Optimal Flow Rate Research Articles

Solar powered hybrid desalination system using a novel evaporative humidification tower: A numerical investigation

This research describes a hybrid solar desalination system that includes a humidification-dehumidification unit as well as a solar still unit. The current system is being studied numerically. A one-dimensional model of the important heat and mass exchanges, as well as the flow field, was built using the finite difference method. Freshwater productivity is calculated under various operating and weather conditions. The model has been modified to investigate the steady-state behavior of the system components. Four major parameters that have a significant impact on system water production are investigated: the feed flow rate of cooling water through the dehumidifier unit, the airflow rate, and the number and height of packing columns. According to the results, the proposed hybrid desalination system provides appropriate operational compatibility between HDH technology and solar energy. The system can provide a daily production of up to 35 liters per day. Increasing the number of packing columns results in a higher increase in fresh water productivity than increasing the height of the packing columns. The optimal air flow rate at a constant saline-water flow rate is obtained. For high airflow rates, the packing column height doesn't significantly affect the daily water production. System performance is investigated by four main parameters: gained output ratio (GOR), humidifier efficiency, exergy efficiency, and system efficiency. The system efficiency reached about 65% and the GOR reached 3.1. The humidifier’s efficiency varied between 50% and 75%. The maximum exergy efficiency reached about 5.2%.

Parametric optimization for hardness of tig welded duplex stainless steel

Achieving optimal mechanical properties in welding joints hinges on employing precise parametric conditions. This is particularly crucial for Tungsten Inert Gas (TIG) welding of ASTM/UNS 2205 Duplex Stainless Steel (DSS), where attributes like hardness, ultimate tensile strength, and yield strength are paramount. Maintaining high Hardness Value (HV) demands proper welding parameters such as welding current, gas flow rate, and welding speed. To enhance DSS welding quality, especially hardness, this study utilizes the Taguchi method to optimize welding process parameters. The importance of each factor is assessed through Annova statistical analysis. The outcomes highlight the positive impact of parametric optimization on HV, as evidenced by the analysed data. Parametric optimization proves to be a potent approach for refining industrial processes like welding, with particular relevance in TIG welding of duplex stainless steel due to its mechanical robustness and corrosion resistance. Nevertheless, challenges arise due to the material's elevated hardness and low thermal conductivity, resulting in potential defects like cracks and porosity. The identification of optimal welding parameters, encompassing current, voltage, speed, and gas flow rate, helps address these challenges and advances high-quality welds. Through systematic variations and analysis of these parameters, researchers and engineers can pinpoint the optimal combination that mitigates defects while maximizing desired joint attributes. Within the realm of TIG welding of duplex stainless steel, metric optimization holds the potential to elevate welding quality, curtail costs and waste, and heighten productivity and safety. Consequently, organizations can attain enhanced performance, efficiency, and profitability within their welding processes

Techno-economic assessment of retrofitted parabolic trough collector for Kalina power cycle

In this study, the integration of a Kalina cycle with a parabolic trough collector (PTC) was proposed. The PTC underwent retrofitting with a dual-layer coating on the receiver tube, consisting of an inner layer of MXene-doped black paint and an outer layer of silicon oxide anti-reflective coating. This coating configuration aimed to reduce re-radiation losses and enhance the solar absorptivity of the absorber surface. Additionally, MXene (Ti3C2) nanoparticle with weight concentration (0.05–0.3 wt%) is suspended in de-ionized water with varying flow rate (1–5 lpm) is used as heat transfer fluid owing to its superior thermophysical and heat transfer capabilities. Experimental analysis and mathematical modeling are conducted to assess thermal and economic performance. The outcomes reveals optimal weight concentration and flow rate to be 0.15 wt% and 3 lpm, respectively. Comparing conventional and coated PTCs, the maximum thermal efficiency was reported as 48.17% and 58.5%, respectively. The corresponding maximum useful heat generation values were approximately 422.72 kW and 513.312 kW. The thermal efficiency of the Kalina cycle calculated was 11.10%. The conventional PTC-driven Kalina cycle had a Levelized cost of electricity of $0.164/kWh and a payback period of 7 years. Meanwhile, the coated PTC-driven Kalina cycle had a Levelized cost of electricity of $0.15/kWh and a payback period of 6.42 years. The study's findings highlight the superior performance and economic feasibility of the coated PTC-driven Kalina cycle over the conventional PTC setup.

