Multistage System Research Articles

Modeling of reconfigurable manufacturing system architecture with geometric machines and in-stage gantries

Reconfigurable Manufacturing Systems (RMSs) are well recognized by their capability to achieve high responsiveness and flexibility and are receiving increasing interest in today’s versatile manufacturing environment. This paper aims to develop methods to study the performance of RMS architecture consisting of machines and in-stage gantries whose time to failure and time to repair follow geometric distributions. A discrete-time Markov chain model is built to perform an exact analysis for two-stage-one-buffer systems. A decomposition method is developed to analyze multi-stage systems. Moreover, both time-dependent failure and operation-dependent failure modes are considered. Numerical studies that compare the calculated production rate and work-in-process to the simulation results demonstrate that the proposed methods can provide accurate results, especially for balanced systems and for systems with a small number of stages. The impact of different parameters (e.g., buffer capacity, machine/gantry reliability) on the production rate of the two models is also studied. Finally, examples on the applications of the models in the manufacturing systems design and operations are presented.

Humidity Considerations in Filter Testing Based on Analysis of Filters from Gas Turbine Applications

AbstractDepth filters used in multistage filter systems adeptly clean the intake air of gas turbines, preventing damage and increasing performance. However, estimation of their service life is based on empirical data and/or standardized testing procedures, e.g., ISO 16890. By applying standardized synthetic test dusts at constant reference humidity, these testing procedures do not reflect application‐typical loading conditions. Based on a direct comparison with field data, the influence of temporary exposure to high relative humidity on differential pressure and particle deposit structure is investigated. The results indicate that simulating humidity variations of the ambient atmosphere during filter tests leads to particle deposits, which more accurately reflect the actual behavior during operation.

Performance analysis and optimization of a novel high-efficiency flower-inspired solar still

Solar still provides a potential solution to water shortage in rural areas. However, due to large optical and thermal losses, solar still system suffers from low energy efficiency (30%∼45%). This work aims to present a novel high-efficiency multi-stage floating flower-inspired solar still. To improve the optical performance of the new system, a corolla-shaped concentrator matching the system is designed and optimized through optical simulation. The heat and mass transfer models of the single-stage and multi-stage system were established and validated to study and optimize the performance. The optical simulation result of the corolla-shaped concentrator shows that its light receiving rate is higher than 0.75 with incident angle of 20°. The performance simulation results demonstrate that the water yield rate and the total energy efficiency of the single-stage flower-inspired solar still are 0.85 kg/(m2·h) and 65%, respectively. While the water yield rate and the total energy efficiency of the seven-stage system can reach about 6.5 kg/(m2·h) and 480%, which is 10.66 times higher than the energy efficiency of the conventional solar still system (45%). Furthermore, the economic analysis shows that the cost and the payback period of the seven-stage system are 0.001$/L and 0.25 years, respectively. Therefore, the proposed novel solar desalination system with high efficiency and low cost greatly improves application of solar still in rural areas.

Performance and microbial response in a multi-stage constructed wetland microcosm co-treating acid mine drainage and domestic wastewater

Multi-stage constructed wetland microcosms (mixing and sedimentation pond (MS), vertical-flow constructed wetland (VFCW) and surface-flow constructed wetland (SFCW)) were designed to co-treat high-strength acid mine drainage (AMD) and domestic wastewater, with agricultural waste (straw and cow manure) fermentation liquor as stimulation substrate. The 270-day lab-scale study showed that this system was highly effective in enhancing effluent pH (from 2.5 to 8.1) and removing dissolved metals (89.4% of Mn, and 99% of Fe, Zn, Cd and Cu), sulfate (51.9%) and organic/nutrient pollutants (COD, NH4+-N, NO3--N, and TP). The mixing and sedimentation pretreatment could alleviate the burden (strong acidity and high-strength metals) and clogging of wetlands, and the formed metal-rich sludge offered the possibility of metals reclaiming. Quantitative supplementary of fermentation liquor promoted sulfidogenic activity in VFCW, also avoiding excessive release of organic/nutrient pollutants. SFCW was effective in treating residual metals (especially Mn) and organic/nutrients. High-throughput sequencing test showed that the diverse microbe (such as sulfate reducing bacteria, nitrifying bacteria, and denitrifying bacteria) co-existing in this multi-stage system predominantly contributed to the effective remediation. Metal amounts assimilated by wetland plants were very limited (e.g. 1% for Mn) for metals remediation. The multi-stage constructed wetlands co-treatment system quantitatively supplied with liquid waste as carbon source may offer a promising eco-technology for the remediation of AMD.

