Processes

15 pages, 2259 KiB

Open AccessFeature PaperArticle

Biogas Purification: A Comparison of Adsorption Performance in D4 Siloxane Removal Between Commercial Activated Carbons and Waste Wood-Derived Char Using Isotherm Equations

by Davide Papurello, Marta Gandiglio, Jalal Kafashan and Andrea Lanzini

Processes 2019, 7(10), 774; https://doi.org/10.3390/pr7100774 - 22 Oct 2019

Cited by 38 | Viewed by 5731

Abstract

Biogas production from organic waste could be an option to reduce landfill and pollutant emissions into air, water, and soil. These fuels contain several trace compounds that are crucial for highly efficient energy generators or gas injection into the grid. The ability of [...] Read more.

Biogas production from organic waste could be an option to reduce landfill and pollutant emissions into air, water, and soil. These fuels contain several trace compounds that are crucial for highly efficient energy generators or gas injection into the grid. The ability of adsorbents to physically remove such adsorbates was investigated using adsorption isotherms at a constant temperature. We experimentally modelled isotherms for siloxane removal. Siloxanes were considered due to their high impact on energy generators performance even at low concentrations. Octamethylcyclotetrasiloxane was selected as a model compound and was tested using commercially available carbon and char derived from waste materials. The results show that recyclable material can be used in an energy production site and that char must be activated to improve its removal performance. The adsorption capacity is a function of specific surface area and porous volume rather than the elemental composition. The most common adsorption isotherms were employed to find the most appropriate isotherm to estimate the adsorption capacity and to compare the sorbents. The Dubinin-Radushkevich isotherm coupled with the Langmuir isotherm was found to be the best for estimating the adsorption capacity. Full article

(This article belongs to the Section Environmental and Green Processes)

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19 pages, 7044 KiB

Open AccessFeature PaperArticle

Comparison of Temperature Control and Temperature Difference Control for a Kaibel Dividing Wall Column

by Xing Qian, Rui Liu, Kejin Huang, Haisheng Chen, Yang Yuan, Liang Zhang and Shaofeng Wang

Processes 2019, 7(10), 773; https://doi.org/10.3390/pr7100773 - 21 Oct 2019

Cited by 10 | Viewed by 3435

Abstract

A dividing wall column (DWC) effectively intensifies the distillation process with a reduced energy consumption, capital investment, and space. The three-product DWC has been investigated intensively and extensively; however, the four-product Kaibel DWC has received scarce attention. This study aimed to propose feasible [...] Read more.

A dividing wall column (DWC) effectively intensifies the distillation process with a reduced energy consumption, capital investment, and space. The three-product DWC has been investigated intensively and extensively; however, the four-product Kaibel DWC has received scarce attention. This study aimed to propose feasible control structures for the Kaibel DWC using only temperature sensors in order to promote its industrialization. Two temperature control structures, two temperature difference control structures, and two double temperature difference control structures were studied. The feasibility of the six proposed control structures was verified with a wide variety of feed disturbances. In most cases, temperature difference control was better than temperature control to maintain product purities. The dynamic performances proved that the inserted feed disturbances were handled well. These results help to promote the industrialization of the Kaibel DWC. Full article

(This article belongs to the Special Issue Process Optimization and Control)

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18 pages, 5532 KiB

Open AccessArticle

Experimental Study on Forced Convection Heat Transfer from Plate-Fin Heat Sinks with Partial Heating

by Jae Jun Lee, Hyun Jung Kim and Dong-Kwon Kim

Processes 2019, 7(10), 772; https://doi.org/10.3390/pr7100772 - 21 Oct 2019

Cited by 12 | Viewed by 7303

Abstract

In this study, plate-fin heat sinks with partial heating under forced convection were experimentally investigated. The base temperature profiles of the plate-fin heat sinks were measured for various heating lengths, heating positions, flow rates, and channel widths. From the experimental data, the effects [...] Read more.

In this study, plate-fin heat sinks with partial heating under forced convection were experimentally investigated. The base temperature profiles of the plate-fin heat sinks were measured for various heating lengths, heating positions, flow rates, and channel widths. From the experimental data, the effects of heating length, heating position, and flow rate on the base temperature profile and the thermal performance were investigated. Finally, the characteristics of the optimal heating position were investigated. As a result, it was shown that the optimal heating position was on the upstream side in the case of the heat sinks under laminar developing flow, as opposed to the heat sinks under turbulent flow. It was also shown that the optimal heating position could change significantly due to heat losses through the front and back of the heat sink, while the effects of the heat loss through the sides of the heat sink on the optimal heating position were negligible. In addition, it was shown that the one-dimensional numerical model with empirical coefficients could predict the important trends in the measured temperature profiles, thermal resistances, and optimal heating lengths. Full article

(This article belongs to the Special Issue Optimization of Heat and Mass Exchange)

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18 pages, 1193 KiB

Open AccessArticle

A Time-Sequence Simulation Method for Power Unit’s Monthly Energy-Trade Scheduling with Multiple Energy Sources

by Liang Sun, Qi Zhang, Na Zhang, Zhuoran Song, Xinglong Liu and Weidong Li

Processes 2019, 7(10), 771; https://doi.org/10.3390/pr7100771 - 21 Oct 2019

Cited by 5 | Viewed by 2924

Abstract

The uncertainty of new energy output from wind power is rarely considered in the monthly energy-trade scheduling. This causes many problems since the new energy penetration level increases. The fairness of the scheduled energy for the power suppliers is difficult to guarantee. Because [...] Read more.

The uncertainty of new energy output from wind power is rarely considered in the monthly energy-trade scheduling. This causes many problems since the new energy penetration level increases. The fairness of the scheduled energy for the power suppliers is difficult to guarantee. Because the actual power system operation is far away from scheduling when the monthly energy-trade schedule is carried out, unnecessary wind curtailment might occur, and even the feasibility of monthly energy-trade schedule might not be guaranteed. This affects the security and reliability of the power system operation. In this paper, a new time-sequence simulation method for the monthly energy-trade scheduling is proposed, which considers the new energy power forecasting characteristic and the computational load problem of hourly energy-trade simulation in the remaining months. The proposed method is based on a segment modelling strategy. The power generation in the scheduling month is optimized hourly, and the energy generation is optimized in the subsequent months on a monthly basis. For the scheduling month, accurate cost function is applied in the objective function, and detailed short-term operation constraints and the new energy forecasting results are considered, which can guarantee the feasibility of the new monthly energy-trade scheduling and lay a solid foundation for daily dispatching. For the subsequent months, since the load forecast accuracy is lower and no wind power forecasting results could be used, the rough cost function is applied, and only monthly constraints are considered. To ensure a balance in the execution progress of each power generating entity, the simulation time-scale is set as the remainder of the months in the study year. The new approach ensures the fairness of power execution progress and improves the new energy consumption level. A case study was used to verify the feasibility and effectiveness of the proposed method, which provides a theoretical reference for the monthly electrical energy-trade scheduling. Full article

(This article belongs to the Special Issue Advances in Theoretical and Computational Energy Optimization Processes)

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12 pages, 2500 KiB

Open AccessArticle

Kinetic Studies and Moisture Diffusivity During Cocoa Bean Roasting

by Leydy Ariana Domínguez-Pérez, Ignacio Concepción-Brindis, Laura Mercedes Lagunes-Gálvez, Juan Barajas-Fernández, Facundo Joaquín Márquez-Rocha and Pedro García-Alamilla

Processes 2019, 7(10), 770; https://doi.org/10.3390/pr7100770 - 21 Oct 2019

Cited by 13 | Viewed by 5524

Abstract

Cocoa bean roasting allows for reactions to occur between the characteristic aroma and taste precursors that are involved in the sensory perception of chocolate and cocoa by-products. This work evaluates the moisture kinetics of cocoa beans during the roasting process by applying empirical [...] Read more.