Artificial intelligence based prediction of optimum operating conditions of a plate and fin heat exchanger under uncertainty: A gray-box approach

This study is based on gray-box modeling for the prediction of optimum mass flow rates of inlet streams of a Plate and Fin Heat Exchanger under uncertainty. A first principle model of the Plate and Fin Heat Exchanger was developed in Aspen Exchanger Design and Rating. Genetic algorithm was integrated with the first principle model to achieve the highest possible exit temperature of the cold process stream under uncertainty. A dataset of uncertain process conditions and their corresponding optimum inlet flow rates derived through the first principle-genetic algorithm integration was used to develop an artificial neural networks model. The artificial neural networks model was then integrated with the first principle model by replacing the genetic algorithm to form a novel gray-box framework. The proposed gray box model, i.e., artificial neural networks and first principle integration, achieved a higher effectiveness and higher outlet temperature than those derived through the straight run first principle model. The performance of the gray box framework was also comparable to the first principle integrated genetic algorithm approach and significantly minimized the computation time needed for estimating the optimum process conditions. First principle integrated genetic algorithm approach enhanced the effectiveness of the straight run model by 3.05%. Performance of the proposed gray-box model was comparable to the integrated framework of the genetic algorithm with the first principle model but was significantly faster. The developed artificial neural networks model was employed as a surrogate in Sobol and FAST sensitivity analysis framework to identify the impact of input variables on output variables. The proposed gray box based method enhanced the capability of the plate and fin heat exchanger to recover energy from the process stream and its robustness to cope with uncertainty. The proposed approach is suitable for real-time application and would contribute to laying a foundation for petroleum refinery 4.0.

Design and Analysis of a Novel Air Bubble Curtain for Mixing and Aeration in Process Vessels

This article focuses on designing and analyzing a new method for mixing in process vessels. We propose using an air bubble curtain to accomplish the desired mixing. The air bubble curtain used in this study is made of an empty pipe with several holes through which air is pumped, which in turn produces a swarm of bubbles that causes pseudo-turbulent mixing in the tank filled with a liquid solution. A uniform distribution of bubbles within the tank was assured by maintaining a see-saw movement of the air bubble curtain. Mixing inside the tank was quantified by measuring the salt concentration in a laboratory model tank (30 cm × 30 cm × 30 cm) and a pilot-scale tank (200 cm × 100 cm × 100 cm). The optimal flow rates of air and the mixing time in both tanks that can achieve complete mixing were obtained from the experimental results. The proposed air bubble curtain can be of potential use in wastewater treatment, biotechnology, and aquaculture where turbulent mixing is required with minimum energy dissipation per unit mass.

Steam electrolysis in solid oxide electrolytic cells using a cermet of copper and gadolinia doped ceria cathode

Rising concerns on CO2 emissions and depletion of fossil fuels have led to the quest for developing technologies that aim to produce hydrogen via renewables-powered zero-emission electrolytic pathways. Solid oxide electrolytic cell (SOEC) is such an emerging technology since it is expected to produce higher electric efficiency compared to other state-of-the-art electrolysers like proton exchange membrane (PEM) and alkaline electrolytic cell (AEL). However, SOEC technology is limited by a dearth of high-temperature redox stable electrocatalytically active cathode materials and is currently relying mainly on the materials used as fuel electrodes in solid oxide fuel cells (SOFC). This work investigates the electrochemical performance of three different cathodes comprising cermets of copper and gadolinia doped ceria (Cu-GDC) for steam electrolysis at 800 °C in tubular SOEC under varying steam flow conditions and applied voltages. Remarkably, a polarisation resistance as low as 0.42 Ωcm2 was obtained at 1.60 V with a corresponding Faradaic efficiency more than 95%. A comparison of the trends depicted by current density versus steam flow rate clearly indicated that at any operating temperature, optimum steam flow rate required for maximum current density was governed by the concentration of electrocatalytically active sites. Similarly, a comparison of the voltage-current characteristics of both the cells revealed that Cu content as low as 30 wt% can impart sufficient electronic conductivity as well as catalytic activity to achieve current densities only 15–20% lower than what is obtained with 70 wt% Cu. Finally, 90 min short-term testing of both the cells at 1.60 V under 23% H2/77% steam (v/v) indicated no signs of performance degradation.