Optimal Reactive Power Dispatch Using Multistage Artificial Immune System

Most countries over the past few decades have modernized their economies and become more reliant on electricity to run, so the electrical power system has also expanded greatly. Optimal Reactive Power Dispatch (ORPD) has a big influence on the reliability, security, and economic operation of the power system. Another thing to note is that ORPD has a few major targets and objectives which are to reduce the active or real power losses, to improve the voltage profile, to reduce transmission costs, and to increase system stability. Non-convex, non-linear, and multimodal problems make the development of intelligent algorithms to solve the reactive power dispatch problem highly relevant. Some researchers chose to compare and contrast optimization techniques from the past with each other in order to answer some remaining uncertainties such as the effectiveness and complexity of the technique toward the chosen objective function(s). Thus, this paper proposed applying the Multistage Artificial Immune System (MAIS) optimization method for solving the ORPD problem with the objective of reducing the power system losses. This algorithm was made by modifying and upgrading the classical AIS optimization method. Instead of only going through the process one time in the classical AIS algorithm, this MAIS method going through the processes more than one time in multiple stages of the same processes. This process includes cloning and mutation as well as selection. These modifications also aid in the development of new and unique solutions, as opposed to the classical AIS optimization process. Therefore, these enhancements could lead to a rise in the accuracy of the results' because there have been increased comparisons. This study confirms that MAIS optimization can deliver superior results in less time than AIS. Keywords—Optimal reactive power dispatch, computational intelligence, multistage artificial immune system, loss minimization.

An Evaluation of the Equilibrium Properties in Hexane and Ethanol Extractive Systems for Moringa oleifera Seeds and Fatty Acid Profiles of the Extracts

Until the present, oilseed extractions have been mainly performed using hexane: a toxic, non-sustainable solvent. Extraction methods using ethanol have recently been proposed and, to evaluate the suitability of ethanol as an alternative solvent, Moringa seeds with an oil content as high as 40% have been chosen to determine the equilibrium properties in solid–liquid ethanol extractions. The equilibrium constant (Keq) and the specific retained solution (M) of the extractive systems seeds–oil–hexane and seeds–oil–ethanol were determined and validated, following a counter-current multi-stage extraction model. The extractions were carried out at 40 and 50 °C, the mass to solvent ratios used were 1:5, 1:10 and 1:20, and shelled and unshelled seeds (kernels) were tested. The Keq and M of the different kinetics revealed that Keq was not infinite in the hexane systems, whereas the ethanol systems registered slightly lower values. Regarding M, although the seed powder allowed more rapid extractions, particle size was increased to reduce M for an easier phase preparation. Finally, a counter-current multi-stage extraction system was simulated and applied under suitable conditions. The fatty acid profiles for both types of extract were similar regarding their main components. definition:

Optimal Pricing, Advertising, Production, Inventory and Investing Policies in a Multi-Stage Sustainable Supply Chain

In this paper, the study of a sustainable production–inventory model with price and advertisement dependent on demand considering carbon emission reduction technology is investigated. The aim of this paper is to determine the optimal appropriate pricing, advertising, production, inventory, and capital investment decisions under various carbon emission policies to maximize the joint total profit of a multi-stage supply chain system. Various theoretical results and an algorithm are provided to verify and obtain the optimal solution of the problem. Further, the model is verified by numerical examples, and the robustness check of parameter variation is also analyzed. Finally, some management implications for decision makers are drawn from numerical examples. In summary, this study puts forward more realistic modeling hypothesis, which is beneficial to the academic research, and the research results can provide relevant decision makers with a model for managing a sustainable supply chain.

Tunable Graphene Oxide Nanofiltration Membrane for Effective Dye/Salt Separation and Desalination.