Cocoa bean roasting allows for reactions to occur between the characteristic aroma and taste precursors that are involved in the sensory perception of chocolate and cocoa by-products. This work evaluates the moisture kinetics of cocoa beans during the roasting process by applying empirical and semi-empirical exponential models. Four roasting temperatures (100, 140, 180, and 220 °C) were used in a cylindrically designed toaster. Three reaction kinetics were tested (pseudo zero order, pseudo first order, and second order), along with 10 exponential models (Newton, Page, Henderson and Pabis, Logarithmic, Two-Term, Midilli, Verma, Diffusion Approximation, Silva, and Peleg). The Fick equation was applied to estimate the diffusion coefficients. The dependence on the activation energy for the moisture diffusion process was described by the Arrhenius equation. The kinetic parameters and exponential models were estimated by non-linear regression. The models with better reproducibility were the pseudo first order, the Page, and the Verma models (R² ≥ 0.98). The diffusion coefficients that were calculated were in the order of 1.26 to 5.70 × 10⁹ m s⁻² and the energy activation for moisture diffusion obtained was 19.52 kJ mol⁻¹. Full article

(This article belongs to the Section Advanced Digital and Other Processes)

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15 pages, 3715 KiB

Open AccessArticle

Effect of Initial Salt Composition on Physicochemical and Structural Characteristics of Zero-Valent Iron Nanopowders Obtained by Borohydride Reduction

by Denis Leybo, Marat Tagirov, Dmitry Arkhipov, Elizaveta Permyakova, Evgeny Kolesnikov and Denis Kuznetsov

Processes 2019, 7(10), 769; https://doi.org/10.3390/pr7100769 - 21 Oct 2019

Cited by 3 | Viewed by 3626

Abstract

The effect of initial salt composition on characteristics of zero-valent iron nanopowders produced via borohydride reduction was studied. The samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, and low-temperature nitrogen adsorption. The efficiency of Pb²⁺ ions removal from aqueous [...] Read more.

The effect of initial salt composition on characteristics of zero-valent iron nanopowders produced via borohydride reduction was studied. The samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, and low-temperature nitrogen adsorption. The efficiency of Pb²⁺ ions removal from aqueous media was evaluated. The use of ferric salts led to enhanced reduction kinetics and, consequently, to a smaller size of iron particles in comparison with ferrous salts. A decrease in the ionic strength of the synthesis solutions resulted in a decrease in iron particles. The formation of small highly-reactive iron particles during synthesis led to their oxidation during washing and drying steps with the formation of a ferrihydrite phase. The lead ions removal efficiency was improved by simultaneous action of zero-valent iron and ferrihydrite phases of the sample produced from iron sulphate. Full article

(This article belongs to the Special Issue Application of Advanced Oxidation Processes)

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25 pages, 1741 KiB

Open AccessFeature PaperArticle

Modeling and Observer-Based Monitoring of RAFT Homopolymerization Reactions

by Patrick M. Lathrop, Zhaoyang Duan, Chen Ling, Yossef A. Elabd and Costas Kravaris

Processes 2019, 7(10), 768; https://doi.org/10.3390/pr7100768 - 20 Oct 2019

Cited by 8 | Viewed by 3859

Abstract

Reversible addition–fragmentation chain–transfer (RAFT) polymerization of methyl methacrylate (MMA) is modeled and monitored using a multi-rate multi-delay observer in this work. First, to fit the RAFT reaction rate coefficients and the initiator efficiency in the model, in situ

^{1}

H nuclear magnetic resonance [...] Read more.

Reversible addition–fragmentation chain–transfer (RAFT) polymerization of methyl methacrylate (MMA) is modeled and monitored using a multi-rate multi-delay observer in this work. First, to fit the RAFT reaction rate coefficients and the initiator efficiency in the model, in situ

^{1}

H nuclear magnetic resonance (NMR) experimental data from small-scale (<2 mL) NMR tube reactions is obtained and a least squares optimization is performed.

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H NMR and size exclusion chromatography (SEC) experimental data from large-scale (>400 mL) reflux reactions is then used to validate the fitted model. The fitted model accurately predicts the polymer properties of the large-scale reactions with slight discordance at late reaction times. Based on the fitted model, a multi-rate multi-delay observer coupled with an inter-sample predictor and dead time compensator is designed, to account for the asynchronous multi-rate measurements with non-constant delays. The multi-rate multi-delay observer shows perfect convergence after a few sampling times when tested against the fitted model, and is in fair agreement with the real data at late reaction times when implemented based on the experimental measurements. Full article

(This article belongs to the Special Issue Computational Methods for Polymers)

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12 pages, 4237 KiB

Open AccessFeature PaperArticle

Comparison of Packed-Bed and Micro-Channel Reactors for Hydrogen Production via Thermochemical Cycles of Water Splitting in the Presence of Ceria-Based Catalysts

by Nonchanok Ngoenthong, Matthew Hartley, Thana Sornchamni, Nuchanart Siri-nguan, Navadol Laosiripojana and Unalome Wetwatana Hartley

Processes 2019, 7(10), 767; https://doi.org/10.3390/pr7100767 - 18 Oct 2019

Cited by 7 | Viewed by 4177

Abstract

Hydrogen production via two-step thermochemical cycles over fluorite-structure ceria (CeO₂) and ceria-zirconia (Ce_0.75Zr_0.25O₂) materials was studied in packed-bed and micro-channel reactors for comparison purposes. The H₂-temperature program reduction (H₂-TPR) results indicated [...] Read more.

