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The growing demand for hydrogen and the discovery of substantial methane reserves have led to a focus on converting methane to hydrogen. However, the high levels of CO2 emissions associated with traditional methane conversion (methane steam reforming) have raised concerns. As a result, researchers are looking for emission-free methods of producing hydrogen from methane with the aim of addressing these challenges. Methane catalytic cracking is an environmentally friendly route to produce hydrogen with zero greenhouse gas emissions. During this sustainable process, pure hydrogen is produced; however, it has not yet been industrialized due to the fact that it has not performed economically better than other processes such as methane steam reforming. However, the demand for pure hydrogen is rising every year, making methane cracking more attractive. Carbon black is also produced as a by-product, which is considered a valuable product that can be marketed to various industries. Although current hydrogen production processes including methane steam reforming, autothermal reforming, and partial oxidation have been developed and are well industrialized, the CO produced in these processes needs to be separated from the hydrogen stream, which is very complicated and expensive. To develop and modify methane cracking, different parameters involved in the process must be studied and improved, including catalysts, operating conditions, and suitable reactors. So in this study, different types of catalysts and their deactivation and regeneration are studied. It is also noteworthy that methane cracking kinetics, such as the reaction mechanism, the formation of carbon filaments, and the proposed models by researchers to predict the reaction rate have been presented. © 2025 selection and editorial matter, Mohammad Reza Rahimpour, Mohammad Amin Makarem and Parvin Kiani.
One of the most eco-friendly methods for replacing fossil fuels involves producing H2 through water splitting. Thermochemical cycles that use chemical reagents offer scalability advantages compared to other methods of H2 production from water splitting. In this chapter, various hydrogen production technologies are discussed based on pure and hybrid thermochemical cycles, involving two-, three-, and four-steps. In this regard, zinc oxide (ZnO/Zn), hybrid sulfur (HyS), sulfur-iodine (S-I), and metallic chlorides groups including magnesium-chlorine (Mg-Cl), copper-chlorine (Cu-Cl), vanadium-chlorine (V-Cl), and iron-chlorine (Fe-Cl) are evaluated in detail. Moreover, the main challenges, recent progress, and future directions of these cycles are introduced for analysis and design purposes. Finally, a comparative assessment of the thermochemical cycles is carried out, focusing on the global warming potential (GWP), the cost of H2 production, as well as exergy and energy efficiencies. It is found that in terms of GWP, the HyS and S-I cycles show the most promise, with GWP values of 0.5 and 0.48 kg CO2-eq/kg H2, respectively, while the V-Cl cycle exhibits the highest exergy efficiency (i.e., 77%). © 2025 selection and editorial matter, Mohammad Reza Rahimpour, Mohammad Amin Makarem, and Parvin Kiani.
The world is confronted with a pressing global climate crisis, and hydrogen is gaining ever greater recognition as a carbon-neutral energy carrier with the potential to significantly contribute to the process of decarbonizing economies. Nevertheless, the environmental consequences of various hydrogen production methods are occasionally underestimated. This chapter offers an extensive review (articles published from 2015 to 2023) of both environmental repercussions and costs associated with a wide array of hydrogen production methods. There are numerous technologies for hydrogen production, including thermochemical, electrochemical, and biological pathways utilizing renewable and nonrenewable sources. Nevertheless, the selection of these processes for hydrogen production relies heavily on environmental sustainability as determined by life cycle assessment (LCA). Hydrogen production LCAs have been categorized into four main stages including (i) defining the goal and scope, (ii) conducting a life cycle inventory (LCI) analysis, (iii) life cycle impact assessment (LCIA), and (iv) interpreting life cycle results, which are described in detail in this chapter. Finally, a comparison of the life cycles of various hydrogen production pathways is performed based on life cycle indicators. The initial comparison of the LCA studies focuses on global warming potential (GWP), followed by an evaluation of other metrics such as freshwater eutrophication or terrestrial acidification in low-GWP technologies. The findings reveal that technologies with the lowest GWP presently come at a higher cost, ranging from approximately $4 to $9 per kilogram of hydrogen, as opposed to the prevailing fossil fuel-based hydrogen production technologies, which cost roughly $1 to $2 per kilogram of hydrogen. © 2025 selection and editorial matter, Mohammad Reza Rahimpour, Mohammad Amin Makarem and Parvin Kiani.
Currently, syngas and H2 are two of the most important intermediates and raw materials that produce high-value products and are considered as energy carriers in the future. Steam reforming of natural gas (methane) is the most widely used technology in the industries for the production of syngas and H2. The promising applications of H2 and syngas in different processes, especially as clean energy sources, have attracted the attention of many researchers. Simulation and modeling of chemical processes could help to improve understanding of the whole process and increase their efficiency by the optimization of the operating conditions. In addition, using mathematical tools to describe chemical processes could save time and money. Regarding these benefits, it is necessary to evaluate the conventional processes of H2 and syngas production from natural gas from the viewpoint of modeling and simulation. In this chapter, due to the importance of H2 and syngas in chemical processes, the methane steam reforming in fixed-bed, fluidized-bed, and autothermal reformers has been investigated with the approach of equipment modeling and simulation. Different types of models and their simplifying assumptions are also discussed in detail. © 2024 Elsevier Inc. All rights reserved.
Hydrogen, which can be generated from several sources, has the potential to be a clean energy carrier, producing only water after combustion. Around half of the world's hydrogen production capacity is created each year, mostly from fossil fuels using natural gas reforming techniques such as steam reforming, partial oxidation, dry reforming, autothermal reforming, and trireforming. The most established, often employed, and widely utilized technique for producing hydrogen is methane steam reforming. In fixed-bed reactors, this reaction is frequently carried out. There are several separation processes to separate hydrogen with desired purity. Membrane reactors are merely single-stage devices that allow the reaction and separation of one or more products simultaneously. They are an excellent alternative to fixed-bed reactors. Membrane reactors have been investigated as a novel technique for the intensification of natural gas reforming processes to produce pure hydrogen. Mathematical modeling of membrane reactors is critical in selecting design and operational parameters to improve reactor performance. This review chapter summarizes and compares packed- and fluidized-bed membrane reformers for hydrogen production from natural gas. It includes an overview of the fundamentals of membrane reformers and various types of modeling methodologies, including pseudohomogeneous, heterogeneous, and two-phase models. Furthermore, the impact of operational parameters of methane steam membrane reformer, such as reaction temperature, pressure, residence time, and H2O/CH4 molar ratio, is explored on methane conversion and hydrogen yield. The implications of hydrogen transfer from the reaction side to the permeation side in membrane reformers will be explored, because the influence of this transfer on the efficiency of membrane reformers will be more acceptable than traditional ones. © 2024 Elsevier Inc. All rights reserved.