Effective dye separation and desalination are critical for the treatment of highly saline textile wastewater with dye mixtures. In this study, a graphene oxide (GO) membrane with a tunable interlayer distance (d) was fabricated to generate clean water via two-stage filtration, namely, the dye/salt separation and desalination stages. In the first stage, under low pressure (e.g., 0.3 MPa), the membrane with a d value of ca. 7.60 Å was suitable for removing the dye from the saline wastewater. The dye and salt (i.e., Na2SO4) rejection rates of >99% and <6.5% were achieved, respectively, indicating the significant potential to recycle the dyes from the highly saline dye wastewater. In the second stage, under a higher pressure (e.g., 0.8 MPa), the d value was reduced to ca. 7.15 Å, bestowing the membrane with a desalination function. The desalination rate of a single filtration process could reach up to 51.8% from 1.0 g/L saline (i.e., Na2SO4) water. The as-prepared membrane also exhibited excellent practical advantages, including ultrahigh permeability, significant antifouling (against dye) performance, and excellent stability. Furthermore, with the stacking of multistage filtration systems, the proposed membrane technology will be capable of regenerating dye and producing clean water.

A serial system of multi-stage reverse electrodialysis stacks for hydrogen production

Salinity gradient energy is converted to hydrogen energy by integrating reverse electrodialysis (RED) and electrolysis of water to produce hydrogen. In this work, a serial system of multi-stage RED sacks is proposed to improve the energy efficiency and working performance of direct hydrogen production. The experimental results show that, compared with a single-stage system, the multi-stage RED stack system showed significant improvements in both hydrogen production and power output. Appropriately reducing the working current while increasing the number of RED stacks was beneficial to net power output and energy conversion. Total hydrogen production was almost unaffected when the number of RED stacks was large. Maximum energy conversion efficiency occurred at an optimal feed solution velocity. Under these conditions, the maximum net output power, total hydrogen production, and total energy-conversion efficiency were 2.06 W, 881.88 mL h−1, and 7.74%, respectively. The results are of relevance to investigation of the thermal-energy-driven reverse-electrodialysis heat engine for hydrogen production.

Matrix Method for Modelling of Multicomponent and Multistream Energy Systems and Installations of Thermal Power Plants

The aim of this work is to increase the operational efficiency of the multicomponent multithreaded power units and systems of the TPP using modeling, calculation and optimization. The goal is achieved by solving the following tasks: development of the tasks’ classification system and a unified methodology for the mathematical description of energy formation and mass flows’ processes in multicomponent and multithreaded power units of the TPP; development of a model of a steam turbine power unit; development of a model of heat and mass transfer processes in multi-stage multistream multiphase systems. The most significant results obtained were: the developed unified methodology for the matrix description of the processes of energy and mass flows’ formation in multicomponent multistream energy systems of the TPP. Within the framework of the proposed methodology, a model of a steam turbine power was developed; model solutions were obtained and analyzed in order to calculate the energy characteristics of a heating turbine unit, the reliability and validity of the proposed approach was shown, a mathematical model of multistream multi-stage heat exchange systems were developed. The significance of the results obtained consisted in the development of a simple but informative mathematical model of a thermal power plant turbine generator and a model of multistream multi-stage heat exchange systems, each stage of which can have an arbitrary number of input and output flows with a possible phase transition in heat carriers.ave an arbitrary number of input and output flows with a possible phase transition in heat carriers.

Application of dehumidification as anti-corrosion technology on suspension bridges: A review

• Dehumidification is a proactive corrosion protection for suspension bridges’ main cable. • A review on different dehumidification systems on suspension bridges. • Discussion on limitations and adaptations for main cable anti-corrosion application. • Identifying future scenarios and challenges of dehumidification on suspension bridges. The moisture from residual droplets during construction and infiltration of wet air during operation can cause metal corrosion of main cables on suspension bridges. Main cable dehumidification, emerged as a prospective corrosion protection approach, which provides an internal environment of relative humidity below 60%, would significantly mitigate the corrosion. This paper presents a state-of-the-art listicle review of existing dehumidification systems implemented on 47 suspension bridges (e.g., the Akashi Kaikyo Bridge, the Runyang Yangtze River Bridge). Dehumidification methods adopted in suspension bridges, including solid desiccant dehumidification, condensing dehumidification and integrated dehumidification, are elaborated. Based on that, crucial limitations and adaptations of various systems for main cable applications are discussed. Then, technical suggestions concerning the moisture load matching, sensor configurations, full-bridge sealings, dehumidification equipment placement and system division, are given to realize system sustainability and energy efficiency. Finally, this paper examined one potential development of a multi-stage dehumidification system that uses condensing dehumidification and solid desiccant dehumidification, which facilitates cascade utilization of the waste energy and enhances the system efficiency.

