Optimization Of Operating Conditions Research Articles

Numerical simulation and optimization of Pervaporation process based on Heat-Mass-Flow coupling

Pervaporation (PV) has the advantages of low energy consumption and high separation efficiency, but the trade-off effect between flux and separation factor restricts its large-scale application. Based on the conservation equations of mass, momentum and heat, a transient model of the whole PV process coupled with heat-mass-flow was established in this paper. The effects of feed temperature, feed concentration and feed flow rate on heat and mass transfer in PV process were analyzed. TEOS crosslinked PDMS/PTFE-PVDF membrane was prepared by scraping coating method. The reliability of the model was verified by taking n-butanol/water separation system as an example. The concentration polarization and temperature boundary layer under different operating conditions are discussed. The effect of operating conditions on the separation performance was evaluated by response surface method, and the optimal operating conditions are obtained. The results show that the concentration polarization of the membrane surface becomes more obvious with the increase of feed concentration. The temperature boundary layer decreases with the increase of feed flow rate. Surprisedly, there is a significant temperature gradient in the membrane, and the maximum temperature difference between the two sides of the membrane is as high as 1.02 K. Diffusion in the membrane is the rate controlling factor of PV process. The contribution of operating conditions to the separation performance is in the order of feed temperature > feed concentration > feed flow rate. The best operating conditions are: feed temperature 350.2 K, feed concentration 3.8 % n-butanol/water and feed flow rate 23.6L/h. This work provides a theoretical basis for the design of PV membrane materials and the optimization of PV operating conditions.

Method for assessing well interference at under-gas cap zone using CRM material balance model

Optimization of injection operation conditions is a primary task when designing the development of mature oil fields. To select optimal injectivities, solutions to the optimization problem based on a CRM (capacitance resistance model) analytical model are used. CRM models based on analytical solutions of the material balance equations of weakly compressible fluids due to their speed can be used as an alternative to flow simulation models in solving a number of problems to support oil field development. The main task of CRM models is to determine the well interference factor, i.e. the share of fluid produced due to a particular injection well. These factors can be used to analyze waterflooding and develop solutions for waterflood optimization. At the same time, in some cases reservoir fluids may have high gas content, which is a classical limitation of a CRM model and leads to underestimation of the interference factors when estimating the injection performance. In this paper, the authors propose an approach to solve the problems of distortion of such factors, and for the first time in CRM application practice a model has been adapted for use in the conditions of high GORs and has a potential for being applied for under-gas cap zones. This is achieved by including in the equations the physical properties of gas and their behavior under reservoir conditions. The complication of algorithms did not significantly affect the model run time, but allowed to match the model both separately and jointly for liquid and gas phases. Thus, the improved classical CRM model has significantly expanded the scope of application of operational waterflood analysis tools for assessing the current situation. No less complicated and urgent is the problem of forecasting the production of gas liberated in the conditions of the previously mentioned under-gas-cap zones, because it implies the need to estimate the future reservoir pressure. The authors intend to devote the next paper to finding a solution to this issue, taking into account the proposed new method of reservoir pressure estimation using a CRM model.

Intermittent investigations on attenuation mechanism of rechargeable zinc-air batteries during charge/discharge cycles.

Rechargeable zinc-air batteries (RZABs) are an ideal substitute for energy storage, but the short cycle longevity during long-term charge/discharge operation is one of the bottleneck factors that seriously restrict commercial application. Herein, the FeCo alloy/N, S co-doped carbon aerogel (NSCA/FeCo) were prepared as catalysts of cathode for RZABs. We investigated the polarization and impedance on long-term cycles during the battery operation to explore the attenuation mechanism. The results indicated that the roundtrip efficiency of batteries during charge/discharge cycles reduced fast initially and then slow. Besides, the comparative experiment was tested through the replacement of a new electrolyte and a zinc sheet. It is manifested that the failure of the battery is mainly due to the attenuation of the air cathode performance. Therefore, to further disclose the influencing factors and internal mechanisms of air cathode performance degradation, we conducted a series of characterization and testing, including the hydrophilicity, surface morphology, elemental composition, and electrochemical performance of three-electrode systems at different cycle times. This work not only provides a theoretical basis for deeply comprehending the attenuation mechanism of the cathode but also serves a reference for the material design and operating condition optimization of RZABs.