Hydrogen production via two-step thermochemical cycles over fluorite-structure ceria (CeO₂) and ceria-zirconia (Ce_0.75Zr_0.25O₂) materials was studied in packed-bed and micro-channel reactors for comparison purposes. The H₂-temperature program reduction (H₂-TPR) results indicated that the addition of Zr⁴⁺ enhanced the material’s reducibility from 585 µmol/g to 1700 µmol/g, although the reduction temperature increased from 545 to 680 °C. Ce_0.75Zr_0.25O₂ was found to offer higher hydrogen productivity than CeO₂ regardless of the type of reactor. The micro-channel reactor showed better performance than the packed-bed reactor for this reaction. Full article

(This article belongs to the Special Issue Hydrogen Production Technologies)

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15 pages, 1408 KiB

Open AccessArticle

Absolute Stability Condition Derivation for Position Closed-Loop System in Hydraulic Automatic Gauge Control

by Yong Zhu, Shengnan Tang, Chuan Wang, Wanlu Jiang, Jianhua Zhao and Guangpeng Li

Processes 2019, 7(10), 766; https://doi.org/10.3390/pr7100766 - 18 Oct 2019

Cited by 27 | Viewed by 5386

Abstract

In the metallurgical industry, hydraulic automatic gauge control (HAGC) is a core mechanism for thickness control of plates used in the rolling process. The stability of the HAGC system’s kernel position closed-loop is key to ensuring a process with high precision, speed and [...] Read more.

In the metallurgical industry, hydraulic automatic gauge control (HAGC) is a core mechanism for thickness control of plates used in the rolling process. The stability of the HAGC system’s kernel position closed-loop is key to ensuring a process with high precision, speed and reliability. However, the closed-loop position control system is typically nonlinear, and its stability is affected by several factors, making it difficult to analyze instability in the system. This paper describes in detail the functioning of the position closed-loop system. A mathematical model of each component was established using theoretical analysis. An incremental transfer model of the position closed-loop system was also derived by studying the connections between each component. In addition, based on the derived information transfer relationship, a transfer block diagram of disturbance quantity of the system was established. Furthermore, the Popov frequency criterion method was introduced to ascertain its absolute stability. The results indicate that the absolute stability conditions of the position closed-loop system are derived in two situations: when spool displacement is positive or negative. This study lays a theoretical foundation for research on the instability mechanism of an HAGC system. Full article

(This article belongs to the Special Issue Smart Flow Control Processes in Micro Scale)

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16 pages, 5565 KiB

Open AccessFeature PaperArticle

Effects of a Dynamic Injection Flow Rate on Slug Generation in a Cross-Junction Square Microchannel

by Jin-yuan Qian, Min-rui Chen, Zan Wu, Zhi-jiang Jin and Bengt Sunden

Processes 2019, 7(10), 765; https://doi.org/10.3390/pr7100765 - 18 Oct 2019

Cited by 10 | Viewed by 3647

Abstract

The injection flow rates of two liquid phases play a decisive role in the slug generation of the liquid-liquid slug flow. However, most injection flow rates so far have been constant. In order to investigate the effects of dynamic injection flow rates on [...] Read more.

The injection flow rates of two liquid phases play a decisive role in the slug generation of the liquid-liquid slug flow. However, most injection flow rates so far have been constant. In order to investigate the effects of dynamic injection flow rates on the slug generation, including the slug size, separation distance and slug generation cycle time, a transient numerical model of a cross-junction square microchannel is established. The Volume of Fluid method is adopted to simulate the interface between two phases, i.e., butanol and water. The model is validated by experiments at a constant injection flow rate. Three different types of dynamic injection flow rates are applied for butanol, which are triangle, rectangular and sine wave flow rates. The dynamic injection flow rate cycles, which are related to the constant slug generation cycle time t₀, are investigated. Results show that when the cycle of the disperse phase flow rate is larger than t₀, the slug generation changes periodically, and the period is influenced by the cycle of the disperse phase flow rate. Among the three kinds of dynamic disperse flow rate, the rectangular wave influences the slug size most significantly, while the triangle wave influences the separation distance and the slug generation time more prominently. Full article

(This article belongs to the Special Issue Smart Flow Control Processes in Micro Scale)

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18 pages, 297 KiB

Open AccessFeature PaperArticle

LC-ESI-QTOF/MS Profiling of Australian Mango Peel By-Product Polyphenols and Their Potential Antioxidant Activities

by Danying Peng, Hafza Fasiha Zahid, Said Ajlouni, Frank R. Dunshea and Hafiz A. R. Suleria

Processes 2019, 7(10), 764; https://doi.org/10.3390/pr7100764 - 18 Oct 2019

Cited by 79 | Viewed by 7980

Abstract

Mango (Mangifera indica L.) is one of the most important fruits in the world. Mango peel is an important by-product that is rich in polyphenols and it could have high economic value if it is effectively utilized. Phenolic characterization is an essential [...] Read more.

Mango (Mangifera indica L.) is one of the most important fruits in the world. Mango peel is an important by-product that is rich in polyphenols and it could have high economic value if it is effectively utilized. Phenolic characterization is an essential step in the commercial utilization of mango peel by-products as food ingredients. Herein, qualitative and quantitative analyses of two Australian mango peel “Keitt” and “Kensington Pride” (K&P) by-products were conducted while using liquid chromatography coupled to electrospray ionisation and quadrupole time of flight mass spectrometry (LC-ESI-QTOF/MS) and high-performance liquid chromatography coupled to photodiode array detector (HPLC-PDA). A total of 98 polyphenols compounds were tentatively identified in both Keitt peel and K&P peel extracts, with greater concentrations of these compounds being detected in Keitt peel. The total phenolic content (TPC), total flavonoid content (TFC), and a total tannin content (TTC) were determined. The antioxidant activity of mango peel by-products was determined while using 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assay, ferric reducing antioxidant power (FRAP) assay, and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assay. Keitt peel contained higher concentrations of total phenolic compounds, flavonoids, and tannins and had higher antioxidant capacity in DPPH, FRAP, and ABTS assays as compared to K&P peel. In HPLC-PDA quantification, the predominant phenolic compounds in Keitt peel and K&P peel were catechin (62.32 ± 0.01 mg/g_d.w.) and syringic acid (17.78 ± 0.01 mg/g_d.w). Full article

(This article belongs to the Section Biological Processes and Systems)

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18 pages, 6231 KiB

Open AccessFeature PaperArticle

Energetic Analysis of Different Configurations of Power Plants Connected to Liquid Chemical Looping Gasification

by Mohammad mohsen Sarafraz, Mohammad Reza Safaei, Arturo S. Leon, Usama Khaled, Marjan Goodarzi and Rashed Meer

Processes 2019, 7(10), 763; https://doi.org/10.3390/pr7100763 - 18 Oct 2019

Cited by 15 | Viewed by 4338

Abstract

In this article, a thermodynamic study was conducted on the energetic and exergy performance of a new configuration of liquid chemical looping gasification (LCLG) plant integrated with a power block to assess the overall performance of the system including exergy partitioned in syngas [...] Read more.