Energy and Fuels (08870624) 38(4)pp. 3221-3237
Recently, CO2 capture has been given attention as an effective way to mitigate the impacts of global warming. However, CO2 capture through adsorption technology is restricted by the cost of energy consumption, and the optimization of this technology deserves to be noted. Rigorous mathematical models along with optimization algorithms result in significant savings in both time and cost of the experiment. In this paper, a purposeful optimization for the rapid temperature swing adsorption (RTSA) cycle using amino silica hollow fiber adsorbents was presented to evaluate the competitiveness of this fledgling technology with other adsorption methods. Achieving the highest purity and recovery as two conflicting objectives and obtaining the highest process productivity at the lowest energy consumption were two demands for the applicants, which were optimized through a hybrid model of the multiobjective differential evolution (MODE) algorithm and Technique for the Order of Preference by Similarity to Ideal Solution (TOPSIS) decision-making method. The key operating parameters containing water velocity (0.1-2 m/s), feed and purge gas velocity (0.1-6 m/s), and cooling (15-40 °C) and heating (80-120 °C) temperatures, as well as adsorption (50-500 s), heating (100-250 s), and sweeping (20-150 s) step times, were chosen as decision variables to find the optimal operating point from the Pareto set. A summary of performance comparison between the amino silica hollow fiber-based RTSA cycle and other CO2 capture technologies available in the literature showed that this cycle with purity and recovery above 80% operates below current international standards. In addition, the energy consumption in this system was higher than other technologies due to the high heat of adsorption of the amino silica adsorbent, which can be overcome to this challenge by choosing a suitable adsorbent or configuration. © 2024 American Chemical Society.
Colloids and Surfaces A: Physicochemical and Engineering Aspects (18734359) 687
Objectives: Epoxy adhesives are advanced materials, but suffer from high brittleness and low toughness due to their high crosslinking degree, which limits their service life in structural applications. The lack of appropriate thermal stability at high temperatures is another constraint of epoxy adhesives. The main aim of this research was to increase the thermal stability and toughness of epoxy adhesives using phenolic resin, zinc oxide (ZnO) nanoparticles, and poly (butyl acrylate-block-styrene) copolymer as a toughening agent. Furthermore, the mechanical properties of epoxy adhesives were predicted by designing two feed-forward multilayer perceptron (MLP) networks. Methods: Epoxy adhesives with different contents of phenolic resin (10, 20, and 30 phr), copolymer (1.25, 2.5, and 3.75 phr), and ZnO (0.5, 1, 2, and 5 phr) nanoparticles were synthesized under mechanical mixing by using xylene as solvent. Then, the epoxy adhesive samples for tensile and lap shear tests were cured at room temperature for 7 and 2 days, respectively. The mechanical properties of adhesive samples were measured by tensile and lap shear tests. The thermal stability of the epoxy adhesive samples was investigated by thermogravimetric analysis (TGA). The kinetics of the curing reaction of the optimum epoxy adhesive samples was also studied by differential scanning calorimetry (DSC). Results: The toughness of epoxy adhesive containing 10 phr phenolic, 2.5 phr block copolymer, and 2 phr ZnO nanoparticles increased by 20%, and shear strength by 99% compared to pure epoxy adhesive, notifying a significant synergistic effect. The TGA results showed that all three mentioned additives have increased the thermal stability of pure epoxy. The highest thermal stability was observed for epoxy adhesive containing 2.5 phr block copolymer and 2 phr ZnO nanoparticles. In addition, DSC analysis proved the positive effect of ZnO nanoparticles incorporation and block copolymer on the curing kinetics of epoxy adhesive. Moreover, the predicted tensile strength, tensile modulus, toughness, and shear strength of epoxy adhesives by MLP networks showed a very good consistency between the experimental data and the model predictions (e.g., MRE < 1.1 for lap shear). Significance: In the current study, the artificial neural networks (ANN) results showed that there was very good consistency between the ANN predictions and the experimental data. © 2024 Elsevier B.V.
The process of methane tri-reforming can effectively produce hydrogen and synthesis gas with an adjustable H2/CO molar ratio under minimal environmental impact and optimal energy consumption. This is achieved through a combination of carbon dioxide reforming, steam reforming, and partial oxidation of methane in a single reactor. The process is thoroughly evaluated in this work, including the reactions and their kinetics, the impact of operating conditions on CO2 and CH4 conversion and hydrogen production, and the use of practical catalysts. Different reactor configurations are also compared. Despite the progress made, methane tri-reforming still faces technical challenges and appears to be in its early stages of development. © 2025 selection and editorial matter, Mohammad Reza Rahimpour, Mohammad Amin Makarem and Parvin Kiani.
Renewable and Sustainable Energy Reviews (13640321) 175
Currently, global concerns about greenhouse gas emissions, climate changes, and over-consumption of fossil fuels have drawn human attention to the use of environmentally friendly biofuels and renewable energy sources such as biodiesel. Though biodiesel can serve as an alternative source to fossil diesel fuel, it is quite comparatively expensive to produce. This challenge can be nullified by converting glycerol, a main by-product during biodiesel synthesis, into valuable products such as hydrogen. Catalytic steam reforming of bio-glycerol is one of the potential technologies to address this requirement, which is the main subject of this research. However, this process suffers from energy supply and environmental issues due to CO2 emissions. In an attempt to resolve this problem, an energy self-sufficient approach has been developed to provide the required energy in an eco-friendly way through the combustion of a part of the produced hydrogen. Among the impacts of this novel procedure on environmental and energy resources management, the following can be mentioned: eliminating dependence on hydrocarbon energy resources; non-greenhouse gas emissions; hydrogen production as renewable energy; and syngas production suitable for methanol and GTL synthesis processes. After sensitivity analysis and optimization of thermal efficiency, the highest hydrogen recovery (≅70%) and H2:CO≅2 can be achieved at acceptable glycerol conversion (≅81%) and the lowest level of hydrogen consumption (which is 1/5 of the total produced hydrogen). Furthermore, comparing this process with other conventional hydrogen production technologies showed that it was competitive with other ones in terms of thermal efficiency (≅50%), making it highly promising for commercialization. © 2023 Elsevier Ltd
Syngas, a mixture of CO and H2, is one the most useful intermediates that produces many valuable products. Alcohols are among the most important of these products and include a wide range of chemical compounds from methanol and ethanol to higher carbon alcohols, which can be used as fuel additives, energy carriers, and solvents. These promising applications of alcohols, especially as clean energy sources, have attracted the attention of many researchers. Simulation and modeling of chemical processes could help to improve understanding of the whole process and increase their efficiency by optimization of the operating conditions. In addition, using mathematical tools to describe the chemical processes could save time and money. Regarding these benefits, it is necessary to evaluate the alcohols synthesis process from the viewpoint of modeling and simulation. In this chapter, due to the importance of alcohols in chemical processes, the simulation of alcohols synthesis plant from syngas is investigated with the approach of modeling and simulation of equipment. Different types of reactors and their mathematical models with the corresponding kinetic models are also discussed in detail. © 2023 Elsevier Inc. All rights reserved.