Analysis, Modeling, and Simulation of Thin-Film Cells-Based Photovoltaic Generator Combined with Multilayer Thermoelectric Generator.

A new model for a multi-stage thermoelectric generator (TEG) is developed. An electrical and thermal model is built and simulated for different configurations of photovoltaic (PV) stand-alone hybrid systems, combining different stages of a TEG. The approach is evaluated with and without cooling by coupling a cold plate to a multi-stage hybrid PVTEG system. The model can be adjusted by sizing and specifying the influence of stage number on the overall produced power. Amorphous silicon thin-film (a-Si) is less affected by rising temperature compared to other technology. Hence, it was chosen for evaluating the lower limit gain in a hybrid system under various ambient temperatures and irradiances. The dynamics of the PVTEG system are presented under different coolant water flow rates. Finally, comparative electrical efficiency in reference to PV stand-alone was found to be for PVTEG without cooling, for PVTEG, and for multi-stage PVTEG, accordingly installing multi-stage PVTEG at Israel in a typical year with an average PV yield of generates an extra per module hence avoiding fossil energy and equivalent emissions.

Environmental performance evaluation of European farms by assessing polluting factors in joint production

Measuring the environmental efficiency of firms using data envelopment analysis (DEA) has recently gained momentum due to the urgency of climate change. The existing literature on environmental efficiency ignores the internal structures of the production system and treats the production unit as a ‘black box’. Thus, it fails to identify the exact source of inefficiencies, which complicates course correction in a multi-stage production system. In response to these inadequacies, this study takes into account the amount of pollutants emitted, in addition to the classic input and output parameters in DEA, in each of the stages to measure the environmental efficiency of the overall system and decompose it into stage-level environmental efficiencies. Two separate models assign each country two separate efficiency scores for its environmental and technical performance. To demonstrate the applicability of the proposed framework, the environmental performance of farms in the European Union is measured. The numbers of efficient farms in technical and environmental approaches are 21% and 8% of the total 130 farms, respectively. The average environmental efficiency scores of the two stages (crop production and animal husbandry) across the farms are found to sharply increase and decrease, respectively in comparison to their corresponding technical efficiency. The study also reveals some interesting conclusions. For example, the environmental performance improves for inefficient farms when they try to achieve technical competence. To achieve overall environmental efficiency, all the stages need to be fully efficient. Based on the shadow prices of the polluting inputs and outputs obtained from the two models, we calculate the marginal rate of substitution for the inputs and marginal rate of transformation for the outputs which help one in carrying out comparative analysis. For instance, the results indicate that fertilizer and forage land are responsible for the majority of the environmental inefficiency. Production of cereal and meat is economically efficient; whereas dairy farming is both resource-intensive and environmentally harmful. Based on this analysis, we suggest important policy measures at both the farm and the country levels.

Multiobjective Optimization Based on “Distance-to-Target” Approach of Membrane Units for Separation of CO2/CH4

The effective separation of CO2 and CH4 mixtures is essential for many applications, such as biogas upgrading, natural gas sweetening or enhanced oil recovery. Membrane separations can contribute greatly in these tasks, and innovative membrane materials are being developed for this gas separation. The aim of this work is the evaluation of the potential of two types of highly CO2-permeable membranes (modified commercial polydimethylsiloxane and non-commercial ionic liquid–chitosan composite membranes) whose selective layers possess different hydrophobic and hydrophilic characteristics for the separation of CO2/CH4 mixtures. The study of the technical performance of the selected membranes can provide a better understanding of their potentiality. The optimization of the performance of hollow fiber modules for both types of membranes was carried out by a “distance-to-target” approach that considered multiple objectives related to the purities and recovery of both gases. The results demonstrated that the ionic liquid–chitosan composite membranes improved the performance of other innovative membranes, with purity and recovery percentage values of 86 and 95%, respectively, for CO2 in the permeate stream, and 97 and 92% for CH4 in the retentate stream. The developed multiobjective optimization allowed for the determination of the optimal process design and performance parameters, such as the membrane area, pressure ratio and stage cut required to achieve maximum values for component separation in terms of purity and recovery. Since the purities and recoveries obtained were not enough to fulfill the requirements imposed on CO2 and CH4 streams to be directly valorized, the design of more complex multi-stage separation systems was also proposed by the application of this optimization methodology, which is considered as a useful tool to advance the implementation of the membrane separation processes.