Re-evaluating the impact of feeding shock on anaerobic co-digestion of food waste and waste activated sludge: Trade-off between efficiency and stability

To optimize the feeding strategy of anaerobic digestion (AD) treating food waste and waste activated sludge, the impact of relative feeding shock (RFS) on the trade-off between efficiency and stability was re-evaluated at six feeding conditions from 1/96 (approximate continuous feeding) to 1. The results showed that increasing the RFS from 1/96 to 1/3 increased the CH4 yield from 293.23 mL CH4/g-total solid (TS) to the maximum value of 345.11 mL CH4/g-TS, which was due to the highest specific microbial growth rates (μmax) of acetate (1.05d-1) and propionate (0.48d-1) and a balanced reaction rate between acidogenesis and methanogenesis. However, when the RFS increased to 1, the total volatile fatty acids (TVFA) concentration increased from 0.51 to 5.90 g-COD/L, with the predominant VFAs changing from acetate to propionate, limiting methanogenesis. Meanwhile, the stability coefficient decreased to 0.37, leading to decreased CH4 yield and μmax. In addition, the high hydrogen partial pressure caused by high RFS increased the Gibbs free energy by 17 %, aggravating the thermodynamic disadvantages. The abundant methanogens shifted from Methanosaeta to Methanosarcina, which cooperated with a syntrophic partner-Syntrophomonas to ensure the smooth VFAs degradation at RFS of 1/3. These findings provide prima facie insights into the optimization of operational conditions for AD treating organic wastes.

Operating condition optimization of liquid metal heat pipe using deep learning based genetic algorithm: Heat transfer performance

Liquid metal heat pipes play a critical role in various high-temperature applications, with their optimization being pivotal to achieving optimal thermal performance. In this study, a deep learning based genetic algorithm is suggested to optimize the operating conditions of liquid metal heat pipes. The optimization performance was investigated in both single and multi-variable optimization schemes, considering the operating conditions of heat load, inclination angle, and filling ratio. The single-variable optimization indicated reasonable performance for various conditions, reinforcing the potential applicability of the optimization method across a broad spectrum of high-temperature industries. The multi-variable optimization revealed an almost congruent performance level to single-variable optimization, suggesting that the robustness of optimization method is not compromised with additional variables. Furthermore, the generalization performance of the optimization method was investigated by conducting an experimental investigation, proving a similar performance. This study underlines the potential of optimizing the operating condition of heat pipes, with significant consequences in sectors such as high temperature field, thereby offering a pathway to more efficient, cost-effective thermal solutions.

Interface engineering of Ce/La-doped hydrochar-supported nickel catalysts for enhanced tar reforming performance at low temperature

Catalytic reforming of biomass tar to syngas-especially under mild temperature-is an attractive albeit elusive route, necessitating the manufacture of highly efficient catalysts, in particular, from inexpensive, sustainable, and renewable resources as a prerequisite. Two interface-engineering strategies, including one-pot hydrothermal carbonization (HTC) approach and two-step HTC-impregnation method, were applied to fabricate a series of Ce/La-doped hydrochar-supported nickel catalysts, employing pinewood sawdust-derived hydrochar as the support, nickel as the active sites, and Ce or La as the promoter species. After the optimization of synthetic variables and operation conditions, the Ni0.1/Ce0.05-HC catalysts prepared by the two-step HTC-impregnation method simultaneously exhibited boosted activity, selectivity and recyclability than the Ni/HC counterpart without Ce addition as well as reported state-of-the-art catalysts in steam reforming of biomass tar at a low temperature of 600 °C. This exceptional catalytic performance was mainly attributed to the modulation of geometric structure and electronic structure of the exposed active sites by appropriate inclusion of cerium on the hydrochar-based nickel catalyst, which favored the water-gas shift, boudouard reaction and coke gasification, thereby imparting the materials with remarkable resistance against metal sintering and coke deposition during the steam reforming process. The result in this work underscores that the controlled interface between Ni species and hydrochar support by addition of Ce, which pertain to the hydrothermal processing technique, is a promising blueprint toward effective fuel production from waste biomass.