Syngas, a mixture of CO and H2, can be used for many processes such as methanol and Fischer–Tropsch synthesis. It can be produced through several ways such as steam reforming, dry reforming, trireforming, and partial oxidation. Catalytic partial oxidation has some benefits over other methods, for example, lower reaction temperature levels. Different fuels, including light hydrocarbons, high hydrocarbons, oxygenated hydrocarbons, and biofuels, can be used as a feedstock for partial oxidation; however, methane is the favorite. Knowing the reaction pathway, kinetics, and catalyst properties can help further experiments and research studies. This chapter discusses the catalytic partial oxidation of various types of hydrocarbons focusing on methane and its reaction kinetics. A brief review of two categories of catalysts, containing noble and non-noble catalysts, is also presented. © 2023 Elsevier Inc. All rights reserved.
Catalytic reduction of nitrobenzene is the leading technological step in aniline production. The hydrogen required for this stage, is dominantly produced from fossil fuels through reforming processes, which take much energy and emit large amounts of CO2. Biomass-derived glycerol steam reforming is an attractive alternative to traditional reforming to reduce the dependence on hydrocarbon resources and mitigate climate change. This research aims to analyze a mass- and heat-integrated multi-tubular membrane reactor, containing nitrobenzene hydrogenation (exothermic-side) and glycerol steam reforming (endothermic-side) for co-production of aniline and syngas. In this process, hydrogenation reaction acts as a heat source for glycerol reforming, while hydrogen produced in the endothermic-side simultaneously permeates through the membrane, reacts with nitrobenzene to produce aniline and enhances the equilibrium glycerol conversion. Besides, the steam produced in the exothermic-side is continuously recycled to the entrance of the endothermic-side. The role of different parameters on reactor performance is realized using a heterogeneous model. Numerical results show that by adjusting the adequate operating conditions, glycerol and nitrobenzene conversion above 80% and syngas with H2/CO ratio in the range of 2.0–2.5, suitable for Fischer-Tropsch and methanol synthesis processes, can be achieved. In addition, this integrated process is promising in terms of energy saving, environmental pollution mitigation, feasibility and effectiveness for industrial-scale application; however, experimental proof-of-concept is required to ensure the safe operability of this process. © 2021 Elsevier Ltd
Chemical Engineering Journal (13858947) 405
The side reactions play an evident role in the selectivity of propylene in methanol to propylene (MTP) process. Recycling by-products such as C4 and C5 hydrocarbon cuts is an effective way to utilize these hydrocarbons and to improve the propylene selectivity. So, the aim of this study was to present a kinetic model for the MTP process over the H-ZSM-5 (Si/Al = 200) catalyst in the presence of co-reaction of methanol and C4-C5 olefin mixture based on the Langmuir-Hinshelwood theory. This model was established on a comprehensive mechanism including methanol conversion, methylation, cracking, hydrogenation, dehydrogenation, and oligomerization reactions. The Response Surface Methodology based on Central Composite Design was applied to evaluate the impact of C4= (5–16 wt%) and C5= (2–9 wt%) mass fraction, WHSV (1.93–7.73 h−1), and temperature (455–485 °C) on the product distribution. It was found that the co-feeding of C4-C5 olefin mixture with methanol can enhance the propylene selectivity up to 73% by controlling the operating conditions. The excellent agreement between the model prediction and experimental data shows that the proposed kinetic model accurately describes the product distribution, and is applicable to this process. © 2020 Elsevier B.V.
Energy Conversion and Management (01968904) 247
Hydrogen and syngas, as two effective clean fuels, have a considerable stake in the global fuel market. These are dominantly produced from fossil fuels through reforming processes, which lose a large amount of energy and emit numerous amounts of CO2. Bio-renewable glycerol steam reforming is an attractive alternative to traditional reforming for reducing the dependence on hydrocarbon resources and mitigating climate change. This research aims to manage a heat-integrated reactor with three concentric cylinders, containing exothermic-side (methane tri-reforming), endothermic-side (glycerol steam reforming), and permeation-side for co-production of pure hydrogen and syngas. In this process, tri-reforming was used as a heat source to drive the glycerol reforming reaction; hydrogen was continuously permeated through the palladium perm-selective membrane, and at the same time, the effluent gas produced in the endothermic-side was recycled to the exothermic-side as the feedstock to reduce the greenhouse gas emissions. A theoretical study was conducted using a one-dimensional heterogeneous model to realize the role of effective parameters on glycerol and methane conversion as well as hydrogen recovery. Numerical results show that by adjusting the adequate operating conditions, glycerol and methane conversion equal to 100%, hydrogen recovery above 70%, and syngas with H2/CO ratio in the range of 1.8–2.0, compatible with the Fischer-Tropsch and methanol synthesis processes, can be achieved. In addition, this heat-integrated process is promising in terms of energy saving, environmental pollution reduction, feasibility and effectiveness for industrial-scale application; however, experimental proof-of-concept is required to ensure the safe operability of this process. © 2021 Elsevier Ltd
Chemical Engineering and Technology (09307516) 44(3)pp. 417-430
A mathematical model entitled varying-bubble model (V-BM) was adapted to simulate a slurry bubble-column reactor, operating in a churn-turbulent regime, based on an axial-dispersion model. This model was theoretically able to estimate the size of forming bubbles at the sparger, variations of each chemical species and catalyst concentration, pressure drop in both gas and liquid phases, change in size and rising velocity of bubbles, as well as gas holdup and specific gas-liquid interfacial area along the reactor axis. A comparison between the V-BM and single-bubble model (S-BM) indicates that the V-BM is better compatible with the experimental data. The results demonstrate that the contribution of mass transfer is much more than the pressure drop in increasing the size of the bubble along the reactor. © 2021 Wiley-VCH GmbH
International Journal of Hydrogen Energy (03603199) 46(27)pp. 14441-14454
