- Kenya
MOSES AROWO
Moi University, Chemical And Process Engineering, Faculty Member
This research article is a strategic and well holistic document to guide both national and county governments to achieve 100% energy access and prioritize sustainable energy transition besides creating many green jobs and enterprises. It... more
This research article is a strategic and well holistic document to guide both national and county governments to achieve 100% energy access and prioritize sustainable energy transition besides creating many green jobs and enterprises. It shall also form a very primary document and basis for every investor across the various opportunities and, in particular, energy generation and distribution. Energy is the prime engine of economic growth; its planning signals a direct positive impact on social welfare, economic activities, socio-political development, environmental sustainability. This article uses Low Emissions Analysis Platform (LEAP) software to provide the respective Medium-Term Plan (MTP) & Long-Term Plan (LTP) Update for the period 2019 (base year) to 2030. This MTP is the identification and analysis of suitable expansion paths of the country’s power system for that period, complying with the defined planning criteria and framework. This encompasses (i) examining of yesteryear electricity demand and advancement of future insistence scenarios; (ii) analysis of favorable expansion candidate fuels and technologies plus their scheduling; (iii) modeling of their anticipated addition to the prospective power generation and the expedient operation of the generation system for the year 2030. The key recommendation is that the Government of Kenya ought to determine means to sustainably expedite broad-based development in the MTP - implying stable and sufficient energy (including but not limited to grid electricity) supply to cater to growing demand.
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Gadam sorghum stalks are agricultural residues which can be hydrolyzed into fermentable sugars that can be used to produce bioethanol which is a renewable source of energy. In order to produce bioethanol from lignocellulosic biomass such... more
Gadam sorghum stalks are agricultural residues which can be hydrolyzed into fermentable sugars that can be used to produce bioethanol which is a renewable source of energy. In order to produce bioethanol from lignocellulosic biomass such as Gadam sorghum stalks, several processes including hydrolysis are involved. However, the use of lignocellulosic biomass for bioethanol production is hindered by the low yield of fermentable sugars obtained during hydrolysis. The lack of sufficient information on optimal conditions governing hydrolysis of lignocellulosic biomass leads to inefficient process which hinders the economic viability of large-scale bioethanol production. The objective of this study was to optimize reaction conditions involved in concentrated sulphuric acid hydrolysis of Gadam sorghum stalks. During hydrolysis, the conditions that were varied included temperature (40°C–80°C), time (30-90 minutes), and concentration of acid (30%-70%, w / w ). Central composite rotatable des...
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Sustainable sugarcane production and processing requires intensification of benefits and minimization of both short term and long term loses. Identification of long term loses/benefits from sugarcane production and processing is a... more
Sustainable sugarcane production and processing requires intensification of benefits and minimization of both short term and long term loses. Identification of long term loses/benefits from sugarcane production and processing is a difficult venture that entails critical scientific analysis based on collected scientific data, historical events and laboratory experiments. Moreover, most companies do not invest in research activities geared towards identifying critical long term loses or benefits. The long term effects of agronomic activities in sugarcane farming are herein discussed. Disposal of processed and unprocessed wastes from sugarcane production and processing activities are also discussed with various possible technical solutions and scientific techniques of effectively generating profits from such wastes summarized. It is hoped that the diverse green technologies of sugarcane production and processing explored herein can be of significant contribution to the management of th...
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Polyaniline (PANI) nanofibers with improved properties were prepared by high gravity chemical oxidative polymerization in a rotating packed bed with the assistance of p-aminodiphenylamine (AD) and p-phenylenediamine (AP), respectively.... more
Polyaniline (PANI) nanofibers with improved properties were prepared by high gravity chemical oxidative polymerization in a rotating packed bed with the assistance of p-aminodiphenylamine (AD) and p-phenylenediamine (AP), respectively. The effects of reactor type, additive dosage, reaction temperature and high-gravity level on the properties of products were investigated in detail. Three conclusions were made: (1) little amount of additive can significantly improve some properties of the nanofibers such as uniformity, specific surface area and specific capacitance; (2) in order to obtain high quality nanofibers, the high-gravity level should coordinate with the reaction rate; (3) the molecular weight and conductivity of PANI decrease with the increase of additive dosage. The products have larger specific surface areas of up to 73.9 and 68.4 m2/g, and consequently improved specific capacitance of up to 527.5 and 552 F/g for the PANI nanofibers prepared with AD and AP, respectively. H...