Multi-Factor Approach on How to Enhance the System Stability of CO2 Electrochemical Conversion to C2+ Products from Hours to a Month

Renewable electricity-powered electrochemical conversion of CO2 into fuels and value-added chemicals has immense potential to defossilize related sectors and provide an alternative storage solution for intermittent renewable energy supply. Studies show that low-temperature CO2 electrochemical conversion can be economically feasible if operated efficiently, particularly when the final price of electrolysis products and market size are attractive [1-2]. Cu is the only catalyst material that can reduce CO2 electrochemically into C2+ products (ethylene, acetate, n-propanol, propionate, propionaldehyde, and allyl alcohol) in significant amounts. Higher current densities (>200 mA/cm2) for the electrochemical reduction reaction of CO2 (CO2RR) on Cu-based gas diffusion electrodes (GDE) are already achieved; however, researchers still report a wide range of challenges, poor reaction stability being arguably the most critical one. To realize its full potential for large-scale industrial implementation, research efforts in both industry and academia focus primarily on selective catalysts, novel electrode designs, and cell design improvements, leaving a research gap for a multi-aspect approach centering on long-term stability.In our work, based on our own research and state-of-the-art knowledge, we focused on three main factors which play significant roles in the stability of Cu-based CO2RR: Cu surface restructuring, GDE flooding and liquid product accumulation in the electrolyte. These factors were addressed by taking various countermeasures, which mainly included changes in the electrode layer design, material selection in the electrode and cell, and optimization of numerous operation conditions.First, the Cu surface restructuring factor was considered in the multi-layered GDE design. Carbon-containing layers were used on top of the catalyst layer to stabilize otherwise agglomerating Cu catalysts as the literature [3-4] hypothesized. Secondly, the GDE flooding factor was counteracted with multiple measures: 1) PTFE material was chosen as the gas diffusion layer due to its electrical insulator feature as well as its electrochemical inertness. 2) GDE layers were prepared with polymers binders consisting of hydrophobic backbones with hydrophilic functional groups, controlling the water uptake in the layers. 3) Coexistence of potassium, carbonate, and bicarbonate ions in the catalyst and gas diffusion layer was inhibited by the layer design in which the binders had specific permeance for cations or anions (i.e., ion exchange ionomers), undermining the potassium carbonate and potassium bicarbonate salt formation inside the catalyst and gas diffusion layers. 4) Temperature was optimized to prevent the salt formation in the gas chamber of the cell. Third, liquid product accumulation in the electrolyte was determined to be a destabilizing factor for the GDE and the membrane separator as a result of a prior experimental study [5]. Therefore, the liquid products of CO2RR were prevented from accumulating in the electrolyte by periodical electrolyte refurbishment.After implementing all the identified countermeasures in Siemens Energy test rigs, we conducted a series of experiments focusing only on the system's stability. Internally designed 10 cm2 flow-cells, which had comparable cell architecture to the cell upscaled to 5000 cm2 scale in previous work [6], were employed combined with Cu-based GDEs as cathode and Ir-based anodes in this study. We have achieved 720 hours (one month) of stable CO2RR at 100 mA/cm2 at around 20% faradaic efficiencies for the aimed product, C2H4. Faradaic efficiency for all C2+ products was up to 50%. Increasing current densities from 100 mA/cm2 to 300 mA/cm2 compromised the stability while enhancing the C2+ selectivity. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101006701.

