simulation

Tissue Plasminogen Activator (tPA) is a recombinant protein used to treat blood clotting disorders such as heart strokes, acute myocardial, and pulmonary blockage. The process design of drug production after laboratory culture consists of two sections: reactor and separation. This research aims to investigate the reactor (fermentor) section. The reactor section has three series reactors of different sizes in which tPA cultivation and industrial production are carried out. In this research, first, a base-case simulation of the reactor section was performed by Aspen Batch Plus software, and then a retrofit was presented to remove the bottleneck of the third reactor. 14 days and 15 hours are needed in aiming to achieve the production of 80 Kg tPA/year assuming 50 batch production per year for two completely similar parallel units. The time of each batch process is reduced to about 13 days, 4 hours and 2 minutes in the retrofit design of the process to solve this problem. Reducing the time of the production process helps to increase the annual production up to 82.16 Kg tPA/year. An increase in fixed costs, etc. is inevitable in the modified case because of adding a Heat Exchanger, Hold-up Tank, and Pump.

Perovskite solar cell is the leading generation candidate in the field of photovoltaic industry. The main goal of the current research is performance modelling of direct fiber perovskite solar cell using the classic drift-diffusion model including Poisson's and continuity equations using the finite volume method (FVM). The results of simulation are compared with the one of recent work experimental results and its photovoltaic properties are evaluated. The results of perovskite adsorbent layer optimization showed that the decreasing of radiative recombination coefficient leads to an increase in the open circuit voltage (VOC). In addition, it is inferred that the lessening of the capture cross-section of trapping, total defect density, and thermal voltage velocity of Shockley-Reid-Hall recombination increases the short-circuit current (JSC). Also, reduction of Auger recombination coefficient caused an increase in the filling factor (FF). The electrical properties of perovskite fiber solar cell after optimization including short circuit current (JSC) 15.188 mA/cm, open circuit voltage (VOC) 1.185 V, filling factor (FF) 76.198 %, and power conversion efficiency (PCE) 13.715%, which shows an increase in efficiency compared to the equivalent experimental work.

Millions of dollars of non-renewable capital are burned in flares every year, in the oil and gas industries, which in addition to polluting the air has no income for the industry. In Iran and South Pars region, due to the presence of gas refineries, a considerable amount of gas is burned in the flares. In this research, as a comprehensive study, the technical and economic investigation of the recovery of flare gases has been discussed.

 For this purpose, Aspen Plus software was used to simulate the desired unit in the set of flares of South Pars refinery phases 22-24. The simulation consists of two recovery parts: the flare gases recovery by use of a liquid ring compressor and power generation by the heat from the combustion of the flare gases through the application of the reheat steam Rankine cycle. The profitability of the project includes naphtha cuts and liquefied gas recovered from gases sent to the flare on one hand and power generation in turbines on the other hand.

The effect of the amount of air entering the combustion chamber on the temperature of the exhaust gas was investigated. The amount of air entering the combustion chamber was determined to be 2685 tons per hour in order to obtain supercritical water vapor with a temperature of about 650 ºC and a pressure of 26 kPa in the Rankine cycle. Using the simulation results, the temperature diagram was drawn in terms of entropy, and in addition to the steam phase diagram during the cycle, the steam Rankine cycle diagram was also drawn. The results of this research showed that the designed process will produce 5365 kg/h of naphtha, 179.45 kg/h of LPG, 25903 kW, and 101124 kW power in two separate turbines, and an annual sales income of 24,782,194 $. In addition, it was shown that the investment return period of this process is equal to 2.5 months.

