was avoided, temperature fluctuation of the flat-plate CLPHP was reduced, and temperature stability of the PEMFC was improved.

Experimental study on the influence of airflow velocity on frosting and defrosting performance of compact precooler under actual air humidity condition

Due to the precooler of hypersonic vehicle is frosted during the process of operation, the flow channel is blocked and the performance of engine is affected, which resulting in the decline of thrust and specific impulse. Therefore, for the purpose of maintain the performance of aero-engine, it is necessary to defrost the precooler. In order to study the influence of the airflow velocity on the frosting and defrosting performance of the compact precooler under actual air humidity condition, the frosting and defrosting performance of the microtubule precooler are experimentally studied in the wind tunnel under the conditions of air humidity of 1.8 g/kg and main flow velocities are 10 m/s, 20 m/s and 30 m/s, respectively. Methanol is utilized as the defrosting solvent, the mass ratio of methanol ranges from 0.8 to 1.2. The experimental results reveal that under the frosting experimental conditions, frost layer quickly condenses on the outside of tube bank, the wall surface temperature and heat transfer rate decrease dramatically, but the pressure drop coefficient increases sharply. It indicates that the frosting has an adverse effect on throughflow characteristics and heat transfer performance of the precooler. However, for the defrosting experiments, the wall temperature increases significantly, the defrosting effect and heat transfer rate are improved obviously and the pressure loss coefficient drops distinctly. In addition, with the increase of airflow velocity, the pressure drop coefficient increases sharply, but the coverage area of the frost layer gradually decreases, it manifests that increasing the main flow velocity is beneficial to suppress the formation of the frost layer. Through the analysis of experimental results, it can be found that within the range of experimental study parameters, the optimal defrosting performance can be obtained when the mass ratio of methanol is about 1.1. Moreover, with the increase of mass ratio of methanol, although the amount of condensation decreases, the condensation gradually evolves from the fluffy frost layer to the mixture layer of frost and ice, and eventually develops to whole ice layer.

Optimization of one-step production of biodiesel by Sulfuric acid/Stannic oxide-Hangjin2 clay catalyzed xanthoceras sorbifolia bunge kernel

ABSTRACT In this study, biodiesel has been successfully prepared from Xanthoceras sorbifolia seed kernel by SO4 2-/SnO2-Hangjin2#clay as catalyst. Based on the Central Composite Design method, the effect of the various parameters influencing the biodiesel process have been studied and optimized. The maximum yield of biodiesel (90.67%w/w) can be obtained when the mass fraction of the catalyst is 0.7%, the mass ratio of methanol to oil is 4:1 V/m, the methanol content in the oil is 12%, and the reaction temperature achieves 81°C。Besides, the consequence of Infrared spectroscopy and Gas chromatography can assure the production of biodiesel from the xanthoceras sorbifolia bunge oil. Based on these results, it can be concluded that Xanthoceras sorbifolia bunge seed oil is an acceptable non-edible feedstock for biodiesel production.

Controlling Polymorphism of Carbamazepine Nanoparticles in a Continuous Supercritical-CO2-Assisted Spray Drying Process

Controlling polymorphism in the transition from batch to continuous crystallization represents a major obstacle for the pharmaceutical industry. This work demonstrates a novel methodology to control the polymorphism of carbamazepine (CBZ) nanoparticles, a highly polymorphic BCS class II drug, using a continuous supercritical CO2 antisolvent-assisted nano spray drying (SASD) process. We show herein that when supersaturation conditions are achieved in the high-pressure SASD nozzle in the presence of anionic additives (e.g., sodium stearate, sodium dodecyl sulfate), nanoparticles of the metastable CBZ form II (using sodium stearate) or the stable CBZ form III (using sodium dodecyl sulfate) are obtained from methanol solutions, respectively. This novel methodology provides control over the final polymorphic form of CBZ obtained by (1) templating the desired polymorphic form when supercritical CO2 supersaturates the CBZ-additive methanol solution in the nozzle and (2) avoiding/minimizing the occurrence of any possible polymorphic transformation by immediately spray drying the supercritical antisolvent induced suspension into a dried fine powder. These results contrast with those obtained when using nonsupersaturating conditions in the SASD nozzle (amorphous CBZ is obtained, regardless of the additive used) and when using conventional spray drying (SD) where there is no antisolvent effect in the nozzle (CBZ form IV is obtained, regardless of the additive used). The impact that the mass ratio of methanol and supercritical CO2 has on the supersaturation and consequently on the polymorphic outcome of carbamazepine obtained from batch and continuous supercritical CO2 antisolvent crystallization processes is also discussed.

