Inlet Feed Research Articles

Effect of geometric configuration on hydrodynamics, heat transfer and RTD in a pilot-scale biomass pyrolysis vapor-phase upgrading reactor

The effect of geometric configurations on flow hydrodynamics, heat transfer, and residence time distribution (RTD) in a pilot-scale biomass pyrolysis vapor phase upgrading (VPU) reactor is comprehensively studied by numerical simulations. More specifically, three types of carrier gas structure, three types of particle feed structure, and five types of outlet structure are included in the present study. The results demonstrate that the effect of geometric configurations on heat transfer and RTD is much more pronounced than that on flow hydrodynamics such as the axial particle distribution, probably due to the low particle inventory. In this case, it is necessary to verify the difference of the temperature field in the grid independence analysis in addition to flow dynamics. Furthermore, we find that the carrier gas inlet and particle feed have an important influence on the particle distribution at the bottom of the reactor and thus affect the back-mixing behavior at both the bottom and outlet. As a consequence, such back-mixing flows further affect the temperature field and RTD substantially. Moreover, reducing the abrupt structure contributes to the catalyst particles well-distributed at the bottom of the reactor. This can reduce the mean residence time and variance, thereby decreasing the particle and gas temperature in the reactor. This work has a potential to provide a feasible guideline for biomass pyrolysis VPU reactor design and optimization.

Effect of Bacillus spp. strains on wheat nutrient assimilation and bioformulation by new spray drying approach using natural phosphate powder

The present work is aiming to propose a new formulation of Bacillus spp. strains in combination with natural phosphate by spray drying. Bacillus sp. strain (SS0306) has proven its plant growth promoting effectiveness mainly on phosphate solubilization capacity and improved nutrient assimilation in wheat plants. Bacterial microencapsulation methods involved spray-drying assays that were conducted using 5% of rock phosphate with 2%–10% of maltodextrin and 2% of alginic acid sodium salt. The process parameters were also optimized with inlet temperature (155 °C), feed rate (9 min mL−1), and spray air rate (413.87 L h−1). Results showed a moisture content of the dried powders ranged between 2% and 8% and satisfactory viability levels of Bacillus sp. SS0306 (105–106 CFU g−1) after drying assay, with the survival rates between 61.56% and 64.18%. Optimized process reached 50.30% and 65.10% for the product yield, with 1.25 ± 0.006 mg g−1 of higher Pi content observed in rock phosphate formulations based on Alg 2%. The present study opens new possibilities to develop Bio-mineral fertilizers using the spray drying approach.

Experimental and simulation study of multichannel air gap membrane distillation process with two types of solar collectors

Solar thermal energy for membrane distillation desalination is a green and safe way for areas where water scarcity and solar irradiance are strongly correlated. In this paper, a commercial-scale of desalination plant was installed and tested to study the performance of a multichannel spiral-wound air gap membrane distillation module with an area of 14.4 m2. Air gap membrane distillation desalination plant at Port Said university was powered by solar energy using flat plate and evacuated tube collectors. The model validation was carried out. The solar desalination systems were numerically simulated using the program TRNSYS under different weather conditions throughout the year. The influence of the main operating parameters (feed flow rate and inlet temperatures of evaporator and condenser) was investigated. Regression analysis agreed with experimental data fitting using a quadratic polynomial model with coefficients of determination (R2) values of 0.997, 0.972, and 0.999 for permeate flux, outlet feed temperature, and outlet coolant temperature, respectively. The results showed that the permeate flux of the air gap membrane distillation with the evacuated tube collectors was 18.81%–30.44% higher than flat plate collector, and its cost was 22.48% lower. The specific thermal energy consumption of the air gap membrane distillation system ranged from 158.83 kWh/m3 to 346.55 kWh/m3. The maximum gain output ratio reaches 4.4 at 52 °C, depending on the feed inlet temperature. The thermal efficiency of the air gap membrane distillation system is 72%. The proposed air gap membrane distillation system produced 28.78 m3/year of fresh drinking water at a cost of USD 14.73/m3 with remarkable reducing in carbon dioxide emissions by 7,274.45 kg/year.