Research Interests: Chemical Engineering, Biochemistry, Physiology, Sociology, Materials Science, and 15 moreInorganic Chemistry, Hematology, Developmental Biology, Molecular Biology, Medicine, Multidisciplinary, Polymerization, Polyaniline, Nanofiber, AP, Capacitance, Oxidative phosphorylation, Langmuir, Interfacial Polymerization, and Ad
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The drying process is a significant step in the manufacturing process of enteric hard capsules, which affects the physical and chemical properties of the capsules. Thus, the drying characteristics of plant-based enteric hard capsules were... more
The drying process is a significant step in the manufacturing process of enteric hard capsules, which affects the physical and chemical properties of the capsules. Thus, the drying characteristics of plant-based enteric hard capsules were investigated at a constant air velocity of 2 m/s in a bench scale hot-air dryer under a temperature range of 25 to 45 °C and relative humidity of 40 to 80%. Results indicate that the drying process of the capsules mainly occur in a falling-rate period, implying that moisture transfer in the capsules is governed by internal moisture diffusion rate. High temperature and low relative humidity reduce drying time but increase the drying rate of the capsules. Investigation results of the mechanical properties and storage stability of the capsules, however, reveal that a fast drying rate leads to plant-based enteric hard capsules of low quality. Scanning electron microscopy further demonstrates that more layered cracks appear in capsules produced under a ...
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Oxygen is a harmful substance in many processes because it can bring out corrosion and oxidation of food. This study aimed to enhance the removal of dissolved oxygen (DO) from water by employing a novel rotor–stator reactor (RSR). The... more
Oxygen is a harmful substance in many processes because it can bring out corrosion and oxidation of food. This study aimed to enhance the removal of dissolved oxygen (DO) from water by employing a novel rotor–stator reactor (RSR). The effectiveness of the nitrogen stripping coupled with vacuum degassing technique for the removal of DO from water in the RSR was investigated. The deoxygenation efficiency (η) and the mass transfer coefficient (KLa) were determined under various operating conditions for the rotational speed, liquid volumetric flow rate, gas volumetric flow rate, and vacuum degree. The nitrogen stripping coupled with vacuum degassing technique achieved values for η and KLa of 97.34% and 0.0882 s−1, respectively, which are much higher than those achieved with the vacuum degassing technique alone (η = 89.95% and KLa = 0.0585 s−1). A correlation to predict the KLa was established and the predicted KLa values were in agreement with the experimental values, with deviations ge...
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Summary: The size of the dispersed phase was a key variable of the liquid-liquid heterogeneous flow system. In this work, the Sauter mean diameter (SMD) of the dispersed phase in a novel helical tube reactor (HTR) was evaluated by using a... more
Summary: The size of the dispersed phase was a key variable of the liquid-liquid heterogeneous flow system. In this work, the Sauter mean diameter (SMD) of the dispersed phase in a novel helical tube reactor (HTR) was evaluated by using a castor oil-water system. Experimental results showed that the SMD decreased with the increased Reynolds number and volumetric flowrate ratio of water to oil. The SMD in the HTR with vertical charging was smaller ion between calculated and experimental data was within ±20% than that with parallel charging. A dimensionless correlation of SMD in the HTR was proposed and the deviation between calculated and experimental data was within ±20%.