Optimal Design of Rotor Sails Based on Environmental Conditions and Cost

Rotor sails are one of the promising solutions to reducing the energy consumption and CO2 emissions of ships. Previous studies focused on how rotor sails affect ship dynamics and energy consumption. In the present study, an optimization-based workflow was proposed to find the optimal design of a rotor sail based on given environmental conditions for a target ship. Since the performance of a rotor sail depends on both operational conditions and the design of the rotor sail, a two-level optimization problem was proposed to separate the optimization of operational conditions and rotor sail design. At the operational level, the spin ratio of a given rotor sail was optimized at each time step under different environmental conditions. Then, the design of the rotor sail was optimized on the design level considering the initial cost of rotor sails and the average operational cost of the ship depending on the environmental conditions and their probabilities. The reductions in energy consumption of ships having optimal rotor sail designs, considering 5-year, 10-year, 15-year, and 20-year investment plans were found to be 0.34%, 2.7%, 3.91%, and 4.29%, respectively. When more severe environmental conditions were assumed for the 10-year investment plan, the diameter of the rotor sail increased and the reduction in energy consumption increased from 2.7% to 4.06%.

The Optimization of Operating Conditions in the Cross-Flow Microfiltration of Grape Marc Extract by Response Surface Methodology.

The recovery of valuable compounds like phenolic compounds and sugars from grape marc extracts implies different steps, including clarification. In this study, a response surface methodology (RSM) was used as a statistical tool to study the effects of operating conditions such as transmembrane pressure (TMP), temperature and feed flow rate on the performance of a microfiltration (MF) monotubular ceramic membrane with a pore size of 0.14 μm in the clarification of grape marc extract from the Carménère variety, as well to optimize the process conditions by implementing the Box-Behnken statistical design. The desirability function approach was applied to analyze the regression model equations in order to maximize the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose in the clarified extract. The optimal operating conditions were found to be 1 bar, 29.01 °C and 5.64 L/min. Under these conditions, the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose resulted in 65.78 L/m2h, 43.73 mg/L, 305.89 mg/L, and 274.85 mg/L, respectively.

Preparation of Adsorbent Materials from Rice Husk via Hydrothermal Carbonization: Optimization of Operating Conditions and Alkali Activation

Hydrothermal carbonization (HTC) of rice husk was optimized in terms of the adsorption capacity at equilibrium (qe) and hydrochar mass yield (MY). The studied variables were reaction temperature, residence time, and biomass-to-water ratio by means of response surface methodology. In both cases, reaction temperature resulted the most significant parameter promoting high qe values at higher temperatures when treating methylene blue (MB) as the target pollutant. Nevertheless, MY was low (~40%) when focusing on a possible industrial application. Hence, maximizing qe and MY simultaneously by optimization of multiple responses emerges as a promising solution to improve MY values (>60%) with no significant differences regarding the qe response. Furthermore, additional activation was conducted on optimal hydrochars to further investigate the enhancement of qe. As a result, no statistical differences between non-modified and activated hydrochars were observed for qe; however, the pseudo-second-order constant (k2) seemed to be increased after alkali activation, mainly due to a larger surface area. Non-modified and activated hydrochars were characterized via SEM, FTIR, XRD, and BET, resulting in two significant effects contributing to MB adsorption: increased surface area and functionalized hydrochar surface. Consequently, this work provides valuable insights on subsequent application of this HTC optimization scheme at an industrial scale.