Fine powder of lipid microparticles – spray drying process development and optimization

ObjectivesPerformed studies were focused on developing spray drying technique for aqueous dispersion of solid lipid microparticles (SLM) by selecting appropriate process parameters and assessing their impact on the process and properties of the obtained dry SLM powders. SignificanceSpray drying allows to obtain SLM in a dry powder form when the liquid form does not present sufficient long-term stability (e.g. due to degradation of the active substance or aggregation of particles) or when the dosage form is to be used in a fine powder form. MethodsIn the first stage of research the experiments were designed to optimize process parameters during spray drying of the placebo SLM dispersions prepared with two lipids: Compritol or stearic acid. The inlet temperature and feed rate were process parameters selected for monitoring. As response values, yield and quality attributes of the final product, namely particle size, moisture content and powder flowability were chosen. The process parameters optimized in the first step were then used to dry the SLM with model active substances: cyclosporine and spironolactone. ResultsThe use of 3D surface charts, developed on the basis of the results of the conducted experiments, allowed for the selection of optimal process conditions for obtaining final product with desired properties and satisfying yield. For SLM with Compritol these were: inlet temperature 90 °C and feed rate 2.4 ml/min; whereas for SLM with stearic acid 80 °C and 3 ml/min were optimal, respectively. Process parameters optimized for placebo formulations were found to be equally suitable for drying drug-loaded SLM. ConclusionsThe spray drying was found to be an effective method of obtaining dry powders from aqueous SLM dispersions. The lipid forming the SLM matrix should be considered the most important factor on which the process parameters depend. The most appropriate drying conditions selected during drying placebo formulations proved to be equally effective when SLM with the same composition and with model active substance were subjected to drying.

Energy, exergy and exergoeconomic (3E) analysis and multi-objective optimization of a closed-circuit desalination system with side-conduit

Membrane desalination technologies such as reverse osmosis (RO) are being widely used around the world to deal with the growing freshwater shortage. In addition, the use of new reverse osmosis technologies that improve the performance of traditional ones, has received more attention. The main problem in desalination plants is the high total specific energy consumption as well as high capital investment, maintenance and repair costs. In this study, the performance of a new closed-circuit reverse osmosis (CCRO) desalination system with side-conduit as a replacement for energy recovery device, is investigated based on energy, exergy and exergoeconomic (3E) analysis. 3E analysis is performed based on four important factors including 1) concentration of inlet feed water 2) number of cycles 3) osmotic pressure 4) mass flow rate of feed water. Then, using the output data obtained from 3E analysis, the optimal points for six key parameters of exergy efficiency, net driving pressure (NDP), total unit cost product (SUCP), mass flow rate of permeate, recovery ratio and specific energy are determined through multi-objective optimization. The simulation results show that in the proposed system, by increasing the number of cycles, the recovery ratio increases while the system costs also increase due to increase in pressure and concentration of inlet feed. It is found that the optimal recovery ratio of 64.29% is obtained for 9th cycle and inlet feed concentration of 6.95% and the optimal specific energy consumption of 2.5 kWh/m3 is obtained for 7th cycle and inlet feed concentration of 6.07%.