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The ozonation process of Bisphenol A (BPA) in a rotating packed bed (RPB) was modeled by response surface methodology (RSM) and artificial neural network (ANN). Experiments were performed according to the Box-Behnken design, and the... more
The ozonation process of Bisphenol A (BPA) in a rotating packed bed (RPB) was modeled by response surface methodology (RSM) and artificial neural network (ANN). Experiments were performed according to the Box-Behnken design, and the interactive effects of various parameters including ozone concentration, pH, rotation speed of RPB and liquid flow rate on BPA degradation efficiency were investigated. Ozone concentration and pH had the most significant interactive effects on BPA degradation efficiency while rotation speed of RPB had no significant interactive effects with other variables. A second order polynomial equation was obtained to predict BPA degradation efficiency. Also, a multi-layered feed-forward ANN model was constructed based on the data of RSM experiments. Six neurons in hidden layer had the highest correlation coefficient (RANN = 0.99158). A comparison between RSM and ANN models suggested that both can accurately predict BPA degradation efficiency (RRSM = 0.99559). The highest BPA degradation efficiency (99.52 %) was achieved under the conditions of ozone concentration of 20 mg L-1, pH of 11, liquid flow rate of 10 L h-1 and rotation speed of RPB of 800 rpm, which was well predicted by the RSM model (99.54 %) and the ANN model (99.82 %). However, the RSM model was slightly better than the ANN model owing to its higher determination coefficient (R2RSM = 0.9912, R2ANN = 0.9827) and lower mean square error (MSERSM = 0.0001684, MSEANN = 0.0003305).
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Abstract This work aimed to experimentally determine the effective gas-liquid specific interfacial area (ae) in a countercurrent flow rotor-stator reactor (RSR) by chemical absorption of CO2 into NaOH solution. The effects of different... more
Abstract This work aimed to experimentally determine the effective gas-liquid specific interfacial area (ae) in a countercurrent flow rotor-stator reactor (RSR) by chemical absorption of CO2 into NaOH solution. The effects of different operating parameters such as rotation speed, liquid volumetric flow rate and gas volumetric flow rate on ae were investigated. Results indicate that higher rotation speed, gas and liquid volumetric flow rates favor larger ae. A correlation to predict ae of gas-liquid phases in RSR is also established, and the predicted values are in agreement with the experimental data with deviations within 5 %.
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The work herein employed COMSOL Multiphysics simulation and experiment to study the temperature distribution of water in a specially designed cylindrical microwave (MW) reactor with two magnetrons....
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ABSTRACT This work studied the gas–liquid–liquid (G–L–L) reaction system of CO2 absorption into K2CO3/KHCO3 buffer solution enhanced by organic phase in a rotor–stator reactor (RSR). The effects of volume fraction of organic phase, type... more
ABSTRACT This work studied the gas–liquid–liquid (G–L–L) reaction system of CO2 absorption into K2CO3/KHCO3 buffer solution enhanced by organic phase in a rotor–stator reactor (RSR). The effects of volume fraction of organic phase, type of organic phase, rotational speed of RSR, gas and liquid volumetric flow rate, and temperature on CO2 absorption percentage were investigated. Results indicate that the addition of the organic phase with a volume fraction of 1.3–1.6% had significant promoting effect on CO2 absorption. CO2 absorption percentage increased with increase in the rotational speed of the RSR but decreased with rise in liquid temperature and gas–liquid ratio. This work demonstrates that RSR can significantly enhance liquid–liquid mixing and gas–liquid mass transfer processes in the G–L–L system.
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This study investigated the effect of different inorganic salts on treatment of simulated secondary effluent (SE) by ozone (O3) in a rotating packed bed (RPB) – (O3-RPB process), with Escherichia coliform (E. coli) and UV254 of fulvic... more
This study investigated the effect of different inorganic salts on treatment of simulated secondary effluent (SE) by ozone (O3) in a rotating packed bed (RPB) – (O3-RPB process), with Escherichia coliform (E. coli) and UV254 of fulvic acid as the indicators. The inactivation efficiency of E. coli and removal percentage of UV254 were studied under different rotation speeds of the RPB and varying concentrations of inorganic salts such as NaHCO3, Na2SO4 and CaCl2. Results indicate that both inactivation efficiency of E. coli and removal percentage of UV254 increased with an increasing rotation speed of the RPB but decreased with an increase in concentrations of the inorganic salts. Analyses on the mechanism of the treatment process reveal that the inorganic salts consume O3 and ·OH to generate products with lower oxidation ability, and thus result in a poor treatment effect of the effluent. This work provides fundamentals for the O3-RPB process in treatment of SE from urban wastewater ...