Investigating and modeling PET methanolysis under supercritical conditions by response surface methodology approach

Polyethylene terephthalate (PET) is one of the most widely used raw materials in chemical industry. Chemical recycling of the waste PET is a sustainable way not only considering the economic benefit but also the environmental goals. This paper focused on the effects among three foremost variables (methanolysis temperature, time, and mass ratio of methanol (MeOH) to PET), established a mathematical model depicted the complete effects of the parameters on the process, and sought the optimal solution of this PET methanolysis reaction. Response surface methodology (RSM) was used to model and analysis the recycling process of dimethyl terephthalate (DMT) from waste PET under supercritical methanol conditions. Methanolysis temperature and time could increase the DMT yield. Mass ratio of MeOH to PET hardly affected DMT yield when the methanol is excess. Different operation parameters including reaction temperature (240–320°C), reaction time (15–120min), and MeOH to PET mass ratio (6:1–10:1) were modeled and optimized using RSM. The quadratic equation with mathematical transformation (square root) modified was established for predicting the DMT yield and evaluated the validity on the basic of analysis of variance (ANOVA). The result indicated that the MeOH to PET mass ratio and relative term exhibit a less significant influence on the response surface in comparison to reaction temperature and time in the range of the experiment conditions. Prediction made by the developed model was in reasonably good agreement with the test runs. Under the optimal condition, the yield of DMT reached 99.79% which was much closer to the extent of the complete reaction.

Biodiesel Production through Direct Transesterification of Microalgae with Alcohol via Ultrasonic Wave

A one-step extraction/transesterification process was developed to directly convert microalgae into biodiesel in the presence of catalyst, KOH using ultrasonic irradiation. The influences of various parameters on the transesterification reaction, including the reaction time, temperature, catalyst concentration, methanol to microalgae mass ratio and ultrasonic power, were investigated. And the optimum conditions for the transesterification process have been obtained as mass ratio of methanol to microalgae as 4:1, catalyst concentration of 7wt.%, temperature as 70oC and ultrasonic power as 100W with an irradiation time of 30 min by orthogonal experiments L9(34 )．Under these conditions, the conversion of fatty acid methyl esters was up to 4.0%.

Study of variables affecting the synthesis of biodiesel from Madhuca Indica oil

AbstractBiodiesel derived from non‐edible Madhuca Indica oil (MIO) seems to be a better alternative to diesel oil in India. In the present work, effects of reaction variables such as mass ratio of methanol to oil, catalyst concentration, reaction time and reaction temperature on biodiesel yield were studied. The acid value of the commercially available MIO is high, and hence a two‐step process was used to produce biodiesel from MIO. In the first step, the acid value of the MIO was reduced to less than 1 mg KOH/g, using acid‐catalyzed transesterification. In the second step, the pretreated MIO was converted to biodiesel using alkaline‐catalyzed transesterification. From the experimental results, it is observed that the optimized conditions for biodiesel production are a 1 : 4 mass ratio of methanol to oil, 55 °C reaction temperature, 120 min of reaction time, and 1% sodium hydroxide catalyst. The properties of the MIO biodiesel were found to be within the biodiesel limits of the European Union. Hence, the MIO biodiesel can be used as a substitute for diesel for the sustainable development of rural areas and as a renewable fuel.