Study on the Heat and Mass Transfer Characteristics of Humidifiers in Humidification–Dehumidification Desalination Systems

The humidifier plays a key role in a humidification–dehumidification (HDH) desalination system; it directly affects both the freshwater production efficiency and energy consumption ratio of the system. In this study, for a humidifier in an HDH system, a heat–mass coupled differential equation model of spray water and air on the surface of the packing material was established, and the effects of parameters such as the spray water temperature (tw), mass flow rate of spray water (mw), air temperature (ta), and air mass flow rate (ma) on the humidification performance of humidifiers composed of eight different types of packing materials were investigated. The results show the following: (1) Under the same inlet spray water and air conditions, the humidification performance of different packing materials from good to bad is as follows: cellulose paper, polypropylene, hackettes, saddles, snowflakes, wooden slats, polyvinyl chloride, gunny bag cloth. (2) Increasing the tw can significantly improve the humidification performance. To achieve higher humidification energy efficiency, it is recommended to increase the tw to above 80 °C. (3) With the increase in the mw, although the humidification efficiency (εhum) decreases slightly, the humidification rate (mhum) increases, and the specific humidification energy ratio (ηhum) decreases accordingly. To maintain a high mhum and a low ηhum, it is advisable to control the mw at not less than 0.5 kg/s. (4) Increasing the humidifier inlet ta can improve the mhum, εhum, and ηhum, although not as effectively as increasing tw. (5) Increasing the ma can improve mhum and εhum. However, it simultaneously increases the ηhum. The results of this study can provide theoretical guidance for the selection of efficient packing materials and the optimization of humidifier operating conditions in HDH desalination systems.

Performance optimization of solid oxide electrolysis cell for syngas production by high temperature co-electrolysis via differential evolution algorithm with practical constraints

Co-electrolysis of water and carbon dioxide using solid oxide electrolysis cell combined with the catalytic reactor to produce renewable synthesis fuel is considered as a promising strategy for carbon dioxide utilization. However, in order to achieve a target product with a remarkable system-level efficiency, a certain proportion of carbon monoxide and hydrogen from solid oxide electrolysis cell must be sent to the catalytic reactor directly, which imposes practical constraints on the solid oxide electrolysis cell performance. Take this constraint into consideration, we proposed a performance design methodology that enables a rapid and effective optimization of the solid oxide electrolysis cell operating conditions. Firstly, a physical model is developed by integrating chemical equilibrium, electrochemistry, and energy conservation involved in the solid oxide electrolysis cell. Secondly, a physical model is utilized to generate a dataset for the development of neural network model and optimization algorithm. This approach allows for the efficient determination of optimal conditions while considering practical constraints. In the case study, under the constraint that the desired fuel is a long carbon chain fuel with a carbon dioxide conversion rate ranging from 80 % to 90 %, the highest efficiency achieved by the solid oxide electrolysis cell is optimized to 66.75 %. Moreover, this approach is extended to other two target fuels (dimethyl ether and methane) under different carbon dioxide conversion rate, and the optimal performance is designed. According to the results, there is a trade-off between high efficiency and high carbon dioxide conversion rate, as the low carbon dioxide conversion rate often leads to higher efficiency. This method allows for flexible design of operating conditions to meet different fuel requirements and guide practical applications.

Modelling droplet size distribution in inline electrostatic coalescers for improved crude oil processing

Water-in-oil emulsions pose significant challenges in the petroleum and chemical industrial processes, necessitating the coalescence enhancement of dispersed water droplets in emulsified oils. This study develops a mathematical model to predict the evolution of water droplet size distribution in inline electrostatic coalescers (IEC) as a promising means to improve the water separation efficiency of current oil processing systems. The proposed model utilizes the population balance modelling approach to effectively simulate the dynamic and complex processes of coalescence and breakage of droplets in crude oil which directly influence the separation efficiency of the process. The method of classes as an effective mathematical technique is selected to solve the population balance equation (PBE). The accuracy of the model and considered assumptions agree well with experimental data collected from the literature. The results demonstrate the model's ability to accurately simulate droplet coalescence and breakage in emulsified oil while predicting droplet size distribution and water removal efficiency. The electric field strength, residence time, and fluid flow rate significantly influence the coalescence of droplets. At 4 kV and 5 m3/h after 4 s the mean diameter of droplets (D50) and separation efficiency reach the maximum of 94.3% and 432 µm, respectively. The model enables the optimization of operational conditions, resulting in increased performance and reliability of oil-processing systems while reducing the energy consumption and use of chemical demulsifiers. Additionally, utilization of the device in optimized conditions significantly reduces the size and weight of downstream separation equipment, which is particularly advantageous for heavy oils and offshore fields.

