Band 10, Heft 2 -

In this research work, transesterification of castor oil with methanol and sulphuric acid catalyst has been carried out in a lab reactor of capacity 500 mL at various operating conditions (reaction temperature=35–65°C, pressure=1 atm, methanol/oil ratio=6:1 and 600 rpm). The effect of reaction temperature is considered, followed by the determination of kinetics of the production of biodiesel. Experimental results have been analysed with respect to three types of reaction kinetics, namely first-order irreversible reaction, second-order irreversible reaction and reversible reaction. For each of the schemes, the activation energy and Arrhenius constants were determined. The experimental data fits very well to second-order reversible reaction kinetics. Properties of fatty acid methyl ester (biodiesel) produced from castor oil have been experimentally determined and compared with standard values as given in EN 14214 norms.

Owing to the wide utilization of shell and tube heat exchangers (STHEs) in industrial processes, their cost minimization is an important target for both designers and users. Traditional design approaches are based on iterative procedures which gradually change the design and geometric parameters until satisfying a given heat duty and set of geometric and operational constraints. Although well proven, this kind of approach is time-consuming and may not lead to cost-effective design. The present study explores the use of non-traditional optimization technique called hybrid particle swarm optimization (PSO) and ant colony optimization (ACO), for design optimization of STHEs from economic point of view. The PSO applies for global optimization and ant colony approach is employed to update positions of particles to attain rapidly the feasible solution space. ACO works as a local search, wherein ants apply pheromone-guided mechanism to update the positions found by the particles in the earlier stage. The optimization procedure involves the selection of the major geometric parameters such as tube diameters, tube length, baffle spacing, number of tube passes, tube layout, type of head, baffle cut, etc. and minimization of total annual cost is considered as design target. The methodology takes into account the geometric and operational constraints typically recommended by design codes. Three different case studies are presented to demonstrate the effectiveness and accuracy of proposed algorithm. The examples analyzed show that the hybrid PSO and ACO algorithm provides a valuable tool for optimal design of heat exchanger. The hybrid PSO and ACO approach is able to reduce the total cost of heat exchanger as compare to cost obtained by previously reported genetic algorithm (GA) approach. The result comparisons with particle swarm optimizer and other optimization algorithms (GA) demonstrate the effectiveness of the presented method.

This study was motivated by the fact that differential scanning calorimetry (DSC)/differential thermal analysis (DTA) results in literature showed significant exothermic peaks while in overall, pyrolysis is an endothermic phenomenon. The specific heat of the decomposing tires has been determined with a new methodology: instead of assuming constant char properties throughout pyrolysis, the specific heat of evolving solids (char) was evaluated with increasing temperature and conversion. Measured specific heat values were observed to increase until pyrolysis was triggered at 250°C. Then, the specific heat of the solids decreased continuously until 400°C at which point they started to increase. This unexpected trend pointed out that the exothermic peak observed with DSC is an artefact generated by the control system of the apparatus. To overcome this limitation, the energy balance was performed over industrial data and the newly found heat capacity values. The enthalpy of pyrolysis was found to have a term dependent on the weight loss derivative, with a constant value of 410 kJ/kg tires. Two other terms for the enthalpy of pyrolysis have been identified, which were independent of weight loss. The first one is believed to correspond to the sulphur cross-link breakage at low temperature (65 kJ/kg), while the second one, at the final stage of pyrolysis, should correspond to charring reactions approaching the thermodynamic equilibrium (75 kJ/kg). Ultimately, this work proposes a new methodology to determine the enthalpy of pyrolysis with larger scale experimental data.

An Artificial Neural Network model of a UASB Reactor has been developed. The reactor treats bagasse wash water (containing organics), generated after washing of stored bagasse prior to its use in paper manufacture. In the process, biogas, a renewable source of energy is produced. As the UASB reactors (2×5,000 m 3 volume) operate mostly with feed having varying characteristics, therefore a special type of dynamic networks, called NARX networks have been used to model it for predicting biogas production rate. The input to the model is influent flow rate, inlet and outlet COD. Model is based upon 576 days plant data. NARX model architecture consists of input, output, and 2 hidden layers each having 10 neurons and utilizes 4 days delay. The developed ANN model represents the dynamic behavior of UASB reactor and recursively predicts and forecasts the biogas production rate with acceptable deviation with respect to actual production rate.

Production of biodiesel from castor oil (CO) using ultrasound-assisted has been investigated in this study. The objective of the present work was therefore to determine the relationship between various important parameters of the alkaline-catalyzed transesterification process to obtain a high reaction yield in a short time. The response surface methodology (RSM) was used to statistically analyze and optimize the operating parameters of the process. A central composite design (CCD) was approved to study the effects of the reaction time, the methanol to oil molar ratio, the ultrasonic cycle and the ultrasonic amplitude on reaction yield. The optimum conditions for alkaline-catalyzed transesterification of CO was found to be a reaction time of 540 s, methanol to oil molar ratio of 8.15:1,ultrasonic cycle of 0.73% and ultrasonic amplitude 64.34%. By exerting the calculated optimum condition in the process, the reaction yield reached 87.0494%. The results from the RSM analysis indicated that the reaction time has the most significant effect on the reaction yield.

This review article gives a comprehensive account of the extraction of actinide ions using room temperature ionic liquid-based solvent systems containing diglycolamide (DGA) or functionalized DGA extractants. These extractants include multiple DGA-functionalized ligands such as tripodal DGA (T-DGA) and DGA-functionalized calix [4]arenes (C4DGA). Apart from metal ion extraction behaviour, other important features of the ionic liquid-based solvent systems such as separation behaviour, luminescence spectroscopic results, thermodynamics of extraction and radiolytic stability of the ionic liquid-based solvents are also reviewed. Results from studies on DGA-functionalized task-specific ionic liquids (TSIL) are also included in this review article.