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Kenya is still faced with a number of technical, regulatory, institutional and financial challenges in her quest to fully develop and deploy solar electrification. A critical review of these challenges is therefore necessary in order to... more
Kenya is still faced with a number of technical, regulatory, institutional and financial challenges in her quest to fully develop and deploy solar electrification. A critical review of these challenges is therefore necessary in order to realize the numerous benefits associated with solar energy. This review focuses on four major aspects of solar electrification in Kenya: (i) the opportunities available for solar electrification (ii) the main barriers encountered in solar electrification (iii) government policies governing solar energy and (iv) the future panorama of solar energy space. A careful analysis of all of these aspects reveals that there are enormous solar energy market opportunities in Kenya with great potential for investment, poverty eradication, and sustainable economic development that can only be realized if the government fully enforces the existing energy policies, reforms energy subsidies, provides favorable tax holidays and implements net metering mechanism in the country.
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Only a third of the people living in Sub-Saharan Africa have access to electricity. While the benefits of electricity services for the society continue to increase, solar home system (SHS) provides a long-term rural electrification and... more
Only a third of the people living in Sub-Saharan Africa have access to electricity. While the benefits of electricity services for the society continue to increase, solar home system (SHS) provides a long-term rural electrification and development solution. SHS is thought out to be a robust and cost-effective option for supplying basic electrification under Kenya’s metrological conditions. This paper begins with an in-depth justification of the need for SHS in rural areas, and then it presents an overview of SHS financing, benefits and barriers, followed by a crucial component of existing SHSs in Kenya, Pay-As-You-Go (PAYG) technology. It ends with succinct analysis of the payment models highlighting the benefits, challenges and methods adopted in overcoming those challenges. Lessons from this review suggest that solar firms face a myriad of challenges operating in poor rural areas in Kenya; credit risk is a major concern for solar firms as well as financiers which makes payment models notably challenging. Technical performance of SHS is becoming well proven, and end users desire a wide range of component preferences and service levels that are of benefit. The challenges faced by solar firms using different payment models show that there is a dire need for integration of SHS with rural electrification policy in Kenya. The principal conclusion is that PAYG model offers the best option for SHS dissemination, though energy-as-a-service implementation has a great potential of improving the dissemination process in rural communities as it offers a promising mechanisms from a sustainability point of view.
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Abstract This study investigated mass transfer characteristics in a rotor–stator reactor (RSR) in terms of the overall volumetric mass-transfer coefficient (Kxa) using nitrogen stripping (N2–H2O–O2) and nitrogen stripping coupled with... more
Abstract This study investigated mass transfer characteristics in a rotor–stator reactor (RSR) in terms of the overall volumetric mass-transfer coefficient (Kxa) using nitrogen stripping (N2–H2O–O2) and nitrogen stripping coupled with vacuum degassing (vacuum–N2–H2O–O2) processes. Principal component regression (PCR) method was used to establish a mass transfer model, and the number of principal components (PCs) was examined by three different techniques including cumulative percent variance (CPV), average eigenvalue (AE), and cross validation (CV). The prediction performance of the PCR model was compared to that of the multiple linear regression (MLR) model. Results reveal that the number of PCs determined by CV based on the predicted residual error sum of squares can be used to determine the optimal number of PCs to express the relationship between various modeling variables and Kxa. The values of Kxa predicted by the PCR and MLR models in the N2–H2O–O2 system were in agreement with the experimental values with deviations within 15% while those in the vacuum–N2–H2O–O2 system generally agreed with the experimental values with deviations within 15% and 30%, respectively. These results indicate that the PCR method is best suited for mass transfer modeling in an RSR.
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This study investigated the absorption performance of CO2 into a diethylenetriamine (DETA)-based solution containing piperazine (PZ) or 1-(2-aminoethyl)piperazine (AEPZ) as an activator in a packed column with Dixon rings. The effects of... more
This study investigated the absorption performance of CO2 into a diethylenetriamine (DETA)-based solution containing piperazine (PZ) or 1-(2-aminoethyl)piperazine (AEPZ) as an activator in a packed column with Dixon rings. The effects of various operation conditions such as the activator concentration, gas flow rate, liquid flow rate, CO2 partial pressure, and solution temperature on overall gas-phase volumetric mass-transfer coefficient (KGav) were explored. Results indicate that the presence of PZ in DETA solution yields a better enhancement effect on KGav than AEPZ, and, thus, a combination of 5%PZ+25%DETA solution is expected to be a promising absorbent for CO2 absorption. The results further show that KGav increases with an increase in the liquid flow rate and a decrease in CO2 partial pressure and first increases and then decreases with an increase in solution temperature. On the other hand, the gas flow rate has an insignificant effect on KGav. A simplified empirical correlation for KGav as a funct...