Assessment of the recent research on the side-feeding strategy in the methane tri-reforming reactor, suggests that this procedure can be a beneficial method for producing syngas. In the present study, special attention is given to the length of methane tri-reformer due to its significant effect on the residence time of distributed components, reaction pathways, synthesis gas production, and reactor performance in side-feeding procedures. The optimal design of three types of membrane tri-reforming reactor, containing O-MTR, H-MTR, and C-MTR, in which O2, H2O, and CO2 permeate as the distributed reactants through the micro-porous membrane, respectively, as well as the conventional tri-reformer (MTR) was carried out to produce proper syngas for methanol and gas-to-liquid (GTL) units. The results show that the O-MTR offers the most advantages in terms of CH4 conversion (i.e., 99.98%), H2 yield (i.e., 1.91), and catalyst lifetime due to no formation of hot spot temperature. Additionally, the CH4 conversion and H2 yield in the O-MTR increased by 5% compared to the MTR. However, the length of these reactor structures to produce appropriate syngas for Fischer-Tropsch and methanol synthesis processes was in the following order: MTR < C-MTR ≅ O-MTR < H-MTR. © 2021 Hydrogen Energy Publications LLC
Journal of Cleaner Production (09596526) 324
Currently, ammonia, as a clean and sustainable energy carrier, is intensively synthesized from its elements during the Haber-Bosch technology. This process requires a large amount of energy and emits numerous amounts of carbon dioxide, because hydrogen is dominantly produced from fossil fuels through reforming processes. Biomass-derived glycerol steam reforming is an attractive alternative to traditional reforming for reducing the dependence on hydrocarbon resources and mitigating climate change. This research aims to intensify a heat-integrated process for the co-production of ammonia and syngas from glycerol valorization. In this process, glycerol reforming continuously provides hydrogen needed for ammonia synthesis, and the liquid glycerol is simultaneously vaporized by heat generated from ammonia synthesis. Methane tri-reforming acts as a heat source to drive glycerol reforming; at the same time, the effluent gas produced through glycerol reforming is recycled to the tri-reforming side to reduce the greenhouse gas emissions. The role of different parameters on the process performance is identified by a one-dimensional heterogeneous model. Numerical results show that by adjusting the adequate operating conditions, glycerol and methane conversion >95%, nitrogen conversion >25%, glycerol dryness fraction = 1.0, and syngas with hydrogen to carbon monoxide ratio above 2.0, suitable for the Fischer-Tropsch and methanol synthesis processes, can be achieved. In addition, this heat-integrated intensified process is promising in terms of energy saving, environmental pollution mitigation, feasibility and effectiveness for industrial-scale application; however, experimental proof-of-concept is required to ensure the safe operability of this process. © 2021 Elsevier Ltd
Journal of the Taiwan Institute of Chemical Engineers (18761070) 113pp. 302-314
In recent years, increasing demand for methanol, as a clean alternative to fossil fuels, necessitates analyzing the methanol synthesis reactor in terms of econometrics, methanol production, and energy efficiency. So, the aim of this work was to compare three kinds of industrial methanol synthesis reactor based on implemented cooling technologies, namely direct-cooling reactor (DCR), quench-cooling reactor (QCR), and indirect-cooling reactor (ICR) under the same feed-flow rate and catalyst weight. The performance of these reactors was evaluated in terms of energy efficiency and methanol yield under optimal conditions obtained through an economic-optimization. To identify decision variables for optimization procedure, a one-dimensional heterogeneous model was established to investigate the impact of different variables on the methanol yield. The results show that the DCR had the most profit value (i.e., 249,697 US$/day) and the highest methanol yield (i.e., 0.455) compared to other reactors. In addition, although no excess energy was required to provide products in all configurations due to the arrangement of equipment suggested for these processes, boiling-water was used to cool the catalyst-bed of DCR. In general, these configurations could be sorted from the most desirable one to the least in the following order: DCR > 5-bed ICR > 5-bed QCR. © 2020 Taiwan Institute of Chemical Engineers
International Journal of Hydrogen Energy (03603199) 45(30)pp. 15239-15253
Methane tri-reforming is an efficient route to produce syngas. Distributing one component through a micro-porous membrane, namely side-feeding procedure, is an effective method for controlling reactions pathway and achieving the higher performance in membrane reactors. More recently, Alipour-Dehkordi and Khademi (2019) suggested a feasible and beneficial membrane multi-tubular reactor with O2, H2O or CO2 side-feeding policy to describe the methane tri-reforming for producing a suitable syngas for the methanol and dimethyl ether direct synthesis processes. To complete the previous research, a theoretical study was presented to detect the role of effective parameters, including molar flow rate of feed components, membrane thickness, shell-side pressure, and inlet gas temperature on the H2/CO ratio, CH4 conversion, H2 yield, and CO2 conversion. Several results were observed, however one of the most attractive results was to achieve CO2 conversion up to 40% in these configurations by controlling the influencing parameters (compared to CO2 conversion in the conventional tri-reformer (i.e., 11.5%)); that would be favorable for the environment. © 2020 Hydrogen Energy Publications LLC
Scientia Iranica (23453605) 26(6)pp. 3401-3414
In recent years, biofuels have attracted considerable attention as a renewable and clean source of energy and have been playing the role of suitable alternatives to fossil fuels. One of the most attractive types of biofuels is Acetone-Butanol-Ethanol (ABE), which is produced in a batch fermentation process by the anaerobic bacterium Clostridium acetobutylicum and sugar-based substrate as feedstock. In this paper, the optimization of this process was carried out according to a bi-objective function. A hybrid model of Multi-Objective Differential Evolution (MODE) algorithm and distinguished decision-making methods, namely linear programming technique for multidimensional analysis of preference (LINMAP), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and Shannon's entropy, were applied to find the final optimal operating point. The initial concentration of substrate and the final operating time of the process were selected as decision variables to maximize the two main objectives in terms of solvent yield and productivity. A Pareto optimal set presents a wide range of optimal operating points, and a proper operating condition can be selected based on the necessities of the applicant. The best optimal point obtained by TOPSIS, according to the lowest value of deviation index, was also compared with the results of the economy-based optimization. (C) 2019 Sharif University of Technology. All rights reserved.