In this article, a thermodynamic study was conducted on the energetic and exergy performance of a new configuration of liquid chemical looping gasification (LCLG) plant integrated with a power block to assess the overall performance of the system including exergy partitioned in syngas and first law efficiency (FLE). LCLG is a relatively new concept for the production of high-quality synthetic gas from solid feedstock such as biomass. As the temperature and pressure of the looping system are high, there is thermodynamic potential to co-produce chemical products, power and heat. Hence, in the present work, three different configurations of a power cycle were thermodynamically assessed. In the first proposed power cycle, the produced syngas from the gasifier was combusted in a combustion chamber and the exhausted gases were fed into a gas turbine. In the second and third proposed power cycles, the hot air was directly fed into a gas turbine or was used to produce steam for the steam turbine combined cycle. The processes were simulated with Aspen Plus and Outotec HSC chemistry software packages. The influence of different operating parameters including temperature and pressure of the air reactor and type of oxygen carrier on the first law and exergy efficiency (exergy partitioned in synthetic gas) was assessed. Results showed that the FLE for the proposed gas turbine and steam turbine combined cycles was ~33% to 35%, which is within the range of the efficiency obtained for the state-of-the-art power cycles reported in the literature. Results also showed that lead oxide was a suitable oxygen carrier for the LCLG system, which can be integrated into a steam turbine combined cycle with an FLE of 0.45, while copper oxide showed an FLE of 0.43 for the gas turbine combined cycle. Full article

(This article belongs to the Special Issue Thermodynamics: Modeling and Simulation)

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14 pages, 4452 KiB

Open AccessArticle

Preparation and Characterization of Porous Ti/SnO₂–Sb₂O₃/PbO₂ Electrodes for the Removal of Chloride Ions in Water

by Kangdong Xu, Jianghua Peng, Pan Chen, Wankai Gu, Yunbai Luo and Ping Yu

Processes 2019, 7(10), 762; https://doi.org/10.3390/pr7100762 - 18 Oct 2019

Cited by 14 | Viewed by 4293

Abstract

Porous Ti/SnO₂–Sb₂O₃/PbO₂ electrodes for electrocatalytic oxidation of chloride ions were studied by exploring the effects of different operating conditions, including pore size, initial concentration, current density, initial pH, electrode plate spacing, and the number of cycles. [...] Read more.

Porous Ti/SnO₂–Sb₂O₃/PbO₂ electrodes for electrocatalytic oxidation of chloride ions were studied by exploring the effects of different operating conditions, including pore size, initial concentration, current density, initial pH, electrode plate spacing, and the number of cycles. In addition, a physicochemical characterization and an electrochemical characterization of the porous Ti/SnO₂–Sb₂O₃/PbO₂ electrodes were performed. The results showed that Ti/SnO₂–Sb₂O₃/PbO₂ electrodes with 150 µm pore size had the best removal effect on chloride ions with removal ratios amounting up to 98.5% when the initial concentration was 10 g L⁻¹, the current density 125 mA cm⁻², the initial pH = 9, and the electrode plate spacing 0.5 cm. The results, moreover, showed that the oxygen evolution potential of 150 µm porous Ti/SnO₂-Sb₂O₃/PbO₂ electrodes was highest, which minimized side reactions involving oxygen formation and which increased the removal effect of chloride ions. Full article

(This article belongs to the Special Issue Electrolysis Processes)

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13 pages, 7195 KiB

Open AccessArticle

Suppression of Aluminum Dust Explosion by Ca(H₂PO₄)₂/RM Composite Powder with Core–Shell Structure: Effect and Mechanism

by Junfeng Wang, Xiangbao Meng, Ke Yan and Jinshe Chen

Processes 2019, 7(10), 761; https://doi.org/10.3390/pr7100761 - 18 Oct 2019

Cited by 32 | Viewed by 4382

Abstract

A Ca(H₂PO₄)₂/RM composite powder suppressant with core–shell structure was prepared with modified red mud (RM) as the carrier and Ca(H₂PO₄)₂ as the loaded particles, using a solvent–antisolvent process, in an attempt to [...] Read more.

A Ca(H₂PO₄)₂/RM composite powder suppressant with core–shell structure was prepared with modified red mud (RM) as the carrier and Ca(H₂PO₄)₂ as the loaded particles, using a solvent–antisolvent process, in an attempt to suppress aluminum dust explosion more effectively. The suppression effects of the Ca(H₂PO₄)₂/RM composite powder suppressant for aluminum dust flame propagation and for explosion overpressure were tested in a vertical glass tube test apparatus and a 20 L explosion vessel. The results show that the Ca(H₂PO₄)₂/RM composite powder suppressant was more effective in suppressing aluminum dust flame propagation and explosion overpressure than either Ca(H₂PO₄)₂ or RM powder alone. Finally, the suppression mechanism of the Ca(H₂PO₄)₂/RM composite powder suppressant was analyzed. On the one hand, a large amount of burning heat was absorbed through the decomposition of Ca(H₂PO₄)₂ and the melting phase transformation of the decomposition product; on the other hand, the strong isolation provided by the RM helped limit flame propagation. The strong adsorptivity of RM allowed this material to adsorb the radicals from the explosion reaction perfectly. Full article

(This article belongs to the Section Materials Processes)

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11 pages, 362 KiB

Open AccessFeature PaperArticle

Analysis of Inventory Turnover as a Performance Measure in Manufacturing Industry

by Jin Kyung Kwak

Processes 2019, 7(10), 760; https://doi.org/10.3390/pr7100760 - 17 Oct 2019

Cited by 20 | Viewed by 18209

Abstract

Using an appropriate measure to assess firms’ performance is essential. We analyzed inventory turnover (IT) as a performance measure in manufacturing processes because IT ratios are critical in the manufacturing industry and publicly available objective measures. Using the data of 421 manufacturing companies [...] Read more.

Using an appropriate measure to assess firms’ performance is essential. We analyzed inventory turnover (IT) as a performance measure in manufacturing processes because IT ratios are critical in the manufacturing industry and publicly available objective measures. Using the data of 421 manufacturing companies in Korea from 2010 to 2018, we conducted an extensive analysis of the factors affecting IT by segment and its correlation with other financial ratios. Then, we compare performances between the top and bottom companies determined by Altman’s Z score approach. We found that, for the overall manufacturing industry, IT ratios were negatively correlated with gross margin and debt cost, but positively correlated with capital intensity, although the results varied by segment. Moreover, IT ratios did not show significant correlations with other financial ratios categorized for growth, profitability, stability, productivity, and value of companies. However, adjusted IT (AIT) can be a good indicator of firms’ performance in terms of financial sustainability. Results also revealed that the top 10% companies showed higher AIT ratios than the bottom 10% in most segments of the manufacturing industry. The analysis of this study can be a starting point to search for a composite index to evaluate manufacturing processes comprehensively. Full article

(This article belongs to the Special Issue Performance Measurement and Optimization for Sustainable Production Processes Improvement)

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19 pages, 4367 KiB

Open AccessArticle

Arsenic Removal from Mining Effluents Using Plant-Mediated, Green-Synthesized Iron Nanoparticles

by Pari Karimi, Sepideh Javanshir, Mohammad Hossein Sayadi and Hoda Arabyarmohammadi

Processes 2019, 7(10), 759; https://doi.org/10.3390/pr7100759 - 17 Oct 2019

Cited by 43 | Viewed by 5178

Abstract

Arsenic contamination in industrial and mining effluents has always been a serious concern. Recently, nano-sized iron particles have been proven effective in sorptive removal of arsenic, because of their unique surface characteristics. In this study, green synthesis of iron nanoparticles was performed using [...] Read more.