Experimental and Computational Fluid Dynamics Investigation on Tanning Process in a Rotating Drum

Mass transfer of chemicals greatly affects leather production efficiency and product quality. Leather shows different motions in a rotating drum during processing, which is strongly associated with chemicals’ mass transfer. However, how leather motions affect mass transfer remains unclear, which disfavors highly efficient leather manufacturing process. Here, different leather motion states were obtained by adjusting the drum rotation speed. Experimental results showed that the duration of leather rolling motion greatly increased by 41% when the rotation speed increased from 5 r/min to 20 r/min, and the uptake of the tanning agent was consequently improved, which indicated that the rolling motion is beneficial to mass transfer. Computational fluid dynamics simulation results showed that the mass transfer rate under rolling motion was higher than those under slipping, elevating and hanging motions, because the flow velocity and concentration gradient near the leather surface were higher under rolling motion. Accordingly, increasing the rolling motion enhanced the mass transfer in leather processing. This work identifies the leather motion beneficial for mass transfer and provides guidance on operating condition optimization and drum design for high-efficiency leather production.

Three-zone simulated moving bed for the separation of chlorogenic acid and caffeine fractions in the liquid extract of spent coffee grounds

Spent Coffee Grounds (SCG) is an agricultural residue obtained in a large quantity from local cafes in Thailand. In order to handle this waste effectively, the valorization of SCG is essential. SCG consists of beneficial phenolic compounds with antioxidative properties and caffeine, which can be recovered through extraction followed by separation and purification processes. In this work, water extraction of SCG was carried out. The volumetric composition of the liquid extract of SCG was then adjusted with an organic solvent, and the obtained mixture was used as the feed for subsequent separation. For the separation method of the SCG extract, a single chromatographic column was employed to separate a group of phenolic compounds (represented by chlorogenic acid) and a group of contaminants (represented by caffeine). The volumetric composition of the mobile phase was varied to determine the condition suitable for the separation of chlorogenic acid and caffeine in a C18 column. Adsorption parameters were determined and used to formulate the mathematical models describing the adsorption dynamics of those two bioactive compounds in the experimental breakthrough curves of standard solutions and the liquid extract of SCG. Furthermore, the three-zone simulated moving bed system (TZ-SMB) was designed to continuously separate fractions of chlorogenic acid and caffeine in the liquid extract of SCG. The adsorption parameters were employed in the optimization of TZ-SMB operating conditions using triangle theory, conducted via computer simulation. The experimental result of water extraction revealed that the yields of chlorogenic acid and caffeine were 0.292 and 0.583 mg/g dried SCG, respectively, using solid-to-liquid ratio of 1 g: 30 mL and temperature of 75 °C. The separation result in a single chromatographic column showed that the mobile phase consisting of acetonitrile, water, and formic acid (10: 90: 1.5 vol%) provided the linear adsorption isotherms for both chlorogenic acid and caffeine, and the chromatographic peaks of all compounds in the liquid extract of SCG were well separated. The simulated results of TZ-SMB at the optimal point revealed that the flow rates of desorbent, feed, extract product, and raffinate product were 0.626, 0.115, 0.081, and 0.593 mL/min, respectively, with the switching time of 20 min. At this point, the relative purities of caffeine in the extract product and chlorogenic acid in the raffinate product were 99.45 % and 98.88 %, respectively, with the maximum productivity of 0.045 mg/mL⋅h. In addition, for demonstration purposes, the lab-scale TZ-SMB experiment was conducted to show the separation of chlorogenic acid and caffeine in the liquid extract of SCG. The operating point from the triangle separation region was chosen based on the sensitivity of flow rate that ensured the criteria of purity. The experimental results showed that the relative purities of caffeine in extract product and chlorogenic acid in raffinate product were both 100 %, verifying the successful separation.