International Journal of Hydrogen Energy (03603199) 44(60)pp. 32066-32079
A one-dimensional heterogeneous model for four configurations of a reactor, three micro-porous membrane reactors with O2 (O-MMTR), CO2 (C-MMTR) or H2O (H-MMTR) side-feeding strategy and one traditional reactor (i.e., multi-tubular fixed-bed reactor (MTR)), was developed to explain tri-reforming of methane to produce syngas. Effect of various side-feeding strategies on reactor performance containing CH4 and CO2 conversion, H2/CO ratio, and H2 yield was investigated under the same condition and then described by chemical species and temperature profiles. It was found that use of side-feeding strategies could be feasible, beneficial, and flexible in terms of change in membrane thickness and shell-side pressure for syngas production with H2/CO = 2 which is proper for methanol and Fischer-Tropsch process, and = 1.2 which is suitable for DME direct synthesis. However, the syngas produced by the MTR is only appropriate for the methanol and Fischer-Tropsch synthesis under the base case conditions. Also, the results show that the micro-porous membrane reactors have higher CO2 conversion, based on the H2/CO = 1.2; so these strategies are more environmentally friendly compared to the traditional reactor. © 2019 Hydrogen Energy Publications LLC
Chemical Engineering Research and Design (17443563) 128pp. 306-317
In this study, simulation and optimization of ammonia synthesis reactor based on the implemented cooling methods was presented in three cases: internal direct cooling reactor (IDCR), adiabatic quench cooling reactor (AQCR), and adiabatic indirect cooling reactor (AICR). A one-dimensional pseudo-homogeneous model was developed to investigate the effect of various parameters on maximum N2 conversion at the outlet of IDCR, 2-bed AQCR and 2-bed AICR. Differential evolution algorithm was applied to optimize three types of ammonia synthesis reactor, considering N2 conversion as the main objective. A comparison between IDCR, 2/3/4-bed AQCR and 2/3/4-bed AICR was carried out under the optimal operating conditions by considering the same catalyst volume, operating pressure and feed mass flow rate for all three types of reactor. The optimization results show that a maximum conversion of 0.26 was achieved in 3-bed AQCR, in which the temperature of feed gas to the first bed was 635 K, dimensionless lengths of each bed were 0.13, 0.25 and 0.62, and fractions of total feed flow rate quenching from the first to end bed were 0.2, 0.26 and 0.54, respectively. The optimum value of N2 conversion was found 0.3 in IDCR at the gas temperature to the cooling tube of 495 K. In 3-bed AICR, the highest conversion of 0.3 was determined at temperature of inlet gas to each bed, 696 K, and dimensionless length of each bed, 0.33. Generally, IDCR, 3-bed AICR and 3-bed AQCR were suggested as ammonia synthesis reactor configurations from the most favorable to the least favorable. © 2017 Institution of Chemical Engineers
Fatemeh hosseini, S. ,
Reza talaie, M. ,
Aghamiri, S. ,
Khademi, M.H. ,
Gholami, M. ,
Nasr esfahany, M. Separation and Purification Technology (13835866) 183pp. 181-193
CO2 capture from power plant emissions has posed a great challenge in recent decades. The key factor to respond to such a challenge is to develop a separation process consuming less energy, but producing high purity and recovery compared to the available commercial technologies such as amine absorption. Adsorption process is one of the promising leads to achieve this goal. However, it suffers from the large time period required for the regeneration step. One remedy to overcome this problem is employing Rapid Temperature Swing Adsorption (RTSA). In this study, a two dimensional mathematical model of a RTSA process was developed. A sensitivity analysis was also carried out to determine how different transport parameters and simplifying assumptions influence the calculated breakthrough curve. It was concluded that the external and inter-particle mass transfer resistances were negligible. Also, the effects of the key operating variables such as water velocity in the adsorption and desorption steps (0.01–1 m/s), gas velocity (0.5–5 m/s), adsorption time period (40–200 s), adsorption temperature (5–40 °C), desorption temperature (80–120 °C), and hollow fiber thickness (80–680 µm) on RTSA performance were investigated. The RTSA performance was analyzed in terms of recovery, purity, productivity, the amount of separated pure carbon dioxide in 24 h, and specific energy consumption. The following conclusions were drawn for the base-case scenario: (1) the best thickness of the hollow fiber is 260 µm in which purity, recovery, and the amount of separated pure CO2 are at the maximum values (2) a decrease in adsorption step period time tends to an increase in the productivity and recovery, e.g. the productivity and recovery decrease by half if the adsorption step continues after reaching breakthrough time up to fully saturation state, (3) increasing the gas velocity leads to increasing the productivity and decreasing the recovery with the appropriate value of 2.7 m/s, (4) the water velocity in the adsorption and desorption steps were selected 0.4 m/s, and (5) higher adsorption temperature and desorption temperature resulting in less specific energy consumption. © 2017 Elsevier B.V.
Scientia Iranica (23453605) 24(3)pp. 1253-1263
The present work aims to employ Differential Evolution (DE) algorithm to optimize ethylene oxychlorination process to produce 1,2-dichloroethane in a fluidized bed reactor as a feedstock of PVC production. A steady-state reactor model, based on twophase theory of fluidization, was developed to investigate the effects of various parameters on C2H4 and HCl conversions. The model's results were compared favorably with the industrial data obtained from a pilot plant working in Italy. The feed temperature, pressure, HCl and O2 molar flow rates, and cooling medium temperature were selected as decision variables to minimize the objective function subject to the environmental constraints. The highest performance was found at HCl/C2H4 and O2/C2H4 molar ratios of 2 and 0.55, respectively; feed and cooling medium temperatures of 440 and 360 K, respectively; pressure of 367.6 kPa. The results show a decrease of 20°C in the feed temperature, which leads to saving energy and reducing the size of the pre-heater. © 2017 Sharif University of Technology. All rights reserved.