Arsenic contamination in industrial and mining effluents has always been a serious concern. Recently, nano-sized iron particles have been proven effective in sorptive removal of arsenic, because of their unique surface characteristics. In this study, green synthesis of iron nanoparticles was performed using a mixed extract of two plant species, namely Prangos ferulacea and Teucrium polium, for the specific purpose of arsenic (III) removal from the aqueous environment. Results of UV-visible spectrometry, X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the formation of iron nanoparticles from Prangos ferulacea (Pf) and Teucrium polium (Tp) extracts. The synthesized Fe nanoparticles morphology was studied via microscopy imaging. The particle size was 42 nm, as assessed by dynamic light scattering (DLS) analysis. Adsorption experiments were also designed and performed, which indicated 93.8% arsenic removal from the aqueous solution at 200 rpm agitation rate, 20 min agitation time, pH 6, initial concentration of 0.1 g/L, and adsorbent dosage of 2 g/L. Adsorption isotherm models were investigated, and the maximum uptake capacity was determined to be about 61.7 mg/g. The kinetic data were best represented by the pseudo-second kinetic model (R² = 0.99). The negative value of Gibbs free energy, the enthalpy (−7.20 kJ/mol), and the entropy (−57 J/mol·K) revealed the spontaneous and exothermic nature of the adsorption process. Moreover, the small quantity of the activation energy confirmed the physical mechanism of arsenic adsorption onto iron nanoparticles and that the process is not temperature sensitive. Full article

(This article belongs to the Special Issue Advances of Nanocomposites in Bioremediation Processes)

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19 pages, 553 KiB

Open AccessFeature PaperArticle

An Optimal Feedback Control Strategy for Nonlinear, Distributed-Parameter Processes

by Debaprasad Dutta and Simant Ranjan Upreti

Processes 2019, 7(10), 758; https://doi.org/10.3390/pr7100758 - 17 Oct 2019

Cited by 3 | Viewed by 3380

Abstract

In this work, an optimal state feedback control strategy is proposed for non-linear, distributed-parameter processes. For different values of a given parameter susceptible to upsets, the strategy involves off-line computation of a repository of optimal open-loop states and gains needed for the feedback [...] Read more.

In this work, an optimal state feedback control strategy is proposed for non-linear, distributed-parameter processes. For different values of a given parameter susceptible to upsets, the strategy involves off-line computation of a repository of optimal open-loop states and gains needed for the feedback adjustment of control. A gain is determined by minimizing the perturbation of the objective functional about the new optimal state and control corresponding to a process upset. When an upset is encountered in a running process, the repository is utilized to obtain the control adjustment required to steer the process to the new optimal state. The strategy is successfully applied to a highly non-linear, gas-based heavy oil recovery process controlled by the gas temperature with the state depending non-linearly on time and two spatial directions inside a moving boundary, and subject to pressure upsets. The results demonstrate that when the process has a pressure upset, the proposed strategy is able to determine control adjustments with negligible time delays and to navigate the process to the new optimal state. Full article

(This article belongs to the Special Issue Process Systems Engineering à la Canada)

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17 pages, 2924 KiB

Open AccessArticle

Equilibrium and Kinetic Studies of Biosorptive Removal of 2,4,6-Trichlorophenol from Aqueous Solutions Using Untreated Agro-Waste Pine Cone Biomass

by Nadavala Siva Kumar, Mohammad Asif, Anesh Manjaly Poulose, Madala Suguna and Mansour I. Al-Hazza

Processes 2019, 7(10), 757; https://doi.org/10.3390/pr7100757 - 16 Oct 2019

Cited by 23 | Viewed by 3558

Abstract

The present work discusses the adsorptive removal of a phenolic pollutant, i.e., 2,4,6-trichlorophenol (TCP), using low cost untreated agricultural waste pine cone powder (PCP). The present biosorbent was thoroughly characterized with the help of FTIR, SEM, XRD, and CHN analysis. The presence of [...] Read more.

The present work discusses the adsorptive removal of a phenolic pollutant, i.e., 2,4,6-trichlorophenol (TCP), using low cost untreated agricultural waste pine cone powder (PCP). The present biosorbent was thoroughly characterized with the help of FTIR, SEM, XRD, and CHN analysis. The presence of amine (-NH₂), hydroxyl (-OH) and carbonyl (C=O) functional groups was detected by the FTIR analysis. The important biosorption factors like agitation time, biomass dosage, initial adsorbate concentration, and the initial pH were examined by batch studies. The biosorption kinetic process was fast, reaching equilibrium in 75 min. The experimental kinetic data revealed an excellent agreement with the pseudo second order (PSO) model. On the other hand, the Langmuir isotherm model best described the equilibrium data with the maximum biosorption capacity (q_max) of 243.90 mg/g. These values are better than the adsorption capacities of most agro-based untreated adsorbents previously reported in the literature. Owing to fast removal rates and high biosorption capacity, PCP can be used for cost-effective treatment of TCP from aqueous streams. Full article

(This article belongs to the Special Issue Advanced Liquid Waste and Gas Waste Treatment Processes)

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19 pages, 8021 KiB

Open AccessArticle

Effect of Pipe Diameter and Inlet Parameters on Liquid CO₂ Flow in Transportation by Pipeline with Large Height Difference

by Wei Lu, Hao Hu and Guansheng Qi

Processes 2019, 7(10), 756; https://doi.org/10.3390/pr7100756 - 16 Oct 2019

Cited by 14 | Viewed by 5181

Abstract

Fire prevention and extinguishing and CO₂ sequestration in coal mine gob require continuous transportation of liquid CO₂ in pipelines with large height difference (from ground to underground). However, the temperature and pressure variation of liquid CO₂ in pipelines with large [...] Read more.