Shale gas, an unconventional natural gas resource abundant in organic matter, has gained significant attention in global natural gas exploration as a crucial supplement and alternative to conventional natural gas sources. Due to higher electrical resistivity of oil traps in conductive sedimentary backgrounds, shale gas reservoirs are ideal targets for geophysical studies to be explored, whereby the Z-axis tipper electromagnetic method (ZTEM) can be employed to simulate and model their geoelectrical responses. The study conducted involved the utilization of an airborne method, a tool that relies on natural source transmitter, to simulate shale gas reservoirs. Initially, geoelectrical models of shallow shale gas reservoirs were constructed for three different simple geological scenarios, followed by the generation of responses through an airborne geophysical survey. The assumed electrical resistivity models were effectively reconstructed by applying an inversion algorithm to the data. This process proved to be successful in accurately representing the physical characteristics of shale gas reservoirs. As a result, this innovative tool offers the capability to rapidly explore vast areas with high potential for shale gas reserves, enabling the identification of valuable targets efficiently. The combination of advanced technology, numerical modeling and geological expertise allows for the expedited discovery of significant resources in the field of shale gas exploration.

Using subcritical water (temperature and pressure of higher than 100 ºC and 1 atm) polarity of water changes into the organic solvents which that can be easily used in extraction of the valuable components from the plant sources. In the present study, simulation of the operation conditions for saponin extraction from the Chubak and using subcritical water was accomplished. Results indicated that by placing the of autoclove in the oven adjusted at temperatures of 120, 140, 160, 180 and 200 ºC, after 120 min the international temperastures of the water inside the autoclove were 107, 124, 144, 161 and 178 ºC, respectively. Saponin extraction was done using water at 130 ºC and 120 min and the result indicated that the water inside of autoclove had temperature of 116 ºC, which that was in subcritical state. The result revealed that lipid content of Chubak was 3% (W/W). Furthermore, extraction results indicated that the foaming height and emulsification capacity of the extracted sample using subcritical water were 2.7 and 1.5 folds higher than those of the extracted sample using water.

In fractured reservoirs under the gravity drainage, the oil transfer between adjacent matrix blocks is one of the main factors in determining the degree of oil recovery. Communication between matrix blocks can occur by forming a liquid bridge between two adjacent matrices. Therefore, in this study, by modeling and simulating in Comsol, we investigated the characteristics of the liquid bridge formed inside the fracture and the dependency of the liquid bridge shape and the pressure difference on the fracture properties such as the fracture aperture, matrix permeability and wettability. Moreover, the initial and boundary conditions in the problem are set such that it can show physically the flow exchange between the matrix and fracture in reservoir conditions. Furthermore, the results of this simulation showed that the liquid bridge throat decreases with the size of the fracture aperture. In addition, this change in the liquid bridge causes the two-phase pressure difference to decrease with the increase of the fracture aperture, and after a critical value (for example, 1.7 mm), it becomes negative. Also, the results showed that as the contact angle increases toward neutral wettability, the more vertically liquid bridge formed and it leads to small changes (40 psi) for two phase pressure difference inside the fracture. In addition, with the increase in rock permeability and more flow entering the fracture, the throat radius of the formed liquid bridge increased from about 0.03 mm to about 0.05 mm, which it is consistent with the published laboratory data. The findings of this research can be used for better understanding how the liquid bridge changes and its effect on the of the two-phase pressure difference, which is a controlling parameter for two phase interface inside fracture.

Physical refining of vegetable oils suggests achieving healthier oils, avoiding excessive oil loss, and reducing production waste. Deacidification or removal of free fatty acids (FFA) is a vital step in the physical refining of vegetable oils. This study aimed to develop a mathematical model that shows the deacidification behavior of cold-pressed camelina oil and lampante olive oil using short-path molecular distillation (SPMD) as a solventless and green technology. Mass conservation balance along with the Langmuir equation were used to describe the evaporation and separation mechanisms. For the oil samples, evaluation of the model prediction capabilities was assessed at different feed flow rates (Q) and evaporation temperatures (ET) while other factors included. feed temperature, vacuum pressure, condensation temperature, and wiper speed were kept constant. To predict vapor pressure, the group contribution method was applied. The model predictions were in reasonable agreement with the experimental data, and showed that higher ET and lower Q led to higher deacidification efficiency. Additionally, the proposed model can be used for determining FFA concentration at different longitudinal parts of the SPMD column.