Lashkarbolooki, M. ,
Hezave, A.Z. ,
Bayat, M. ,
Khademi, M.H. ,
Vaferi, B. Journal of Theoretical and Computational Chemistry (17936888) 15(8)
Thermal conductivity is one of the most important properties of materials especially liquids. Thermal conductivity is highly interesting since it is the main parameter required for most heat-transfer calculations or design of industrial equipments such as heat exchangers. Unfortunately, thermal conductivity is extremely hard to be experimentally measured due to some operational issues which shifted the researchers' interest toward proposing a correlation to predict this property. In the light of this limitation, in the current study, a four-parameter correlation based on critical temperature (Tc), critical pressure (Pc) and acentric factor (ω) of substances is proposed to predict thermal conductivity of liquids. In this way, 956 experimental data points collected from previously published literatures were divided into two different subsets, namely training and testing subsets, in the first stage and then used to find the optimum values of fitting parameters of the proposed correlation. Based on the obtained results of error analysis, it can be concluded that the proposed correlation has capability of both extrapolating and correlating the thermal conductivity of liquids. © 2016 World Scientific Publishing Company.
Frontiers in Heat and Mass Transfer (21518629) 7(1)
An integral energy equation model is used to calculate the heat transfer coefficient/Nusselt number, thermal boundary layer thickness and temperature distribution in the turbulent boundary layer for forced convection over a smooth flat plate. The proposed model is based on two polynomial temperature profiles in a thermal laminar sublayer as well as in a fully developed boundary layer and two integral energy equations. The performance of this new model is compared with the most commonly used semi-empirical correlations and the complex established models such as k-ε, k- ω, RSM, and a good agreement is achieved. © 2016, Global Digital Central. All rights reserved.
Chemical Engineering Communications (00986445) 199(7)pp. 889-911
Coupling energy-intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the capital cost of the reactors. In this study, a steady-state heterogeneous model for a novel thermally coupled reactor, containing methanol synthesis reactions and cyclohexane dehydrogenation, was developed. This heat exchanger reactor consists of two fixed beds separated by a wall, where heat is transferred across the surface of the tube from the exothermic into the endothermic side. The co-current mode is investigated, and the simulation results are compared with corresponding data for an industrial methanol fixed bed reactor operated at the same feed conditions. The results show that although methanol productivity in the thermally coupled reactor is not higher than that in the conventional methanol reactor, benzene is also produced as an additional valuable product in a favorable manner, and autothermality is achieved within the reactor. This novel configuration can increase the methanol synthesis temperature at the first part of the reactor for higher process rates and then reduce the temperature at the second part of reactor for increasing thermodynamic equilibrium; those are two key issues in methanol reactor configurations. The influence of inlet temperature, molar flow rate, and shell diameter of the endothermic stream on reactor behavior is investigated. The results suggest that coupling of these reactions in co-current mode could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © Taylor & Francis Group, LLC.
Fluid Phase Equilibria (03783812) 313pp. 140-147
The main goal of this study was to measure the solubility of mefenamic acid in supercritical carbon dioxide (SC-CO2) at pressures and temperatures range of 16-40MPa and 308.15, 318.15, 328.15 and 338.15K, respectively. The obtained results revealed that the mole fractions were varied in the range of 8.31×10-5-5.98×10-3 under the different conditions. The obtained results were correlated with four empirical correlations including Chrastil, Mendez-Santiago-Teja (MST), Bartle and Kumar and Johnston (K-J) models. The optimized parameters of these correlations were obtained by the graphical regression. The calculated results show a good consistency between the measured and calculated solubilities for Chrastil, MST, Bartle and Kumar and Johnston models with average absolute relative deviation percent (AARD%) of 5.84%, 3.93%, 4.79%, and 5.20%, respectively. In addition, experimental results were modeled with two equations of state including the Esmaeilzadeh-Roshanfekr (ER) and Peng-Robinson (PR) EoSs which their binary interaction parameters, kij and lij, were optimized by the differential evolution (DE) method. DE is a very simple population based stochastic function minimizer which is very powerful at the same time. The estimated solubilities show maximum AARD% of 21.25% and 30.56% and minimum AARD% of 3.54% and 6.81% were found for the ER and PR-EOS's, respectively. © 2011 Elsevier B.V.
Chemical Engineering and Processing - Process Intensification (02552701) 50(1)pp. 113-123
This paper presents a study on optimization of DME synthesis and cyclohexane dehydrogenation in a thermally coupled reactor. A steady-state heterogeneous model has been performed in order to evaluate the optimal operating conditions and enhancement of DME and benzene production. In this work, the catalytic methanol dehydration to DME is coupled with the catalytic dehydrogenation of cyclohexane to benzene in a heat exchanger reactor formed of two fixed beds separated by a wall, where heat is transferred across the surface of tube. The optimization results are compared with corresponding predictions for a conventional (industrial) methanol dehydration adiabatic reactor operated at the same feed conditions. The differential evolution (DE), an exceptionally simple evolution strategy, is applied to optimize thermally recuperative coupled reactor considering DME and benzene mole fractions as the main objectives. The simulation results have been shown that there are optimum values of initial molar flow rate and inlet temperature of exothermic and endothermic sides to maximize the objective function. The results suggest that optimal coupling of these reactions could be feasible and beneficial and improves the thermal efficiency of process. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2010 Elsevier B.V.
International Journal of Hydrogen Energy (03603199) 36(1)pp. 299-310
Coupling energy intensive endothermic reaction systems with suitable exothermic reactions followed by hydrogen permeation through the Pd/Ag membrane improves the thermal efficiency of processes, achieving the autothermality within the reactor, reduces the size of reactors, produces the pure hydrogen, and achieving a multiple reactants multiple products configuration. This paper focuses on optimization of hydrogen, dimethyl ether (DME) and benzene production in a membrane thermally coupled reactor. A steady-state heterogeneous mathematical model that is composed of three sides is developed to predict the performance of this novel configuration reactor. The catalytic methanol dehydration to DME takes place in the exothermic side that supplies the necessary heat for the catalytic dehydrogenation of cyclohexane to benzene reaction in the endothermic side. Selective permeation of hydrogen through the Pd/Ag membrane is achieved by co-current flow of sweep gas through the permeation side. This novel configuration can decrease the temperature of methanol dehydration reaction in the second half of the reactor and shift the thermodynamic equilibrium. The differential evolution (DE), an exceptionally simple evolution strategy, is applied to optimize membrane thermally recuperative coupled reactor considering the summation of methanol and cyclohexane conversions and dimensionless hydrogen recovery yield as the main objectives. The simulation results have been shown that there are optimum values of initial molar flow rate of exothermic and endothermic sides and inlet temperature of exothermic, endothermic and permeation sides to maximize the objective function. The optimization method has enhanced the methanol conversion by 2.76%. The optimization results are compared with corresponding predictions for a conventional (industrial) methanol dehydration adiabatic reactor operated at the same feed conditions. The results suggest that coupling of these reactions could be feasible and beneficial. An experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Industrial and Engineering Chemistry Research (15205045) 50(21)pp. 12092-12102
Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes, achieving the autothermality within the reactor, reducing the size of the reactors, and achieving a multiple reactants-multiple products configuration. In this study, a dynamic heterogeneous model for a novel thermally coupled reactor-containing methanol synthesis reactions and cyclohexane dehydrogenation-is developed to consider the startup and transient response of the system. This heat-exchanger reactor consists of two fixed beds separated by a wall, where heat is transferred across the surface of tube from the exothermic side to the endothermic side. The proposed model was validated against conventional methanol synthesis reactor, and a good agreement was achieved. Dynamic simulation results for the co-current mode have been investigated to present the response of the reactor outlet temperature, methanol yield, and cyclohexane conversion in the cases of a step change in the initial molar flow rate and inlet temperature of both sides. The challenges posed by the transient operation of thermally coupled reactor are identified to avoid severe issues that can arise in the course of operating the reactor (such as reactor extinction). The results suggest that control of this coupled reactor could be feasible and beneficial. © 2011 American Chemical Society.