Fire prevention and extinguishing and CO₂ sequestration in coal mine gob require continuous transportation of liquid CO₂ in pipelines with large height difference (from ground to underground). However, the temperature and pressure variation of liquid CO₂ in pipelines with large height difference is still unclear, which hinders the design of a liquid CO₂ pipeline transportation system. The influence of pipe diameter and inlet parameters (temperature and pressure) on the variation of temperature and pressure of liquid CO₂ along the 1000 m vertical pipeline was studied in this paper. The study found that for each pipeline diameter considered there existed a range of flowrates where safe flow conditions could be ensured, at which no phase transition occurs throughout the length of the pipeline. When the transporting flow is larger than the maximum limit flow, phase transition occurs dramatically, which will lead to a sudden drop in temperature and pressure. When the transporting flow rate is lower than the minimum limit flow rate, phase transition of CO₂ occurs slowly along the pipeline. According to the requirement of underground fire prevention and extinguishing for transporting flow rate and the economic cost of the pipeline system, the optimum diameter is 32 mm, and the corresponding safe transporting flow range is 507–13,826 kg/h. In addition, when the inlet pressure is constant, if the inlet temperature is too high, phase transition of CO₂ occurs dramatically at the entrance. For a 1000 m vertical pipe with diameter of 32 mm, when the inlet pressure is 14 bar, 16 bar, 18 bar, 20 bar, 22 bar, 24 bar, the corresponding maximum allowable inlet temperatures are −30 °C, −26 °C, −23 °C, −19 °C, −16 °C and −13 °C, respectively. This research has significant guidance for safety transportation scheme of liquid CO₂ from coal mine surface to underground. Full article

(This article belongs to the Section Environmental and Green Processes)

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15 pages, 1500 KiB

Open AccessFeature PaperArticle

Effect of Enzyme Interaction with Lignin Isolated from Pretreated Miscanthus × giganteus on Cellulolytic Efficiency

by Woochul Jung, Ratna Sharma-Shivappa and Praveen Kolar

Processes 2019, 7(10), 755; https://doi.org/10.3390/pr7100755 - 16 Oct 2019

Cited by 6 | Viewed by 3073

Abstract

The effect of binding between the lignin isolates from an alkali (NaOH)– and an acid (H₂SO₄)– pretreated Miscanthus and cellulolytic enzymes in Cellic^® CTec2 was investigated. Additonally, cellobiose and Avicel were enzymatically hydrolyzed with and without lignin isolates [...] Read more.

The effect of binding between the lignin isolates from an alkali (NaOH)– and an acid (H₂SO₄)– pretreated Miscanthus and cellulolytic enzymes in Cellic^® CTec2 was investigated. Additonally, cellobiose and Avicel were enzymatically hydrolyzed with and without lignin isolates to study how enzyme binding onto lignin affects its conversion to glucose. Three carbohydrate–lignin loadings (0.5:0.25, 0.5:0.5, and 0.5:1.0% (w/v)) were employed. The results indicated that β-glucosidase (BG) had a strong tendency to bind to all lignin isolates. The overall tendency of enzyme binding onto lignin isolate was similar regardless of pretreatment chemical concentration. Though enzyme binding onto lignin isolates was observed, hydrolysis in the presence of these isolates did not have a significant (p > 0.05) impact on glucose production from cellobiose and Avicel. Cellobiose to glucose conversion of 99% was achieved via hydrolysis at both 5 and 10 FPU/g carbohydrate. Hydrolysis of Avicel with 5 and 10 FPU/g CTec2 resulted in 29.3 and 47.7% conversion to glucose, respectively. Full article

(This article belongs to the Special Issue Bioenergy Systems, Material Management, and Sustainability)

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12 pages, 3629 KiB

Open AccessArticle

Arsenic Removal from Arsenopyrite-Bearing Iron Ore and Arsenic Recovery from Dust Ash by Roasting Method

by Rijin Cheng, Hua Zhang and Hongwei Ni

Processes 2019, 7(10), 754; https://doi.org/10.3390/pr7100754 - 16 Oct 2019

Cited by 23 | Viewed by 5278

Abstract

In most cases, arsenic is an unfavorable element in metallurgical processes. The mechanism of arsenic removal was investigated through roasting experiments performed on arsenopyrite-bearing iron ore. Thermodynamic calculation of arsenic recovery was carried out by FactSage 7.0 software (Thermfact/CRCT, Montreal, Canada; GTT-Technologies, Ahern, [...] Read more.

In most cases, arsenic is an unfavorable element in metallurgical processes. The mechanism of arsenic removal was investigated through roasting experiments performed on arsenopyrite-bearing iron ore. Thermodynamic calculation of arsenic recovery was carried out by FactSage 7.0 software (Thermfact/CRCT, Montreal, Canada; GTT-Technologies, Ahern, Germany). Moreover, the arsenic residues in dust ash were recovered by roasting dust ash in a reducing atmosphere. Furthermore, the corresponding chemical properties of the roasted ore and dust ash were determined by X-ray diffraction, inductively coupled plasma atomic emission spectrometry, and scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy. The experimental results revealed that the arsenic in arsenopyrite-bearing iron ore can be removed in the form of As₂O₃(g) in an air or nitrogen atmosphere by a roasting method. The efficiency of arsenic removal through roasting in air was found to be less than that in nitrogen atmosphere. The method of roasting in a reducing atmosphere is feasible for arsenic recovery from dust ash. When the carbon mass ratio in dust ash is 1.83%, the arsenic removal products is almost volatilized and recovered in the form of As₂O₃(g). Full article

(This article belongs to the Special Issue Process Modeling in Pyrometallurgical Engineering)

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16 pages, 349 KiB

Open AccessFeature PaperArticle

Surrogate Modeling for Liquid–Liquid Equilibria Using a Parameterization of the Binodal Curve

by Christian Kunde, Tobias Keßler, Steffen Linke, Kevin McBride, Kai Sundmacher and Achim Kienle

Processes 2019, 7(10), 753; https://doi.org/10.3390/pr7100753 - 16 Oct 2019

Cited by 10 | Viewed by 4410

Abstract

Computational effort and convergence problems can pose serious challenges when employing advanced thermodynamic models in process simulation and optimization. Data-based surrogate modeling helps to overcome these problems at the cost of additional modeling effort. The present work extends the range of methods for [...] Read more.

Computational effort and convergence problems can pose serious challenges when employing advanced thermodynamic models in process simulation and optimization. Data-based surrogate modeling helps to overcome these problems at the cost of additional modeling effort. The present work extends the range of methods for efficient data-based surrogate modeling of liquid–liquid equilibria. A new model formulation is presented that enables smaller surrogates with box-constrained input domains and reduced input dimensions. Sample data are generated efficiently by using numerical continuation. The new methods are demonstrated for the surrogate modeling and optimization of a process for the hydroformylation of 1-decene in a thermomorphic multiphase system. Full article

(This article belongs to the Special Issue Advanced Methods in Process and Systems Engineering)

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14 pages, 2089 KiB

Open AccessFeature PaperArticle

Conversion Technologies: Evaluation of Economic Performance and Environmental Impact Analysis for Municipal Solid Waste in Malaysia

by Rabiatul Adawiyah Ali, Nik Nor Liyana Nik Ibrahim and Hon Loong Lam

Processes 2019, 7(10), 752; https://doi.org/10.3390/pr7100752 - 16 Oct 2019

Cited by 13 | Viewed by 5911

Abstract

The generation of municipal solid waste (MSW) is increasing globally every year, including in Malaysia. Approaching the year 2020, Malaysia still has MSW disposal issues since most waste goes to landfills rather than being utilized as energy. Process network synthesis (PNS) is a [...] Read more.