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This work aimed to investigate the effectiveness of ozone in degradation of polyoxymethylene (POM) effluent in a rotating packed bed (RPB) (O3-RPB system). The degradation efficiency was evaluated in terms of chemical oxygen demand (COD),... more
This work aimed to investigate the effectiveness of ozone in degradation of polyoxymethylene (POM) effluent in a rotating packed bed (RPB) (O3-RPB system). The degradation efficiency was evaluated in terms of chemical oxygen demand (COD), 5-day biological oxygen demand (BOD5) and BOD5/COD under various operating conditions. Pilot experiments comprising the O3-RPB unit coupled with a biological contact oxidation unit were also carried out. The COD removal rates in the pilot process increased markedly to about 70-85% compared to about 40% in the original treatment process, which is the tertiary aerobic treatment in the plant, confirming that the O3-RPB system is very efficient in improving the biodegradability of the POM effluent.
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The work herein describes a novel technique, a rotating packed bed (RPB) combined with a charged device, to remove fine particles from gas steam. Experiments were carried out to investigate the effects of different operating conditions,... more
The work herein describes a novel technique, a rotating packed bed (RPB) combined with a charged device, to remove fine particles from gas steam. Experiments were carried out to investigate the effects of different operating conditions, including the packing type, packing thickness, rotation speed, gas–liquid volumetric ratio, initial fine particle concentration, and voltage, on the removal efficiency of fine particles from a gas stream. Results show that total removal efficiencies of fine particles and particles with a size of less than 2.5 μm (PM2.5) can reach up to 99 and 96%, respectively, under the operating conditions of packing thickness of 60 mm, rotation speed of 1000 rpm, gas–liquid volumetric flow ratio of 400, voltage of 40 kV, and use of a fine metal gauze packing. In addition, a correlation to predict PM2.5 removal efficiency was established, and results show that the predicted values of outlet PM2.5 concentrations are in agreement with experimental data, with deviations of ±20%. This work d...
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Abstract The shortage of low-sulfur coking coal will bring about an increasingly high hydrogen sulfide (H2S) in the coke oven gas (COG) in the near future. This work investigated the removal of hydrogen sulfide (H2S) from a simulated coke... more
Abstract The shortage of low-sulfur coking coal will bring about an increasingly high hydrogen sulfide (H2S) in the coke oven gas (COG) in the near future. This work investigated the removal of hydrogen sulfide (H2S) from a simulated coke oven gas (COG) by catalytic oxidative absorption in a rotating packed bed (RPB). Sodium carbonate (Na2CO3) solution doped with 20 mg L−1 of a commercial “888” catalyst was used as the absorbent. The removal efficiency of H2S was evaluated under various operating conditions including rotation speed of the RPB (N), liquid-gas ratio (L/G), inlet H2S concentration ( c H 2 S,in ), temperature (T) and Na2CO3 concentration ( c Na 2 CO 3 ) in an attempt to optimize the conditions. The results were validated by comparison with those of separate experiments conducted in a packed column comprising a high-efficiency laboratory packing of Dixon rings. The comparison results reveal that the RPB exhibited higher H2S removal efficiency than the packed column, indicating it as an efficient gas-liquid contactor with a greater potential to remove H2S from COG.
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Packing plays an important role on the mass transfer and mixing in a rotating packed bed (RPB) which is regarded as an important gas-liquid reactor or contactor for process intensification. Stainless steel wire mesh packing exhibits good... more
Packing plays an important role on the mass transfer and mixing in a rotating packed bed (RPB) which is regarded as an important gas-liquid reactor or contactor for process intensification. Stainless steel wire mesh packing exhibits good mass transfer performance when applied in a RPB. However, its construction repeatability and mechanical strength should be improved. Therefore, we introduced and designed a novel structured stainless steel wire mesh packing, aiming to overcome the above problems. In this work, the effective interfacial area (ae) in the packing and cavity zones of a RPB with four different types of structured stainless steel wire mesh packings was investigated at various rotational speeds, gas flow rates, and liquid flow rates by using a NaOH-CO2 mass transfer system. A brief analysis of the gas-liquid mass transfer interface area (A) and utilization ratio of packing’s specific surface area (wp) is presented. A modified correlation for the effective interfacial area in the packing zone of the RPB with structured stainless steel wire mesh packing was also proposed, and the predicted values were found to be in agreement with the experimental values with deviations generally within ±15%.