Pengaruh Gas Inert Nitrogen Yang Dialirkan Secara Kontinyu ke Dalam Reaktor Pirolisis Limbah Biomassa Serbuk Gergaji Batang Kelapa (Cocos nucifera) Terhadap Nilai Kalor Charcoal yang di Hasilkan

AbstractThe potential amount of coconut sawdust biomass in Indonesia is very abundant, so far it has not been utilized optimally and tends to be wasted as waste. Coconut sawdust with the main composition of carbon contains heat equivalent to light coal, which is around 4400 kcal/kg. Even though its calorific value is still low, it has the potential to be used as a solid fuel source or an alternative energy source. The calorific value of coconut sawdust can be increased through the pyrolysis process. A study has been carried out on the effect of nitrogen inert gas flowing continuously into the pyrolysis reactor of coconut sawdust biomass waste (Cocos nucifera) on the calorific value of the resulting charcoal. The aim of the research is to determine the effect and optimum flow path of nitrogen inert gas which gives the maximum calorific value of charcoal product. From this study it was concluded that the continuous flow of inert nitrogen gas into the pyrolysis reactor had an effect on increasing the calorific value of the charcoal product by up to 4% compared to not using the inert gas. The optimum nitrogen gas flow rate is 2 L/minute giving a maximum effective calorific value of 7200 kcal/kg

Model-based nonlinear dynamic optimisation for the optimal flow rate of vanadium redox flow batteries

The control of the electrolyte flow rate is crucial to ensure the efficient operation of a vanadium redox flow battery (VRFB) system. In this paper, a model-based nonlinear dynamic optimisation (MNDO) method is proposed and implemented in MATLAB/Simulink to study the optimal flow rate under constant current (CC) and constant current–constant voltage (CC–CV) charging methods for a VRFB. A 5 kW/3 kWh VRFB system is considered to investigate the feasibility and accuracy of the established model. System efficiency is the optimisation objective in this study, where all case studies are carried out within 15% to 85% state of charge (SOC). The simulation results show that the proposed method enhanced battery performance by improving the overall VRFB system efficiency under different charging methods. Furthermore, the simulation results show that the CC–CV method is more energy-efficient than the CC method but requires more charging time. An in-depth analysis is carried out to discuss the underlying merits of the proposed method in balancing the losses caused by the concentration overpotential and pump energy consumption in a varying power environment. Moreover, further analyses are carried out to highlight the merits of the CC–CV charging method in saving energy while charging and reducing system imbalance. Finally, a 2D lookup table is designed based on the results from the proposed MNDO method that offers a practical controller of the electrolyte flow rate without requiring excessive computational resources. The performance of the 2D lookup table has been evaluated within 100 charging/discharging cycles. It achieves a system efficiency gain of up to 1.48% under CC–CV charging operation compared with the CC charging method and optimal conventional flow rate control method.