Is that your final decision? Multi-stage profiling, selective effects, and Article 22 of the GDPR

Provisions in many data protection laws require a legal basis, or at the very least safeguards, for significant, solely automated decisions; Article 22 of the GDPR is the most notable. - Little attention has been paid to Article 22 in light of decision-making processes with multiple stages, potentially both manual and automated, and which together might impact upon decision subjects in different ways. - Using stylised examples grounded in real-world systems, we raise five distinct complications relating to interpreting Article 22 in the context of such multi-stage profiling systems. - These are: the potential for selective automation on subsets of data subjects despite generally adequate human input; the ambiguity around where to locate the decision itself; whether 'significance' should be interpreted in terms of any potential effects or only selectively in terms of realised effects; the potential for upstream automation processes to foreclose downstream outcomes despite human input; and that a focus on the final step may distract from the status and importance of upstream processes. - We argue that the nature of these challenges will make it difficult for courts or regulators to distil a set of clear, fair and consistent interpretations for many realistic contexts.

Dynamic Modeling of Hydrogen Systems for Grid Operations: Compression and Storage

With the increasing penetration of intermittent renewable resources (e.g., solar and wind) into the power grid, hydrogen production from renewable electrolysis has gained more attention as a large-scale energy storage technology to meet the fluctuating grid demand and improve the resilience of the energy system. Accordingly, the development of economic, efficient and safe hydrogen storage technology is required. High-pressure gaseous hydrogen storage is currently the most suitable solution for long-duration storage due to its technical simplicity, reliability, energy efficiency as well as affordability [1]. Even though compressed hydrogen storage has a fast filling-releasing rate, the increase in the pressure and temperature of hydrogen in the storage tank leads to thermal stress and related safety concerns [2]. With this motivation, a complete system of hydrogen production via electrolysis and high-pressure hydrogen storage was developed. Different filling and releasing cycles and transient responses of the storage tank will be presented.A high-fidelity dynamic model of a Proton Exchange Membrane (PEM) electrolyzer was developed for hydrogen production from an intermittent renewable resource. A parallel multi-stage hydrogen compression system with cascaded filling configuration was modeled and designed. A non-adiabatic lumped dynamic model was developed for the storage tank and the heat conductivity within the tank wall was included. In addition, the thermal stress model was developed to estimate the storage tank stress transient. Different equations of state (e.g., Peng-Robinson or Modified Benedict-Webb-Rubin) were adopted to account for the non-ideal gas response of high-pressure gaseous hydrogen [3]. Under the steady-state condition of 510 kW power, 90 Nm3/hr (i.e., 7.92 kg/hr) of hydrogen can be produced and compressed up to the maximum pressure of 44 MPa. The full capacity of the storage tank would be reached after 72 hr.Different filling and releasing scenarios were implemented depending on the seasons and hydrogen fuel applications. The compressor duty as well as the storage tank pressure and temperature was monitored and controlled. The most effective and economical filling and releasing operation will be presented based on technical and economic analysis.[1] Li, Mengxiao, Yunfeng Bai, Caizhi Zhang, Yuxi Song, Shangfeng Jiang, Didier Grouset, and Mingjun Zhang. "Review on the research of hydrogen storage system fast refueling in fuel cell vehicle." International Journal of Hydrogen Energy 44, no. 21 (2019): 10677-10693.[2] Li, Ji-Qiang, No-Seuk Myoung, Jeong-Tae Kwon, Seon-Jun Jang, and Taeckhong Lee. "A Study on the Prediction of the Temperature and Mass of Hydrogen Gas inside a Tank during Fast Filling Process." Energies 13, no. 23 (2020): 6428.[3] Lemmon, Eric W., Marcia L. Huber, Daniel G. Friend, and Carl Paulina. Standardized Equation for Hydrogen Gas Densities for Fuel Consumption Applications1. No. 2006-01-0434. SAE Technical Paper, 2006.