Catalytic Selective Oxidation of β-O-4 Bond in Phenethoxybenzene as a Lignin Model Using (TBA)5[PMo10V2O40] Nanocatalyst: Optimization of Operational Conditions.

The catalytic oxidation of phenethoxybenzene as a lignin model compound with a β-O-4 bond was conducted using the Keggin-type polyoxometalate nanocatalyst (TBA)5[PMo10V2O40]. The optimization of the process's operational conditions was carried out using response surface methodology. The statistically significant variables in the process were determined using a fractional factorial design. Based on this selection, a central circumscribed composite experimental design was used to maximize the phenethoxybenzene conversion, varying temperature, reaction time, and catalyst load. The optimal conditions that maximized the phenethoxybenzene conversion were 137 °C, 3.5 h, and 200 mg of catalyst. In addition, under the optimized conditions, the Kraft lignin catalytic depolymerization was carried out to validate the effectiveness of the process. The depolymerization degree was assessed by gel permeation chromatography from which a significant decrease in the molar mass distribution Mw from 7.34 kDa to 1.97 kDa and a reduction in the polydispersity index PDI from 6 to 3 were observed. Furthermore, the successful cleavage of the β-O-4 bond in the Kraft lignin was verified by gas chromatography-mass spectrometry analysis of the reaction products. These results offer a sustainable alternative to efficiently converting lignin into valuable products.

Techno-Economic Optimization of SOC Design and Operating Conditions in a Solid Oxide Fuel Cell-Gas Turbine Hybrid System

In a circular economy, highly efficient energy conversion systems are paramount to maximize resource utilization and minimize waste production, including carbon dioxide emissions. Solid oxide fuel cell-gas turbine hybrid systems, which can reach efficiencies of greater than 75%-LHV, have demonstrated to be a promising technology on the way to cleaner power generation. During the energy transition period, solid oxide fuel cell-gas turbine hybrid systems are likely to be operated on natural gas, however, their scalability allows these systems to reach very high efficiencies even at small scales, enabling the use of distributed resources such as biogas. In this presentation the authors will discuss key performance and economic metrics of small-scale (10 MW) advanced solid oxide fuel cell-gas turbine hybrid systems and their relation to cell design and system design elements. Current challenges in solid oxide fuel cell development include thermal cell management and production cost. This presentation presents findings of how cell design parameters influence thermal gradients and specific solid oxide cell costs on a $/kW-basis under hybrid system operating conditions. Moreover, specific cell components are identified, and effects will be discussed that can synergistically reduce thermal stress and specific cell cost at the same time. Informed by this analysis, the optimized cell design is integrated into a solid oxide fuel cell-gas turbine hybrid system in order to provide a comprehensive analysis of system operating conditions under consideration of thermal cell gradients, and new insights into economics and levelized cost of electricity are provided. The presentation will discuss the impact of fuel utilization, operating voltage, and operating pressure upon the heat integration, system’s operating window, and power output. A discussion of economic parameters will highlight cost driving factors to inform research on the next generation of solid oxide cells.