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This study employed a rotating packed bed (RPB) to enhance the absorption performance of nitrogen oxides (NOx) into sodium hydroxide (NaOH) solution with the preoxidation of NO by ozone. The absorption performance of NOx was evaluated in... more
This study employed a rotating packed bed (RPB) to enhance the absorption performance of nitrogen oxides (NOx) into sodium hydroxide (NaOH) solution with the preoxidation of NO by ozone. The absorption performance of NOx was evaluated in terms of its removal efficiency (η) from a gas stream under various operating conditions including O3/NOx molar ratio (MR), rotation speed of the RPB (N), liquid flow rate (L), NaOH concentration (CNaOH), inlet NOx concentration (CNOx), and using time (t). Also, the corresponding effect of adding oxidants (NaClO, H2O2, and KMnO4) and a reductant (CO(NH2)2) into the NaOH solution on NOx removal efficiency was investigated. Results indicated that preoxidation of NO by O3 significantly improved NOx removal efficiency and the removal efficiency increased with increasing O3/NOx molar ratio, NaOH concentration, and liquid flow rate but decreased with increase in inlet NOx concentration and using time. Additionally, NOx removal efficiency first increased and then decreased with ...
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Abstract A novel helical tube reactor (HTR) consisting of a pre-mixer and a helical tube was designed for mixing and reaction process intensification. The pre-mixer was used to adjust and change the premixing behavior between the involved... more
Abstract A novel helical tube reactor (HTR) consisting of a pre-mixer and a helical tube was designed for mixing and reaction process intensification. The pre-mixer was used to adjust and change the premixing behavior between the involved reactants, which eventually determines the environment for micromixing. Two types of pre-mixers, co-current flow pre-mixer (CCM) and cross-flow pre-mixer (CRM), were employed and their mixing performance was studied by computational fluid dynamics (CFD) simulations. Results revealed that the CRM has better mixing performance than the CCM, suggesting that the predicted micromixing efficiency of the HTR consisting of the CRM (CRM-HTR) may be better than that comprising the CCM (CCM-HTR). Furthermore, the iodide–iodate reaction system was used separately to characterize the micromixing efficiency of the HTR comprising the different types of pre-mixers, and the results are in agreement with those of CFD which predicted better micromixing performance in the CRM-HTR than the CCM-HTR. Additionally, the effects of feed position and initial dispersion size of acid solution, volumetric flow ratio, and viscosity on micromixing efficiency of the CRM-HTR were investigated. A comparison between the CRM-HTR and a straight tube reactor (CRM-TR) with a length equivalent to that of the CRM-HTR revealed that CRM-HTR has better micromixing efficiency. Moreover, the effects of curvature ratio and number of turns on micromixing efficiency of the CRM-HTR were also conducted. The results demonstrated that the curvature ratio had an important influence on the micromixing. This work shows that the novel CRM-HTR has great potential for chemical reaction process intensification.
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Abstract This work employed the electrical conductance and response time technique to experimentally investigate the hydrodynamic characteristics of a rotor-stator reactor (RSR). The effects of various operating conditions such as the... more
Abstract This work employed the electrical conductance and response time technique to experimentally investigate the hydrodynamic characteristics of a rotor-stator reactor (RSR). The effects of various operating conditions such as the rotation speed, liquid volumetric flow rate and number of rotor-ring layers on the hydrodynamic characteristics were examined, and correlations to predict the hydrodynamic characteristics of RSR were established. Results show that the predicted results are in agreement with those of the experiment with deviations within 10%, thus indicating the feasibility of employing the correlations to predict the liquid average velocity, holdup and number of liquid droplets in RSR.