Advanced Flowrate Control of Petroleum Products in Transportation: An Optimized Modified Model Reference PID Approach

Efficient flowrate control is paramount for the seamless operation and reliability of petroleum transportation systems, where precise control of fluid movement ensures not only operational efficiency but also safety and cost-effectiveness. The main aim of this paper is to develop a highly effective modified model reference PID controller, tailored to ensure optimal flowrate control of petroleum products throughout their transportation. Initially, the petrol transportation process is analyzed to establish a suitable mathematical model based on vital factors like pipeline diameter, length, and pump attributes. However, using a basic first-order time delay model for petrol transportation systems is limiting due to inaccuracies, variable delay issues, safety oversights, and real-time control complexities. To improve this, the delay portion is approximated as a third-order transfer function to better reflect complex physical conditions. Subsequently, the PID controller is synthesized by modifying its structure to address flowrate control issues. These modifications primarily focus on the controller’s derivative component, involving the addition of a first-order filter and alterations to its structure. To optimize the proposed controller, the genetic, black hole, and zebra optimization techniques are employed, aiming to minimize an integral time absolute error cost function and ensure that the outlet flow of the controlled system closely follows the response of an appropriate reference model. They are chosen for their proficiency in complex optimization to enhance the controller's effectiveness by optimizing parameters within constraints, adapting to system dynamics, and ensuring optimal conditions. Through simulations, it is demonstrated that the proposed controller significantly enhances the stability and efficiency of the control system, while maintaining practical control signals. Moreover, the proposed modifications and intelligent tuning of the PID controller yield remarkable improvements compared to previous related work, resulting in a 36% reduction in rise time, a 63% reduction in settling time, an 80% reduction in overshoot, and a 98% reduction in cost value.

Optimization of inserted coiled tube three-fluid heat exchanger using genetic algorithms

The three-fluid heat exchanger is a multi-stream heat exchanger that provides three streams at different temperatures for certain usage objectives. Recently, optimizing heat exchangers generally and three-fluid heat exchangers especially have received great attention in the energy field. The current study objective is to get the optimal mass flow rate of the three streams to minimize the entropy generation number and maximize effectiveness. Optimization is performed on the inserted coiled tube type for 24 cases with different usage objectives and different mass flow rate constraints. The optimization is done using an analytical approach for the temperature profiles and a regressed model for the overall heat transfer coefficients. Single-objective and multi-objective genetic algorithms are the optimization algorithms. The result shows that cooling the hot fluid is the most efficient usage objective; however, heating the intermediate-temperature fluid is the less efficient usage objective. Also, the study shows that the entropy generation number is dependent on the mass flow rate constraint. The maximum effectiveness of 0.693 occurs when the usage objective is cooling the hot fluid. In this case, the mass flow rate of the cold and the intermediate-temperature fluids are maxima while the mass flow rate of the hot fluid is minimum. The minimum entropy generation number 0.0486 occurs when the mass flow rate of the cold fluid is maximum while the mass flow rate of the hot fluid and intermediate-temperature fluid are minimal.

New Design Valve in Flow Injection System for the Determination of Pb(II) in Biological and Environmental Samples

A strategy to design an injection valve for a streamlined flow injection technique is described as speed and low-cost materials available in the environment for the determination of Pb(II) ion using the organic reagent 4-((4-methoxyphenyl)diazenyl)benzene-1,3-diol at a wavelength of 498 nm. The scope of the study is to find the optimal conditions, including the flow rate of the carrier, the dispersion coefficient, the length of the reaction coil, and the calibration drawing. The results showed that the optimum length of the reaction coil is 20 cm, and the optimum flow rate is 9.1 mL/min, which is equivalent to the pumping rate of 70 F/min. The range of linearity of the study was revealed by a calibration curve of 0.5–27 mg/L, slope = 1.507, correlation coefficient = 0.9995, the limit of quantitative (LOQ) = 0.088 mg/L, and limit of detection (LOD) = 0.026 mg/L. The system under study has a characteristic efficiency. The dispersion coefficient was calculated for concentrations of 10–15 mg/L Pb(II) ion. Furthermore, the accuracy of the flow injection technique in the estimation process was studied and compared with the Flame Atomic Absorption Spectroscopy (FAAS) technique.