A highly efficient multi-stage dielectric barrier discharge (DBD)-catalytic system for simultaneous toluene degradation and O3 elimination

DBD-catalytic system has been widely studied for volatile organic compounds abatement, whereas how to obtain high mineralization rate and low zone emission synchronously remains a challenge. In view of this, a new type of multi-stage DBD-catalytic system (MS1) was established to abatement toluene in this study. The mineralization rates of reactors IPC (63.81%) and MS1 (61.14%) were much higher than MS2, PPC1 and PPC2 reactors, which were 48.36%, 46.84%, and 5.8% at 33.8 (Vp-p) kV, respectively. For export ozone concentration, IPC reactor had the highest concentration of 160 ppm, and the values of reactors MS1, MS2, PPC1, and PPC2 were 79, 34.2, 34.25 and 29 ppm, respectively. The catalyst filled in zone II can be utilized to further decompose the residual toluene and intermediates and also promote the decomposition of ozone, which lead to the superior performance of the MS1 reactor. The influence of applied voltage, adsorbed amount, and discharge time on the toluene removal performance was investigated to optimize the operation parameters of MS1 reactor, their appropriate values were 28.3–31.1 (Vp-p) kV, 0.179–0.223 mmol, ∼1 h, respectively. Lastly, the contribution of disparate zones in multi-stage DBD-catalytic system to the toluene degradation were elucidated on the basis of the GC–MS results.

Control strategies comparison for a multi-stage assembly system using simulation

The goal of Zero Defect Manufacturing (ZDM) is to reduce part scrap by compensating manufacturing deviations and avoiding their propagation on multi-stage production systems. In particular, the joint use of in-process measuring and flexible locating systems enables the application of different control strategies to proactively improve the geometrical quality of the product and to achieve the productivity targets. In this work, focused on the production quality paradigm, two compensation strategies based on the adjustment of part locators are simulated to compare how different control loops can reduce the out-of-control parts in multi-stage assembly systems. For this purpose, a simulation tool developed on OpenModelica is used taking into account the logistic flow and the quality characteristics flow based on the Stream of Variation model.

Microplastic abundance, characteristics and removal in large-scale multi-stage constructed wetlands for effluent polishing in northern China

Wastewater treatment plants (WWTPs) are considered to be an important source of microplastics (MPs) to the aquatic environment. Multi-stage constructed wetlands (CWs) are widely used for the advanced treatment of effluent from the WWTPs. Research on the abundance, characteristics, and removal of MPs in multi-stage CWs is limited. Therefore, we studied two large-scale multi-stage CW systems (Lingang Ecological Wetland Park and Konggang CW system) in Tianjin, China. The removal efficiency of MPs in two CW systems was greater than 89.0% (from 8.4 to 28.9 particles L−1 in the influent to 0.2–0.9 particles L−1 in the effluent). During the treatment, the horizontal subsurface flow CWs (HSSFCWs) in Lingang Ecological Wetland Park and the integrated vertical flow CWs (VFCWs) in Konggang CW system removed 82.8%-88.9% of MPs. 27.3%-60.0% of MPs were removed by surface flow constructed wetland (SFCW) in two CW systems. Among detected MPs, five types of polymers were identified by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), including polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE). The characteristics of MPs, such as sizes, shapes, and types influenced the removal of MPs in various treatment processes in two CW systems. Specifically, microfibers could be intertwined to form coils by hydraulic action, and effectively removed by HSSFCWs. Results of the present study indicated that large-scale multi-stage CW systems could substantially reduce the MP pollution discharged from WWTPs into the aquatic environments, and provided a theoretical basis for understanding the migration and distribution of MPs in the aquatic environment.

Reactor Design for Biogas Production-A Short Review

Biogas is an alternative to gaseous biofuels and is produced by the decomposition of biomass from substances such as animal waste, sewage sludge, and industrial effluents. Biogas is composed of methane, carbon dioxide, nitrogen, hydrogen, hydrogen sulfide, and oxygen. The anaerobic production of biogas can be made cheaper by designing a high throughput reactor and operating procedures. The parameters such as substrate type, particle size, temperature, pH, carbon/nitrogen (C/N) ratio, and inoculum concentration play a major role in the design of reactors to produce biogas. Multistage systems, batch, continuous one-stage systems, and continuous two-stage systems are the types of digesters used in the industry for biogas production. A comprehensive review of reactor design for biogas production is presented in the manuscript.