Industrial and Engineering Chemistry Research (15205045) 50(7)pp. 4050-4056
In this study, a multilayer perceptron (MLP) network is proposed to predict the thermal conductivity (Î) of an electrolyte solution at atmospheric pressure, over a wide range of temperatures (T) and concentrations (x) based on the molecular weight (M) and number of electrons (n) of the solute. The accuracy of the proposed artificial neural network (ANN) was evaluated through performing a regression analysis on the predicted and experimental values of various aqueous solutions, some of which were not used in the network training. The comparison of the developed MLP network to other correlations recommended in the literature indicates that the proposed neural network outperforms other alternative methods, with respect to accuracy as well as extrapolation capabilities. Besides, others' conductivity correlations are usually suggested for a specific electrolyte solution and a limited range of temperatures and concentrations, while such limitations do not exist for the proposed MLP network. © 2011 American Chemical Society.
Chemical Engineering Science (00092509) 65(23)pp. 6206-6214
In this research, the conditions at which a thermally coupled reactor - containing the Fischer-Tropsch synthesis reactions and the dehydrogenation of cyclohexane - operates have been optimized using differential evolution (DE) method. The proposed reactor is a heat exchanger reactor consists of two fixed bed of catalysts separated by the tube wall with the ability to transfer the produced heat from the exothermic side to the endothermic side. This system can perform the exothermic Fischer-Tropsch (F-T) reactions and the endothermic reaction of cyclohexane dehydrogenation to benzene simultaneously which can save energy and improve the reactions' thermal efficiency. The objective of the research is to optimize the operating conditions to maximize the gasoline (C5+) production yield in the reactor's outlet as a desired product. The temperature distribution limit along the reactor to prevent the quick deactivation of the catalysts by sintering at both sides has been considered in the optimization process. The optimization results show a desirable progress compared with the conventional single stage reactor. Optimal inlet molar flow rate and inlet temperature of exothermic and endothermic sides and pressure of exothermic side have been calculated within the practicable range of temperature and pressure for both sides. © 2010 Elsevier Ltd.
Chemometrics and Intelligent Laboratory Systems (01697439) 104(2)pp. 195-204
In this study, a feedforward three-layer neural network is developed to predict binary diffusion coefficient (DAB) of gases at atmospheric pressure over a wide range of temperatures based on the critical temperature (Tc), critical volume (Vc) and molecular weight (M) of each component in the binary mixture. The accuracy of the method is evaluated through a test data set not used in the training stage of the network. Furthermore, the performance of the neural network model is compared with that of well known correlations suggested in the literature. The results of this comparison show that our developed method outperforms other correlations, with respect to accuracy as well as extrapolation capabilities. © 2010 Elsevier B.V.
Chemical Engineering and Technology (09307516) 33(6)pp. 867-877
A simple model is presented for turbulent momentum transfer on a flat plate. The proposed model is based on some polynomial velocity profiles in a laminar sublayer as well as in a fully developed boundary layer and two integral boundary layer equations. The model could be used for the calculation of boundary layer thickness, velocity profile and skin friction factor on the flat plate. The calculated results are in very good agreement with other proposed empirical correlations. © 2010 WILEY-VCH Verlag GmbH & Co.
International Journal of Hydrogen Energy (03603199) 35(5)pp. 1936-1950
In this work a novel reactor configuration has been proposed for simultaneous methanol synthesis, cyclohexane dehydrogenation and hydrogen production. This reactor configuration is a membrane thermally coupled reactor which is composed of three sides for methanol synthesis, cyclohexane dehydrogenation and hydrogen production. Methanol synthesis takes place in the exothermic side that supplies the necessary heat for the endothermic dehydrogenation of cyclohexane reaction. Selective permeation of hydrogen through the Pd/Ag membrane is achieved by co-current flow of sweep gas through the permeation side. A steady-state heterogeneous model of the two fixed beds predicts the performance of this configuration. A theoretical investigation has been performed in order to evaluate the optimal operating conditions and enhancement of methanol, benzene and hydrogen production in a membrane thermally coupled reactor. The co-current mode is investigated and the optimization results are compared with corresponding predictions for a conventional (industrial) methanol fixed bed reactor operated at the same feed conditions. The differential evolution (DE), an exceptionally simple evolution strategy, is applied to optimize this reactor considering the mole fractions of methanol, benzene and hydrogen in permeation side as the main objectives. The simulation results have been shown that there are optimum values of initial molar flow rate of exothermic and endothermic stream, inlet temperature of exothermic, endothermic and permeation sides, and inlet pressure of exothermic side to maximize the objective function. The simulation results show that the methanol mole fraction in output of reactor is increased by 16.3% and hydrogen recovery in permeation side is 2.71 yields. The results suggest that optimal coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2009.