This paper focuses on the simulation and exergy analysis of flare gas recovery systems and their consuming resources in a gas processing plant, with the aim of minimizing environmental pollution and maximizing energy utilization. During the extraction and processing of oil and gas, significant amounts of unused gases are typically directed to flares, resulting in both environmental pollution and economic waste. Through simulation, it has been determined that approximately 28,700 kg/hour of flare gases can be recovered from the refinery’s flare network, operating at a pressure of 9 bar and a temperature of 25 degrees Celsius. To optimize the consumption of the recovered gases, exergy analysis has been conducted for different consumption scenarios. Two distinct scenarios for the consumption of flare gases are presented. In the first scenario, the recovered gases are compressed to a pressure of 70 bar and injected into the gas sweetening unit of the refinery. Moreover, the calculated exergy efficiency for this scenario is 69%. In the second scenario, the recovered gases are directed to the compressors available in the gas condensate unit. The calculated exergy efficiency for this scenario exceeds 78%. Ultimatly, based on the simulation and exergy analysis results, it is concluded that injecting the recovered flare gases into the compressors of the gas condensate stabilization unit offers the most optimal utilization of the recovered gases. This finding highlights the potential for reducing environmental pollution, minimizing waste, and maximizing the economic resources available in the gas processing plant.

Membrane separation processes are interesting compared with the traditional processes such as distillation, extraction, absorption, etc. due to their superior advantages. Development and simulation of a precise mathematical model for description of phenomena occurred during permeation and transfer of components through membrane could enable one to improve their design, application and operation. In this research a two-dimensional model was used for simulation of CO2 and H2S removal from their mixture with CH4 (as a representative of natural gas sweetening) by absorption on MDEA aqueous solution in polypropylene hollow fiber membrane contactors. The model was solved and simulated using computational fluid dynamic (CFD) in COMSOL software by finite element method. Validation of the simulated CO2 fluxes (0.4 - 2.5 × 10-3 mol/m2.s) through the membrane vs. liquid phase velocity vs. experimental data reveled minimum, average, and maximum errors of 3.45, 9.56, and 17.45 % and those for the gas phase velocity were 2.64, 4.31, and 5.59 %, respectively. The results showed that the gas and liquid absorbent phases’ velocities are the most important affecting factors on the acid gas removal. Also, the liquid phase mass transfer resistance was found determining. With increase in membrane porosity, absorbent concentration and gas phase temperature, the gas outlet’s CO2 concentration were reduced by 45, 68, and 17.5 %, respectively. Increment in the gas and absorbent velocities, reduced and increased the CO2 absorption flux by 15 % and 4.5-fold, respectively. Simultaneous removal of H2S and CO2 reduces the only CO2 removal efficiency by~8 %.

Pigging is one of the conventional processes in the oil and gas industries, which is done in order to remove sediments from pipelines and also perform some non-destructive tests. On the other hand, due to various branches in the main pipeline, there is a possibility of stopping the pig. The right solution is to use mesh caps that not only prevent the pig from getting stuck, but also guarantee the passage of flow through all the main and secondary lines. According to the opinions of technical inspectors, there is no comprehensive information about the presence/absence of these caps in a large number of branches. The industrial radiography lacks the ability to detect the presence and absence of the cap in a fully filled pipe due to the average energy of the emitted beam and its geometrical structure. It is focused on the conceptual design of the nuclear system for investigating the possibility of pigging in the location of pipeline branches in the Monte Carlo environment. Ultimately, the results show the fact that in the situation where the source and the detector are perpendicular to the axis of the main and secondary branches and facing each other, the maximum counting sensitivity and discrimination can be achieved. Moreover, the relative difference of two states with and without the presence of metal grid for two states of filling the pipe with air and oil is equal to 53.8% and 57.1%, respectively.