Recent Advances in Biomass Pyrolysis Processes for Bioenergy Production: Optimization of Operating Conditions

Bioenergy has emerged to be among the primary choices for the short- and medium-term replacement of fossil fuels and the reduction in greenhouse gas (GHG) emissions. The most practical method for transforming biomass into biofuel is thermochemical conversion, which may be broken down into combustion, torrefaction, pyrolysis, hydrothermal liquefaction, and gasification. In this study, producing biofuels using a biomass pyrolysis process was investigated. This study explored the pyrolysis process and operating conditions to optimize the process parameters to maximize the desired product yields and quality. The pyrolysis process produces three main products, which are bio-oil, bio-char, and gas. There are three classifications for the pyrolysis method, with each of them producing a majority of a certain product. First, slow pyrolysis is conducted in the temperature range of 300–950 °C and residence time of 330–550 s. It produces around a 30% oil yield and 35% char yield, and thus, the majority yield of slow pyrolysis is char. Second, fast pyrolysis produces around 50% oil, 20% char, and 30% gas yields with a temperature range of 850–1250 °C and a residence time of 0.5–10 s. The average yield of flash pyrolysis was found to be 75% bio-oil, 12% bio-char, and 15% gas, which is conducted within less than 1 s. It was reported that the pyrolysis of biomass was simulated using ASPEN Plus, where the effects of several parameters, such as the temperature, heating rate, and residence time, on the product yield and composition were investigated. Pyrolysis was performed under different conditions ranging from 400 to 600 °C. The effects of different catalysts on the pyrolysis process were studied. It was found that the addition of a catalyst could increase the yield of bio-oil and improve the quality of the product. The optimal operating condition for the pyrolysis process was determined to be a temperature of 500 °C, which resulted in a higher bio-oil yield. It was found that the biofuel yield was enhanced by selecting appropriate raw materials, such as rice husk, along with the pyrolysis temperature (e.g., 450 °C) and particle size (350–800 µm), and using a low residence time and pressure.

Performance map and operating condition optimization of industrial-size SOFCs using a PINN surrogate model

Solid Oxide Fuel Cell (SOFC) is an energy conversion technology featuring high efficiency, power density, durability, and fuel compatibility. In practice, however, SOFCs reach high power and high efficiency at different operating conditions. Hence, the optimal feasible operating condition is not straightforward and requires optimization.To resolve this problem, an accurate pretrained Physics-Informed Neural Network (PINN) model was developed as a surrogate of a 2D multi-physics model. For calibration, a planar SOFC with a 10 × 10 cm2 active area was tested at varied operating conditions. The resulting voltage error of the surrogate model was as low as 0.513%. The average runtime of the PINN model was 0.5 ms per case. Moreover, the PINN model accepts cell performance parameters as input and is therefore highly flexible.The surrogate was thereafter employed to generate performance maps that visualize the steady operating states at each combination of H2 flowrate and operating voltage. The voltages of peak power points and anode-safety boundaries were plotted as functions of H2 flowrate, so that the optimal operating conditions are shown graphically and can be tracked conveniently as the cell degrades.Further studies involving hydrocarbon fuels will be carried out in the future.

Supercritical CO2 Extraction of Seed Oil from Psophocarpus tetragonolobus (L.) DC.: Optimization of Operating Conditions through Response Surface Methodology and Probabilistic Neural Network

For the treatment of menopausal symptoms, nutraceuticals and herbal remedies are thought to be more natural and safer than hormones. Attention has been paid to the winged bean (Psophocarpus tetragonolobus (L.)) DC. seed oil. They are constituted of phytosterols, which may be effective in preventing menopausal symptoms. The purpose was to determine the optimal conditions for supercritical fluid extraction of oleic-rich oil from winged bean seeds. To optimize the condition, the response surface methodology (RSM) and probabilistic neural network (PNN) were utilized. In this research, PNN was used to improve RSM estimation by reducing the number of calculations. The optimized extraction conditions for winged bean seed oil entailed a CO2 flow rate of 21.3 L/h, a pressure of 30 MPa, a temperature of 55 °C, and an extraction time of 90 min. Under these conditions, the extraction process yielded a maximum oil yield of 36.27%. Ultimately, winged bean seed oil included a greater proportion of unsaturated fatty acids such as oleic acid, linoleic acid, and linoleic acid than oil produced using cold pressing or co-solvent extraction.