The generation of municipal solid waste (MSW) is increasing globally every year, including in Malaysia. Approaching the year 2020, Malaysia still has MSW disposal issues since most waste goes to landfills rather than being utilized as energy. Process network synthesis (PNS) is a tool to optimize the conversion technologies of MSW. This study optimizes MSW conversion technologies using a PNS tool, the “process graph” (P-graph). The four highest compositions (i.e., food waste, agriculture waste, paper, and plastics) of MSW generated in Malaysia were optimized using a P-graph. Two types of conversion technologies were considered, biological conversion (anaerobic digestion) and thermal conversion (pyrolysis and incinerator), since limited data were available for use as optimization input. All these conversion technologies were compared with the standard method used: landfilling. One hundred feasible structure were generated using a P-graph. Two feasible structures were selected from nine, based on the maximum economic performance and minimal environmental impact. Feasible structure 9 was appointed as the design with the maximum economic performance (MYR 6.65 billion per annum) and feasible structure 7 as the design with the minimal environmental impact (89,600 m³/year of greenhouse gas emission). Full article

(This article belongs to the Special Issue Green Technologies: Bridging Conventional Practices and Industry 4.0)

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17 pages, 6959 KiB

Open AccessFeature PaperArticle

Theoretical and Experimental Insights into the Mechanism for Gas Separation through Nanochannels in 2D Laminar MXene Membranes

by Yun Jin, Yiyi Fan, Xiuxia Meng, Weimin Zhang, Bo Meng, Naitao Yang and Shaomin Liu

Processes 2019, 7(10), 751; https://doi.org/10.3390/pr7100751 - 15 Oct 2019

Cited by 36 | Viewed by 4622

Abstract

Clarifying the mechanism for the gas transportation in the emerging 2D materials-based membranes plays an important role on the design and performance optimization. In this work, the corresponding studies were conducted experimentally and theoretically. To this end, we measured the gas permeances of [...] Read more.

Clarifying the mechanism for the gas transportation in the emerging 2D materials-based membranes plays an important role on the design and performance optimization. In this work, the corresponding studies were conducted experimentally and theoretically. To this end, we measured the gas permeances of hydrogen and nitrogen from their mixture through the supported MXene lamellar membrane. Knudsen diffusion and molecular sieving through straight and tortuous nanochannels were proposed to elucidate the gas transport mechanism. The average pore diameter of 5.05 Å in straight nanochannels was calculated by linear regression in the Knudsen diffusion model. The activation energy for H₂ transport in molecular sieving model was calculated to be 20.54 kJ mol⁻¹. From the model, we can predict that the gas permeance of hydrogen (with smaller kinetic diameter) is contributed from both Knudsen diffusion and molecular sieving mechanism, but the permeance of larger molecular gases like nitrogen is sourced from Knudsen diffusion. The effects of the critical conditions such as temperature, the diffusion pore diameter of structural defects, and the thickness of the prepared MXene lamellar membrane on hydrogen and nitrogen permeance were also investigated to understand the hydrogen permeation difference from Knudsen diffusion and molecular sieving. At room temperature, the total hydrogen permeance was contributed 18% by Knudsen diffusion and 82% by molecular sieving. The modeling results indicate that molecular sieving plays a dominant role in controlling gas selectivity. Full article

(This article belongs to the Special Issue Gas Capture Processes)

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12 pages, 3031 KiB

Open AccessArticle

Joining of Al₂O₃ Rods Using Microwaves and Employing Sic Particles as Adhesive

by Natsuko Kimura, Takashi Fujii, Keiichiro Kashimura and Wataru Nakao

Processes 2019, 7(10), 750; https://doi.org/10.3390/pr7100750 - 15 Oct 2019

Cited by 1 | Viewed by 2666

Abstract

The joining of Al₂O₃ rods using SiC particles in a microwave field was examined. SiC with high microwave absorption characteristics is coated on the fracture surface of Al₂O₃ rods. Then, microwave irradiation is performed using a 2.45 [...] Read more.

The joining of Al₂O₃ rods using SiC particles in a microwave field was examined. SiC with high microwave absorption characteristics is coated on the fracture surface of Al₂O₃ rods. Then, microwave irradiation is performed using a 2.45 GHz single-mode cavity and the Al₂O₃ rods are rapidly joined. Energy dispersive X-ray spectroscopy reveals that the substance generated on the joining surface comprises Al and O. It is believed that the SiC interacts with the microwave to generate microwave plasma and that the plasma melts the Al₂O₃ rods. Thus, the matrix melts and the fracture surfaces are joined. Full article

(This article belongs to the Special Issue Microwave Heating and Chemistry )

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10 pages, 635 KiB

Open AccessArticle

Ultrasound-Assisted Phytochemical Extraction Condition Optimization Using Response Surface Methodology from Perlette Grapes (Vitis vinifera)

by Muhammad Kaleem, Asif Ahmad, Rai Muhammad Amir and Ghazala Kaukab Raja

Processes 2019, 7(10), 749; https://doi.org/10.3390/pr7100749 - 15 Oct 2019

Cited by 19 | Viewed by 3570

Abstract

In the current study, bioactive compounds of Vitis vinifera (Perlette) were extracted using an ultrasound-assisted extraction technique. The central composite design of response surface methodology (RSM) was used to determine the effect of time, temperature, and concentration of acetic acid on response variables [...] Read more.

In the current study, bioactive compounds of Vitis vinifera (Perlette) were extracted using an ultrasound-assisted extraction technique. The central composite design of response surface methodology (RSM) was used to determine the effect of time, temperature, and concentration of acetic acid on response variables that include extract yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of Vitis vinifera extracts. The results of the central composite design of RSM revealed that the quadratic polynomial model is best fitted to experimental results, with all the responses having a regression coefficient greater than 0.9. Optimized extraction levels include 26.5 min, an extraction temperature of 59 °C, and an acetic acid concentration of 62.9% with good extraction yield results of 34.95 g/100 g dry weight (DW) of grapes, TPC 34.38 mg gallic acid equivalent per gram (GAE/g) DW, flavonoid content 10.21 mg quercetin equivalents per gram (QEQ/g) DW, and antioxidant activity of 9.11 mg/100 mL ascorbic acid equivalent. The present study showed that acetic acid can be effectively used for the ultrasound-assisted extraction of polyphenols, flavonoids, and antioxidants of Vitis vinifera. These optimized conditions can be used for the extraction of bioactive compounds that can be for the development of nutraceutical products. Full article

(This article belongs to the Section Materials Processes)

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13 pages, 857 KiB

Open AccessFeature PaperArticle

Chromium VI and Fluoride Competitive Adsorption on Different Soils and By-Products

by Ana Quintáns-Fondo, Gustavo Ferreira-Coelho, Manuel Arias-Estévez, Juan Carlos Nóvoa-Muñoz, David Fernández-Calviño, Esperanza Álvarez-Rodríguez, María J. Fernández-Sanjurjo and Avelino Núñez-Delgado

Processes 2019, 7(10), 748; https://doi.org/10.3390/pr7100748 - 15 Oct 2019

Cited by 12 | Viewed by 2880

Abstract

Chromium (as Cr(VI)) and fluoride (F⁻) are frequently found in effluents from different industrial activities. In cases where these effluents reach soil, it can play an important role in retaining those pollutants. Similarly, different byproducts could act as bio-adsorbents to directly [...] Read more.