In this research, the desalination process has been solved by the direct contact membrane distillation process in the flatThis research models the desalination process using a direct contact membrane distillation method in a flat plate configuration with a PTFE membrane. The model employs computational fluid dynamics to solve the differential equations for momentum, heat, and mass transfer. Convective heat transfer in the membrane region is neglected, and mass transfer is described by empirical equations. The simulation results were then validated against available experimental data. Increasing the feed saltwater temperature from 42°C to 78°C led to a significant rise in permeate flux, from 3.59 L.m-2.hr-1 to 18.64 L.m-2.hr-1. The results demonstrates that the distillation flux is directly proportional to the stream velocities and membrane porosity, but inversely proportional to the feed salt concentration, permeate inlet temperature, membrane thickness, pore tortuosity, and membrane conductive heat transfer coefficient.

Tissue plasminogen activator is a recombinant protein for treatment. The main industrial production process of this tissue plasminogen activator mainly includes laboratory growth, fermentation, and separation. This study examines the equipment used in separation process, namely centrifuge, ultrafilter, microfilter, chromatography column, ER column, bottler, freeze dryer and mixing tanks, and the unit operations of this section. Retrofitting such as process debottlenecking (time debottlenecking of freeze dryer) and parallelization of the operations for each batch (1.6 kg product) was carried out and the minimum production time was reduced from 12 to less than 7 days and 23 hours for each batch. A storage tank was also installed to prevent the unit shutdown during the freeze-drying failure. The economic analysis shows the share of the direct costs including raw materials, utilities, etc. is 61.73% per batch and the share of indirect costs including lab charges, marketing, research and development, etc. is 38.27%. Arginine includes 97% of the total $247,000 of raw materials costs. Costs of investment, purchase, equipment installation and essentials needed are estimated to be $39,000,000. This cost is mainly for bottling and freeze-dryer systems.

The fluid catalytic cracking (FCC) process is a cost-effective and reliable route to convert heavy oil fractions into valuable and light products. The riser reactors are commonly commercialized to perform this process. In this study, using a novel modeling-based approach, the design of the FCC riser reactor system is presented based on the gas oil feed with 24.1 kg s-1 mass flow rate. Subsequently, the performance of the designed reactor is examined under various operating conditions. For this purpose, an algorithm is proposed as the design procedure. Initially, the numerical model of the riser reactor is developed and then validated using experimental data including product distribution and outlet temperature. The presented numerical model matches the experimental data of an industrial unit with an average error of 7.52%. Based on the proposed design, the gas oil conversion is 94.32% and the mass fractions of products including diesel, gasoline, LPG, dry gas, and coke are 21.66%, 49.82%, 12.55%, 4.35%, and 5.94%, respectively. The process controllability to operating conditions is also determined based on the sensitivity analysis so that the catalyst-to-oil ratio (COR), feed flow rate, feed temperature, and catalyst temperature can be adjusted to achieve a desirable product distribution.

Counter-current spontaneous imbibition (SI), in which water and oil flow through the same face in opposite directions, is known as one of the most significant oil recovery mechanisms in naturally fractured reservoirs; however, this mechanism has not received much attention. Understanding the dynamic of water-oil displacement during counter-current SI is very challenging because of simultaneous impacts of multiple factors including geometry complexity and heterogeneity of naturally fractured reservoir materials, This study investigates the effects of wettability, fracture aperture and interfacial tension during counter-current SI at pore-scale, the obtained results showed that the wettability of the porous medium changed from a neutral state to a highly hydrophilic state, and it was observed that for contact angles higher than 60 degrees, It was observed that the water mass imbibed into the matrix block varies linearly with time before the water front meets the outlet,  which is captured for the first time in a numerical study. Also, It is revealed that increasing the fracture aperture reduces water breakthrough time and oil recovery, known as “filling fracture” regime, The developed model can be used as a basis for phase-field counter-current simulations and would be useful to study the qualitative and quantitative nature of this phenomenon.

