Exergoeconomic analysis and multi objective optimization of a solar based integrated energy system for hydrogen production

In the current study, an integrated renewable based energy system consisting of a solar flat plate collector is employed to generate electricity while providing cooling load and hydrogen. A parametric study is carried out in order to determine the main design parameters and their effects on the objective functions of the system. The outlet temperature of generator, inlet temperature to organic Rankine cycle turbine, solar irradiation intensity $\left(I\right)$, collector mass flow rate $\left({\dot{m}}_{col}\right)$ and flat plate collector area $\left(A_P\right)$ are considered as five decision variables. The results of parametric study show that the variation of collector mass flow rate between 3 kg/s and 8 kg/s has different effects on exergy efficiency and total cost rate of the system. In addition, the result shows that increment of inlet temperature to the ORC evaporator has a negative effect on cooling capacity of the system. It can lead to a decrease the cooling capacity from 44.29 kW to 22.6 kW, while the electricity generation and hydrogen production rate of the system increase. Therefore, a multi objective optimization is performed in order to introduce the optimal design conditions based on an evolutionary genetic algorithm. Optimization results show that exergy efficiency of the system can be enhanced from 1.72% to 3.2% and simultaneously the cost of the system can increase from 19.59 $/h to 22.28 $/h in optimal states.     

Estimation of the depth of frost penetration in both uniform and layered soils in frost-affected regions

One of the most important factors affecting pavement performance is climate, including frost action and precipitation. The performance of pavements in frost-affected regions depends to a large degree on the depth of frost penetration. In this paper, a simple predictive tool is developed to calculate a new correction coefficient depending upon the thermal ratio and fusion parameter. The new correction coefficient can be used in follow-up calculations to estimate the depth of frost penetration for both uniform and layered soils in frost-affected regions to evaluate the performance of pavement. The results of the proposed method are found to be in excellent agreement with reported data in the literature with average absolute deviation being less than 0.8%. The predictive tool is simple, straightforward and can be readily implemented in any standard spreadsheet programme leading to accurate, smooth and non-oscillatory data points. The prime application of the method is as a quick-and-easy evaluation tool in conceptual development and scoping studies in which the depth of frost penetration for both uniform and layered soils in frost-affected regions is being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.     

Effect of microwave irradiation on crystal growth of zeolitized coal fly ash with different solid/liquid ratios

In the present work, coal fly ash (CFA) was converted to zeolite (CFAZP) experimentally at atmospheric pressure via a conventional hydrothermal heating for 6 h at low temperature (90 ± 3 °C) followed by microwave irradiation for 30 min. The synthesized products were characterized using XRD, TGA/DTA, SEM, PSD, BET, and cation-exchange capacity (CEC) techniques. The effect of microwave on the crystal growth of nucleated CFAZP at different solid/liquid ratios (suspended CFA mass to NaOH solution volume, g/mL) was studied. A three-variable, three level central composite statistical experimental design was applied to investigate the effect of the independent variables on the response function defined as the ratio of the characteristic peak intensity at 2θ: 28° of a sample to that of the same peak of a sample run for 24 h with conventional heating. The relative peak intensity of CFAZP as high as 97% was achieved under optimum experimental conditions with 1 M of NaOH concentration, 6 h of conventional heating followed by 30 min microwave irradiation with a solid/liquid ratio of 0.40 g/mL. Under constant microwave energy, higher solid/liquid ratios led to higher relative peak intensity of the product.     

Study of different fouling mechanisms during membrane clarification of red plum juice

In this study, the flux decline mechanisms were identified during membrane clarification of red plum juice at several processing parameters, including pore size, membrane type, transmembrane pressure, temperature and velocity. The results were used to investigate the effect of changes in operating conditions on the intensity of membrane fouling. Also, scanning electron microscopy (SEM) was used for analysing fouling‐layer morphology. These results showed that the main mechanism responsible for membrane fouling was cake formation (over 95% fitness) occurring in the first stage of the process. Intermediate, standard and complete blockings were formed during most of the runs as filtration proceeded. The results also indicated that increasing the temperature from 30 to 40 °C was the most effective factor in decreasing cake‐layer fouling, reducing it by about 66.7%. Furthermore, an increase in processing velocity of up to 0.5 m s^?1 had the greatest effect on intermediate blocking, reducing it by about 86.1%. Also, increasing pressure up to 2.9 bar completely eliminated standard blocking and complete blocking. Finally, microstructure analysis of membrane using SEM confirmed that cake formation had the greatest impact on membrane fouling.     

Validation of CFD model of multiphase flow through pipeline and annular geometries

Accuracy of prediction of pressure losses plays a vital role in the design of multiphase flow systems. The present study focused on the development of a computational fluid dynamics model to predict these parameters conveniently and accurately. The main objective was to validate the developed model through comparison of its simulation results with existing experimental data and empirical correlations. Both pipeline and annular geometries were considered for validation. Several data sets that involved a significant variation in process conditions were used for the validation. All three phases—liquid (water), gas (air), and solid (sand)—were taken into account. The simulations were conducted using the workbench platform of ANSYS Fluent 16.2. The Eulerian model of multiphase flow and the Reynolds stress model of turbulence closure available in Fluent were used for the present study. The average velocities and volumetric concentrations of involved phases were specified as the inlet boundary conditions. The stationary surfaces of the flow channels were hydrodynamically considered as either smooth or rough walls, and the outlets were regarded as being open to the atmosphere. The simulation results of pressure loss showed a good agreement with the corresponding measured values as well as with the predictions of well-established correlations.     

An Artificial Neural Network for Solving Distributed Optimal Control of the Poisson’s Equation

Neural Processing Letters - This paper presents a simple and efficient method based on artificial neural network to solve distributed optimal control of Poisson’s equation with Dirichlet...