Industrial and Engineering Chemistry Research (15205045) 49(10)pp. 4633-4643
Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the size of reactors. One type of reactor suitable for such a type of coupling is the recuperative reactor. In this work, the catalytic methanol dehydration to dimethyl ether (DME) is coupled with the catalytic dehydrogenation of cyclohexane to benzene in a simulated integrated reactor formed of two fixed beds separated by a wall, where heat is transferred across the surface of tube. A steady state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The cocurrent mode is investigated, and the simulation results are compared with corresponding predictions for an industrial adiabatic methanol dehydration fixed-bed reactor operated at the same feed conditions. In this coupled reactor, benzene and hydrogen are also produced as additional valuable products in a favorable manner and autothermality is achieved within the reactor. This novel configuration can decrease the temperature of methanol dehydration reaction in the second half of the reactor and shift the thermodynamic equilibrium. Therefore, the methanol conversion and DME mole fraction increase by 1.82% and 1.6%, respectively. The influence of inlet temperature and the molar flow rate of exothermic and endothermic stream on reactor behavior is investigated. The results suggest that coupling of these reactions could be feasible and beneficial. An experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2010 American Chemical Society.
International Journal of Hydrogen Energy (03603199) 34(12)pp. 5091-5107
Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improve the thermal efficiency of processes and reduce the size of the reactors. One type of reactor suitable for such a type of coupling is the heat-exchanger reactor. In this work, a distributed mathematical model for thermally coupled membrane reactor that is composed of three sides is developed for methanol and benzene synthesis. Methanol synthesis takes place in the exothermic side and supplies the necessary heat for the endothermic dehydrogenation of cyclohexane reaction. Selective permeation of hydrogen through the Pd/Ag membrane is achieved by co-current flow of sweep gas through the permeation side. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The co-current mode is investigated and the simulation results are compared with corresponding predictions for an industrial methanol fixed-bed reactor operated at the same feed conditions. The results show that although methanol productivity is the same as conventional methanol reactor, but benzene is also produced as an additional valuable product in a favorable manner, and auto-thermal conditions are achieved within the both reactors and also pure hydrogen is produced in permeation side. This novel configuration can increase the rate of methanol synthesis reaction and shift the thermodynamics equilibrium. The performance of the reactor is numerically investigated for various key operating variables such as inlet temperatures, molar flow rates of exothermic and endothermic streams, membrane thickness and sweep gas flow rate. The reactor performance is analyzed based on methanol yield, cyclohexane conversion and hydrogen recovery yield. The results suggest that coupling of these reactions in the presence of membrane could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2009 International Association for Hydrogen Energy.
Khademi, M.H. ,
Hezave, A.Z. ,
Jahanmiri a., A. ,
Fathikalajahi j., J. Journal of Chemical and Engineering Data (00219568) 54(3)pp. 690-700
In this paper, a new correlation for prediction of the ratio of critical temperature to critical pressure has been developed in terms of heat capacity at 298.15 K, which is readily available for many compounds. The correlation has been applied for more than 100 low to medium size compounds. The results of these estimations validate the generalization of this correlation. The comparison between predicted and available experimental data shows an absolute relative error of 4.69 %. The results show that the accuracy of the proposed correlation is similar to the methods of Constantinou and Gani,7 Ambrose,2,3 and Joback5 for various types of compounds. © 2009 American Chemical Society.
International Journal of Thermal Sciences (12900729) 48(6)pp. 1094-1101
A feedforward three-layer neural network is proposed to predict conductivity (k) of pure gases at atmospheric pressure and a wide range of temperatures based on their critical temperature (Tc), critical pressure (Pc) and molecular weight (MW). The accuracy of the method is evaluated and tested by its application to experimental conductivities of various gases which some of them are not used in the network training. Furthermore, the performance of the proposed technique is compared with that of conventional recommended models in the literature. The results of this comparison show that the proposed neural network outperforms other alternative methods, with respect to accuracy as well as extrapolation capabilities. Besides, conventional conductivity correlations are usually used for a limited range of temperature and components while the network method is able to cover a wide range of temperatures and substances. © 2008 Elsevier Masson SAS. All rights reserved.
International Journal of Hydrogen Energy (03603199) 34(16)pp. 6930-6944
This paper presents a study on optimization of a methanol synthesis and cyclohexane dehydrogenation in a thermally coupled reactor. A theoretical investigation has been performed in order to evaluate the optimal operating conditions and enhancement of methanol and benzene production in a thermally coupled reactor. Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the size of the reactors. In this work, the catalytic methanol synthesis is coupled with the catalytic dehydrogenation of cyclohexane to benzene in a heat exchanger reactor formed of two fixed beds separated by a wall, where heat is transferred across the surface of tube. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The co-current mode is investigated and the optimization results are compared with corresponding predictions for a conventional (industrial) methanol fixed bed reactor operated at the same feed conditions. The differential evolution (DE), an exceptionally simple evolution strategy, is applied to optimize methanol and benzene synthesis coupled reactor considering methanol and benzene mole fractions as the main objectives. The simulation results have been shown that there are optimum values of initial molar flow rate of endothermic stream and inlet temperature of exothermic and endothermic sides to maximize the objective function. The optimization method has enhanced the methanol mole fraction by 3.67%. The results suggest that optimal coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. © 2009 International Association for Hydrogen Energy.
Chemical Engineering and Processing - Process Intensification (02552701) 48(1)pp. 339-347
This study presents the steady-state simulation and optimization of a six-effect evaporator and the provision of its relevant software package. In this investigation, the modeling equations of each of the existing building blocks are written in a steady-state conditions. These equations have been used for simulation and process optimization of the entire vaporizing unit while exercising the simplifying assumptions. The effect of different parameters on consumed steam produced distilled water and GOR is presented. The feed mass flow rate, condenser pressure and operating time are optimized for this system. The simulation results are good agreement with design data. © 2008 Elsevier B.V. All rights reserved.
Journal of Chemical and Engineering Data (00219568) 54(3)pp. 922-932
Prediction of gas thermal conductivity is crucial in the heat transfer process. In this article, we develop a novel method to estimate conductivities of binary gaseous mixtures at atmospheric pressure. The method is a neural network scheme consisting of two consecutive multilayer perceptrons (MLPs). The first MLP estimates pure component conductivities as a function of critical temperature, critical pressure, molecular weight, and temperature. The conductivities calculated in the first MLP as well as molecular weights of both compounds and mole fraction of the light components are fed to the second MLP to predict the thermal conductivity of the mixture. The proposed model was trained and tested through a large set of experimental data over wide ranges of temperatures, compositions, and substances. Comparing the test and training results indicates that the accuracy of the neural model is remarkably better than other alternative methods proposed in the literature. Conventional conductivity correlations require more input parameters which are not available for many gases. Also, correlations recommended for pure gas conductivity are usually valid for a particular range of temperature and substances. However, the MLP scheme is able to cover a wide range of temperatures and substances with a few numbers of parameters which are abundant for most gases. © 2009 American Chemical Society.