Performance evaluation of a novel humidification-dehumidification desalination system operated by a heat pump

Decentralized and small-scale desalination technologies can effectively address the limitations associated with large-scale desalination systems and contribute to solving the issue of fresh water scarcity. However, low energy efficiency remains a primary obstacle in their widespread application. To tackle this challenge, this paper introduces a novel heat pump humidification-dehumidification desalination system, in which humid air from the dehumidifier enters the heat regenerator and heat pump evaporator in sequence, enabling deep dehumidification. Subsequently, the cold air is reheated by the heat regenerator and subcooler before entering the humidifier. This sequential process can increase not only the energy efficiency of heat pump but also the fresh water productivity. Models are proposed and calculated for the theoretical evaluation of the novel system. Firstly, heat pump design parameters are optimized. Subsequently, performances of the novel system under different operation conditions are compared with those of the conventional system. The results indicate that optimizing heat pump system design parameters can significantly improve system performance. When compared to the conventional system, the novel system exhibits significant improvements. It achieves a maximum fresh water productivity of 39.73kg/h, representing an increase of 12.83%, and a maximum gain output ratio of 6.52, which is 13.39% higher. The lowest fresh water production cost is 9.52 $/m3, also a reduction of 5.15%. Additionally, both the novel and conventional systems possess optimal feed temperature and mass flow rate ratio. At last, the optimal performances of the novel system are compared with the reported results, which further validates the thermodynamic and economic advantages of the novel system.

Perchlorate captured by activated carbon derived from dates seed through adsorption technique

<p>In the present research packed bed column with activated carbon which is derived from the natural available dates seed used for exclusion of perchlorate from aqueous sample. The effect of several variables on adsorption performance has been studied, including inlet ion concentration, flow rate, bed height, and temperature.The adsorbent was prepared in two different temperature 400℃ and 800℃ and the depth of column was 5cm and 8cm. The findings showed that the activated column at 400℃ in the depth of 5cm was saturated at 320 min and for 8cm column it is saturated at 300 min. Likewise for 800℃ columns in the depth of 5cm the treatment efficiency attained at 220 min and for 8cm column it was 180 min. It is showed that the optimal flow rate and bed height increase adsorption effectiveness. Gas chromatography (GC) was used to determine the perchlorate concentration in liquid sample after treatment process. The Thomas and Thomson mathematical models were utilized to determine the column's adsorption efficacy, with the maximum R2value of 0.985 for 800°C in an 8 cm column with a removal efficiency of 98.1%. The surface morphology was examined with SEM, FTIR and XRD which proves that the pore changes in the morphology of the adsorbent created homogeneous to heterogeneous formation structure. This comprehensive study shown that activated carbon generated from dates seed is a successful adsorbent for the removal of perchlorate at optimal temperature and bed depth</p>

Continuous Flow Separation of Live and Dead Cells Using Gravity Sedimentation.

The separation of target cell species is an important step for various biomedical applications ranging from single cell studies to drug testing and cell-based therapies. The purity of cell solutions is critical for therapeutic application. For example, dead cells and debris can negatively affect the efficacy of cell-based therapies. This study presents a cost-effective method for the continuous separation of live and dead cells using a 3D resin-printed microfluidic device. Saccharomyces cerevisiae yeast cells are used for cell separation experiments. Both numerical and experimental studies are presented to show the effectiveness of the presented device for the isolation of dead cells from cell solutions. The experimental results show that the 3D-printed microfluidic device successfully separates live and dead cells based on density differences. Separation efficiencies of over 95% are achieved at optimum flow rates, resulting in purer cell populations in the outlets. This study highlights the simplicity, cost-effectiveness, and potential applications of the 3D-printed microfluidic device for cell separation. The implementation of 3D printing technology in microfluidics holds promise for advancing the field and enabling the production of customized devices for biomedical applications.