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Abstract Computational fluid dynamics (CFD) is a powerful tool used to investigate the hydrodynamics in various chemical devices. As one of the typical process intensification equipment, rotating packed beds (RPBs) have been widely used... more
Abstract Computational fluid dynamics (CFD) is a powerful tool used to investigate the hydrodynamics in various chemical devices. As one of the typical process intensification equipment, rotating packed beds (RPBs) have been widely used in various fields. However, it is still a challenge to obtain the detailed information by CFD analysis due to the complex packing structure in the rotor of a RPB. In this study, we firstly built a three dimensional (3D) physical model with the same structure and size as the physical RPB and structured stainless steel wire mesh packing. The realizable k - e model is applied to investigate the gas pressure drop, pressure distribution, and gas flow at different rotational speeds and gas flow rates. Based on the breakdown of the overall gas pressure drop, the gas pressure drop in the inner cavity zone is the major contributor to the overall gas pressure drop under most operation conditions. The 3D physical model describing the actual RPB can give deep understanding of the gas flow in the entire RPB as well as the gas flow behavior around every fiber of the packing. Furthermore, one special phenomenon of strong turbulence, named as gas-side end effect, was revealed in the outer annular packing zone in the rotor.
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In this work, a novel helical tube reactor (HTR) was constructed, including a pre-mixer for adjusting the premixing behavior of reactants and a helical tube as a further mixing unit. The pre-mixer was modified to optimize the premixing... more
In this work, a novel helical tube reactor (HTR) was constructed, including a pre-mixer for adjusting the premixing behavior of reactants and a helical tube as a further mixing unit. The pre-mixer was modified to optimize the premixing behavior by using two methods, named as tangential-feeding and insertion of a helical baffle. The premixing behaviors were investigated via computational fluid dynamics (CFD) simulation. Simulation results indicated that both methods can change the fluid flow, enhance the turbulence kinetic energy, and improve the premixing performance in the pre-mixers. Based on the results of CFD simulation, it could be predicted that the micromixing efficiency of the HTR can be regulated by these methods accordingly. Then the predicated results were confirmed experimentally by a parallel competing reaction. Furthermore, the relationship between the premixing performance increasing and the corresponding micromixing efficiency increasing of the HTR was quantitatively analyzed. This article is protected by copyright. All rights reserved.
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This work employed a novel rotor-stator reactor (RSR) to intensify the degradation process of o-phenylenediamine (o-PDA) by ozone. The effects of different operating parameters including initial pH, temperature, rotation speed, liquid... more
This work employed a novel rotor-stator reactor (RSR) to intensify the degradation process of o-phenylenediamine (o-PDA) by ozone. The effects of different operating parameters including initial pH, temperature, rotation speed, liquid volumetric flow rate and inlet ozone concentration on the removal efficiency of o-PDA were investigated in an attempt to establish the optimum conditions. The removal efficiency was evaluated in terms of degradation ratio and chemical oxygen demand (COD) reduction ratio of the o-PDA wastewater. Results indicate that the removal efficiency decreased with increasing liquid volumetric flow rate but increased with an increase in pH and inlet ozone concentration. Also, the removal efficiency increased up to a certain level with an increase in rotation speed and temperature. Additionally, a comparison experiment was carried out in a stirred tank reactor (STR), and the results show that the degradation and COD reduction ratios reached a maximum of 94.6% and 6...
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This work investigated the degradation of methyl orange by ozone in the presence of ferrous and persulfate ions (O3/Fe(2+)/S2O8(2-)) in a rotating packed bed. The effects of various operating parameters such as initial pH, rotational... more
This work investigated the degradation of methyl orange by ozone in the presence of ferrous and persulfate ions (O3/Fe(2+)/S2O8(2-)) in a rotating packed bed. The effects of various operating parameters such as initial pH, rotational speed, gas-liquid ratio, ozone inlet concentration and reaction temperature on the degradation rate of methyl orange were studied with an aim to optimize the operation conditions. Results reveal that the degradation rate increased with an increase in rotational speed, gas-liquid ratio and ozone inlet concentration, and reached a maximum at 25 °C and initial pH 4. Contrast experiments involving ozone and ferrous ions (O3/Fe(2+)) were also carried out, and the results show approximately 10% higher degradation rate and COD removal in the O3/Fe(2+)/S2O8(2-) process than in the O3/Fe(2+) process. Additionally, the intermediates of the degradation process were analyzed to ascertain the degradation products.