Chromium (as Cr(VI)) and fluoride (F⁻) are frequently found in effluents from different industrial activities. In cases where these effluents reach soil, it can play an important role in retaining those pollutants. Similarly, different byproducts could act as bio-adsorbents to directly treat polluted waters or to enhance the purging potential of soil. In this work, we used batch-type experiments to study competitive Cr(VI) and F⁻ adsorption in two different soils and several kinds of byproducts. Both soils, as well as mussel shell, oak ash, and hemp waste showed higher adsorption for F⁻, while pyritic material, pine bark, and sawdust had a higher affinity for Cr(VI). Considering the binary competitive system, a clear competition between both elements in anionic form is shown, with decreases in adsorption of up to 90% for Cr(VI), and of up to 30% for F⁻. Adsorption results showed better fitting to Freundlich’s than to Langmuir’s model. None of the individual soils or byproducts were able to adsorbing high percentages of both pollutants simultaneously, but it could be highly improved by adding pine bark to increase Cr(VI) adsorption in soils, thus drastically reducing the risks of pollution and deleterious effects on the environment and on public health. Full article

(This article belongs to the Special Issue Gas, Water and Solid Waste Treatment Technology)

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21 pages, 6157 KiB

Open AccessArticle

Design and Verification of a Single-Channel Pump Model based on a Hybrid Optimization Technique

by Jin-Hyuk Kim, Sang-Bum Ma, Sung Kim, Young-Seok Choi and Kwang-Yong Kim

Processes 2019, 7(10), 747; https://doi.org/10.3390/pr7100747 - 15 Oct 2019

Cited by 10 | Viewed by 3501

Abstract

This paper handles a hybrid multiple optimization technique to concurrently enhance hydraulic efficiency and decrease unsteady radial forces resulting from fluid-induced vibration of a single-channel pump for wastewater treatment. A single-channel impeller and volute was optimized systematically by using a hybrid particle swarm [...] Read more.

This paper handles a hybrid multiple optimization technique to concurrently enhance hydraulic efficiency and decrease unsteady radial forces resulting from fluid-induced vibration of a single-channel pump for wastewater treatment. A single-channel impeller and volute was optimized systematically by using a hybrid particle swarm optimization and genetic algorithm coupled with surrogate modeling. Steady and unsteady Reynolds-averaged Navier–Stokes analyses were conducted to optimize the internal flow path in the single-channel pump. Design variables for controlling the internal flow cross-sectional area of the single-channel impeller and volute in the single-channel pump were chosen to concurrently optimize objective functions with hydraulic efficiency and the unsteady radial forces resulting from impeller–volute interaction. The optimization results clearly showed that the arbitrary cluster optimum design considerably enhanced hydraulic efficiency and decreased the unsteady radial forces concurrently, compared to the reference design. Finally, the hydraulic performance of the optimized prototype model was verified experimentally. Then, it was proved that the proposed technique is a practical tool for designing a single-channel pump. Full article

(This article belongs to the Special Issue CFD Applications in Energy Engineering Research and Simulation)

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17 pages, 5485 KiB

Open AccessArticle

A Study of Cake Filtration Parameters Using the Constant Rate Process

by Faiz M. Mahdi, Timothy N. Hunter and Richard G. Holdich

Processes 2019, 7(10), 746; https://doi.org/10.3390/pr7100746 - 15 Oct 2019

Cited by 10 | Viewed by 19288

Abstract

The minerals calcium carbonate and talc were filtered under various conditions of filtrate flow rate and suspension concentration, using constant rate conditions with the aid of a peristaltic pump to draw the filtrate. Cake concentrations of between 0.41 and 0.53 v/v [...] Read more.

The minerals calcium carbonate and talc were filtered under various conditions of filtrate flow rate and suspension concentration, using constant rate conditions with the aid of a peristaltic pump to draw the filtrate. Cake concentrations of between 0.41 and 0.53 v/v for calcium carbonate and 0.19 and 0.26 v/v for talc were recorded. The mean sizes of the two different minerals were very similar, but the average specific resistances obtained from the experiments were 5.9 × 10¹⁰ and 7.4 × 10¹¹ m/kg for calcium carbonate and talc, respectively. These results do not agree with what would be predicted from an analytical equation for permeability, such as Kozeny-Carman. In addition, discontinuities were observed in all cases on the curves of filtrate volume with time for the initial stage of filtration. This behaviour is attributed to retarded packing compressibility (RPC) complicating the analysis of the filter medium resistance. RPC is an important component in determining the filter cake resistance and its functionality with cake forming pressure. It is found that there are additional effects that enhance the resistance to permeation in different cake materials, which is not recognised in the standard analytical approaches. These complexities can be related to shape, polydispersity, or agglomeration within the material sample and not to the experimental equipment or procedure. Furthermore, a complete and straightforward methodology is presented in this work for investigating the significance, or otherwise, of medium resistance on the later stages of the filtration. Full article

(This article belongs to the Special Issue Wastewater Treatment Processes)

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14 pages, 2795 KiB

Open AccessArticle

Optimization of Microwave Coupled Hot Air Drying for Chinese Yam Using Response Surface Methodology

by Hanyang Wang, Dan Liu, Haiming Yu, Donghai Wang and Jun Li

Processes 2019, 7(10), 745; https://doi.org/10.3390/pr7100745 - 15 Oct 2019

Cited by 19 | Viewed by 3555

Abstract

The effect of microwave coupled hot air drying on rehydration ratio (RR) and total sugar content (TSC) of Chinese yam was investigated. Single factor test and response surface methodology were used for process parameter optimization with hot air temperature, hot air velocity, slice [...] Read more.

The effect of microwave coupled hot air drying on rehydration ratio (RR) and total sugar content (TSC) of Chinese yam was investigated. Single factor test and response surface methodology were used for process parameter optimization with hot air temperature, hot air velocity, slice thickness, and microwave power density as variables and RR and TSC of dried products as responses. The effect of variables on RR followed the order: slice thickness > hot air temperature > microwave power density > hot air velocity. The effect of variables on TSC followed the order: slice thickness > microwave power density > hot air velocity > hot air temperature. The optimized process parameters were hot air velocity of 2.5 m/s, hot air temperature of 61.7 °C, slice thickness of 8.5 mm, and microwave power density of 5.9 W/g. Under the optimal conditions, the predicted values of RR and TSC were 1.90 g/g and 5.74 g/100 g, respectively, which is very close to corresponding actual values (1.83 g/g and 5.72 g/100 g). The desirability of 0.913 further validated the effectiveness of the model. The findings from this work may apply to other agricultural products. Full article

(This article belongs to the Section Process Control and Monitoring)

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