Nowadays, infertility is one of the significant concerns of the World Health Organization (WHO), contributing to a large portion of its annual expenditure. Recent studies reveal that approximately 15% of couples worldwide (more than 50 million couples) encounter infertility problems that are caused by defects in the male or female fertility factors. Although medical advancements have successfully helped a lot of couples with their infertility by assisted reproductive technologies (ART), sperm selection, a crucial stage in ART, has remained challenging. Microfluidic devices are systems that control the movement of minute amounts of fluid using channels in micrometer dimensions, which have a wide range of applications, especially in medicine. This technology can help to enhancethe quality of sorted sperm and be applied to boost our knowledge of sperm behavior and effects of different sperm selection mechanisms within the ART. Here, the efficiency of a microfluidic device having an application in the separation of motile sperm was studied using computational fluid dynamics method and its two-phase-flow module. Laminar flow and Level-set modules were used in this simulation. The mentioned device has three input and three output channels, two channels for sample media and one for buffer. Furthermore, it has a main separation channel, which width becomes wider gradually from the beginning to the end. Thus, output channels have wider width. After simulation, the results were validated using the results of previous experimental and simulation works in this matter. Afterward, to increase the device’s efficiency, the width of the output channel used for the buffer is being altered which prevents the wasting of the motile sperm in buffer. Simulation has shown that increasing the buffer output’s width by 4 times of input fluids channel’s width would cause decreasing the volume fraction of buffer in sample’s outlet to 1%. Therefore, this geometry is presented as the appropriate geometry for separation of motile sperm. In further studies, it is suggested that the last device be manufactured and studied to be validated its efficiency by experiment.

The removal of carbon dioxide due to environmental problems is still of great interest to researchers. In this study, simulation of carbon dioxide removal by absorption four amine base solvents including; monoethanolamine (MEA), diethanolamine (DEA), methyl diethanolamine (MDEA) and aminomethylpropanol (AMP) in a polypropylene hollow fiber membrane reactor is investigated. A comparative study for solvents by multi-physics Comsol software based on fluid dynamics (CFD) calculations is performed. The results showed that the best adsorption rate was obtained by MEA solvent with 88% CO2 absorption rate. The absorption of carbon dioxide by each amine-based solvents in the references is investigated separately. The simulation results are validated separately for each solvent. An acceptable consistency is obtaned between the present simulation data and the results of others given refrences. Finally, as a result of this study, it is shown that the present simulation is powerfully provided suitable and alternative data for carbon dioxide removal by each four traditional amine-based solvents in compare with the available experimental data.

One of the widely used methods to remove acid gas is surface adsorption using solid molecular sieves. The advantages of H2S adsorption with molecular sieves can be seen in reversibility of the process, chemical and thermal stability, no secondary product, and high selectivity of H2S in these adsorbents. Therefore, in this study, Aspen-Adsim software was used to investigate the effect of various parameters on adsorption of H2S on 4A molecular sieve adsorbent. The desired bed is considered vertical and one-dimensional. The results related to the breakthrough curves and saturation time showed that maximum amount of adsorption occurred in early times. As the adsorption time increases, the rate of H2S adsorption decreases. The results of investigating the effect of operating parameters showed that increasing the tower pressure from 90 to 104 bar reduces the output H2S content by 21 ppm. Also, reducing the feed temperature showed significant results on amount of H2S absorption and the reduction of the output H2S content, so that for every one degree of temperature reduction in the feed gas temperature, the dew point temperature of the output was reduced by 1.6°C. Due to high amount of absorbent and its heat capacity compared to the amount of H2S in the gas phase, a slight temperature increase occurs along the tower so that the difference between inlet and outlet temperatures does not exceed 1˚C. According to the breakthrough curve, it was also determined that after 7920 seconds, the entire bed of the tower is saturated with H2S molecules.