Numerical simulation of a multistage magnetic refrigeration system in the temperature range of liquid hydrogen

Magnetic refrigeration is an important new refrigeration technology in the temperature range of liquid hydrogen. A multistage magnetic refrigeration system between 20 K and 80 K has been proposed, which includes three-stage active magnetic regenerators (AMRs). Based on the multistage system, a two-dimensional transient AMR model is established to research the cycle performance mechanism by considering the compressibility of helium, which has not been done before. Firstly, to simplify the simulation difficulty, the AMR model with ideal magnetocaloric materials (the constant isothermal entropy change of 5.4 J/(kg·K) at 1 T) are investigated in the temperature range between 60 K and 80 K. Some parameters including particle diameter, fluid flow fraction, and filling mass of magnetocaloric materials have been compared and analyzed. Based on the above simulation results, the AMR model with real magnetocaloric materials has been done. In the three-layer AMR, the maximum cooling power of 71.04 W at the cooling temperature of 60 K has been obtained, which is 80.17% larger than that of the one-layer AMR. Then, the cooling performance of the multistage magnetic refrigeration system has been studied. In the system, six magnetocaloric materials are filled in three-stage AMRs based on the filling method of adiabatic temperature change. With the optimal mass flow rates of each stage AMR, the maximum cooling power of 40.09 W has been obtained in the multistage system, and the corresponding thermodynamic second efficiency has been 28.14%.

Deep utilization of salinity gradient energy between concentrated seawater and river water by multi-stage reverse electrodialysis

While concentrated seawater discharged by desalination plants requires considerable efforts to alleviate undesired environmental risk, the conversion of salinity gradient energy to electric energy is considered an ideal way. In this work, the experiment and simulation of multi-stage reverse electrodialysis (MS-RED) were carried out, and the influence of flow rate and compartment thickness of high concentration compartment (HCC) and low concentration compartment (LCC) on the MS-RED performance were investigated independently for the huge concentration difference between HCC and LCC. The optimized flow rates of LCC and HCC were 0.96 cm·s−1 and 0.71 cm·s−1, and the compartment thicknesses of LCC and HCC were 1.05 mm and 0.85 mm, respectively. Furthermore, the performance of series multi-stage reverse electrodialysis (SMS-RED) and independent multi-stage reverse electrodialysis (IMS-RED) was compared, and SMS-RED showed better performance than IMS-RED. With the optimized conditions of SMS-RED, the power generation and energy efficiency were reached 684.07 W and 16.22 % after 20 stages, respectively, while the concentration of concentrated seawater was reduce from 66.70 to 37.63 g·L−1. The results can provide a theoretical basis for the industrial development of MS-RED to achieve the deep utilization of concentrated seawater and reduce the environmental risks of its direct discharge.

Experimental investigation on PEM fuel cell flooding mitigation under heavy loading condition

Water flooding is a crucial factor affecting the lifetime of a proton exchange membrane (PEM) fuel cell. In this paper, A laboratory-scale (25 cm2) single PEM fuel cell was tested to investigate the characteristics of fuel cell under a load shedding process with various air flow rates. The performance was assessed using output power and electrochemical impedance spectroscopy, while the cathode flooding was identified using voltage and cathode pressure drop. The results show that reducing the load within a specific range can lower the impedance and lessen floods. The results also demonstrate that there is an optimal inlet flow rate interval considering its effect on system efficiency, durability, and water flooding. In addition, a stepped load shedding pattern was proposed to solve the flooding problem of a fuel cell while taking the power demand into account. The effect of load shedding cycle and air inlet flow rate on flooding was evaluated by comparing the flooding severity coefficient and output power. The results prove that a longer current reduction cycle is more favorable in alleviating flooding problems. The optimal mode for the fuel cell in this paper was determined according to the flooding situation and power variation. Finally, the approach to obtaining the optimal load shedding pattern for other PEM fuel cells system was summarized. The flooding mitigation approach proposed in this paper can be utilized as a guide for developing strategies to extend the life of PEM fuel cells.

Experimental investigation of acrylonitrile butadiene styrene plastics plasma gasification

E-waste comprising plastics causes serious ecological problems due to low degradability, but it is capable of producing a high amount of energy by thermochemical conversion. Therefore, the current study focuses on generating clean syngas through plasma gasification of acrylonitrile butadiene styrene (ABS) based computer keyboard plastic waste (CKPW) using CO2 as a gasifying agent. The effect of feed rate, gas flow rate and plasma power on the syngas composition was studied. In addition, a comprehensive investigation of energy, exergy, economic and environmental analyses along with characterization of the obtained products was conducted to evaluate the performance of the system. Based on the experimental results, the optimum process parameters for producing syngas possessing a higher calorific value (15.80 MJ/m3) with a higher percentage of H2 (30.16 vol%) and CO (46.09 vol%) were estimated. The optimum feed flow rates of solid fuel and CO2 gas and torch power were estimated as 40 g/10 min, 0.5 lpm and 1.12 kW, respectively. At these conditions, the system could achieve a maximum energy and exergy efficiency of 46.06% and 44.34%, respectively, while the levelized cost of syngas (LCOSover) was estimated as 25.45 INR/kWh, including the social cost. Likewise, the lower values of the estimated global warming potential (370.19 gCO2eq/h) illustrate the better sustainability of the process. The obtained oil with the estimated LHV of 39.13 MJ/kg could be an alternative fuel for diesel and the residue containing a higher proportion of TiO2 has medical applications upon further enrichment. The reaction mechanism of ABS conversion to syngas under plasma gasification conditions is proposed.

Development of a calculation scheme for selecting the optimal mode of operation of a gas condensate well taking into account the deformation conditions of the formation

To establish premature optimal well operation modes, it is necessary to consider the process of well operation within the framework of ongoing processes in the common reservoir-well hydrodynamic system and take into account the peculiarities of changes in the properties of the gas condensate mixture and the thermobaric conditions of the reservoir in it. Therefore, the object of the study is the operation of a gas condensate well in the event of technological complications in it, which requires the selection of the necessary optimal operating mode to prevent these complications by comprehensively taking into account the factors influencing this process in the “reservoir-well” system.
 The article proposes a calculation scheme for establishing the optimal operating mode of a gas condensate well without the formation of a liquid plug at the bottomhole, taking into account the formation deformation during field development in the depletion mode. The problem is solved by determining the required current working volume of produced gas (as well as condensate), bottomhole and contour values of reservoir pressure, condensate saturation and reservoir porosity. As a result of the study, it was revealed that the determined characteristics of the selected optimal mode of a gas condensate well are significantly affected by a change in the reservoir properties of the reservoir (for example, the permeability of the reservoir), which in turn leads to a change in the optimal working gas flow rate of the well.
 The considered problem has not been previously studied in its full formulation, which is presented in this article, where the solution of the problem under study is achieved taking into account the change in the physical properties of the reservoir fluid and gas, as well as the reservoir properties of the reservoir under conditions of a change in the state of the reservoir system due to emerging deformation processes in the reservoir

Investigation of the flow rate optimization of the Zn/LiFePO4 aqueous flow battery

Zn/LiFePO4 aqueous flow batteries are regarded as promising energy storage technologies due to their low cost, high safety, and high energy density, but the short cycle life hinders the further applications. In this work, the cycle life is improved by optimizing the electrolyte flow rate. The results show that as the flow rate increases, the capacity retention rate of the battery shows an initial increase but followed by a decrease. Compared with the capacity retention rate of 86.05% after 100 cycles with no flow, the capacity retention rate at the optimal flow rate of 0.25 mL min−1 can reach 106.35 %. Simulation results show that flow improves the uniformity of the electrolyte to some extent and reduces concentration polarization. For the decay of the capacity retention rate at high flow rates, two hypotheses are proposed, including the conjecture of “dead zone” and concerns about the effects of high flow rates on desolvation and adsorption processes based on the test results. In the future, more means are expected to be used to explore its mechanism more accurately. This work provides insights into the mechanisms of flow effects on cycle life and provides ideas for flow rate optimization for other types of flow batteries.