Retrofit design of an industrial natural gas liquids recovery process based on the pinch technology concept

Energy consumption is increasing very rapidly, especially in the high-energy consuming industries such as oil, gas, and Natural Gas Liquids refineries. Pinch analysis as a well-established and successful technique is used to improve the energy efficiency of the above-mentioned plants. However, the limitations on ΔTmin and those related to the technical and economic aspects result in the lack of capability by the pinch analysis in reducing the utility beyond a specific amount. Also, this analysis only uses the existing process streams and cannot identify and develop high potential streams reducing the external utility consumption. Opportunities for saving energy consumption would increase through the self-refrigeration methods, and they further decrease the utility consumption. Moreover, for minimizing the process changes, the Heat Exchanging Network should be optimized by pinch analysis and then, the opportunities for self-refrigeration of the process should also be challenged. Thus, the present study was conducted to consider the opportunities for reducing the energy consumption and the required utility in a real-life case study of a Natural Gas Liquids plant. Finally, the heat exchanging network redesigned by the grass root plant was revamped with side streaming from the demethanizer column by changing the ΔTmin to 3 °C resulting in the provision of an additional refrigeration stream for inlet feed instead of external utility. This scheme resulted in saving 3671 kW of refrigeration compressors shaft work and saving 6100 kW of the needed energy for the reboiler and condenser. As the result, 546 kW (53 %) of the plant's total energy consumption will be saved by the pinch and self-refrigeration scheme. The total savings in the purchased equipment costs and operating costs saving of the NGL plant are equal to 3,891,560 (USD) and 3,757,451 (USD/year), with 378 days' payback period.

Effect of the spray drying conditions on the physicochemical and structural characteristics and the stability of chia oil microparticles

AbstractChia oil has a high content of linolenic and linoleic acids, which are essential for the human body. However, their high degree of unsaturation (double bonds) makes the oil very susceptible to oxidation. In this context, the use of spray drying can be useful strategy to minimize the oxidation of this oil. Thus, the aim was to assess the effects of inlet temperature and feed rate conditions involved in the spray drying process on the physicochemical and morphological characteristics, and stability of the chia oil microparticles with maltodextrin and GA. The microparticles were obtained with a yield of 50%, encapsulation efficiency greater than 87%, low‐moisture content, and mean particle sizes ranging from 3.01 to 4.11 μm. The thermal evaluation and storage evidenced an increase in stability. The 1H HR‐MAS NMR technique showed that the microparticles maintained the characteristic fatty acid profile of chia oil and seeds. Results indicate that the microencapsulation methodology was suitable for preparing microparticles containing chia oil.

Surface fat and insolubility of whole camel milk powders as affected by spray drying operating parameters

Face centered central composite design was used to investigate the effect of spray drying process parameters (inlet temperature, atomization pressure and feed flow rate) on selected quality parameters of whole camel milk. During storage by freezing, the integrity of camel milk fat globules is maintained with observed aggregation. Whole camel milk contains 12.18% total solids, 3.5% protein and 3.99% [w/w] lactose whereas for the powders, the total solids content was in the range of 94–97%, protein 22–29% and lactose 27–31% [w/w]. By combining response surface methodology with desirability function, the spray drying process of whole camel milk was optimized with objectives of maximizing the yield and minimizing undesired quality degradation parameters. Consequently, it was possible to recover 62% of total solids without affecting the desired aspects of the final physico-chemical properties of powders (minimum insolubility index of 0.1 mL and surface fat content of 4.2% [w/w]) with targeted final moisture content of 4.5% [w/w]. These properties would make the powders safe during extended period of storage.

Effects of Feeding Mode and Inlet Area Ratio on Heating Characteristics in Dual-Inlet Swirl Tubes

A preheating exchanger is developed for improving acidic water degassing. Reasonable optimization of dual-inlet swirl heating tubes is analyzed by computations of the flow and heat transfer. The comparisons of the swirl number and circumferential average Nusselt number between isobaric injection and isokinetic injection are performed. Inlet area ratios ranging from 0.1 to 0.9 exhibit an important influence on the flow phenomena and the heating performance. A lower value of inlet area ratio leads to the tendency for the fluid passing through inlet 2 to move upstream of inlet 2 and results in more vortex pairs between inlets 1 and 2. An inlet area ratio value of 0.5 exhibits the largest global average Nusselt number, normalized Nusselt number, and thermal performance factor. The optimized inlet area ratio is suitable for improving the degassing efficiency.

Simulation of water recovery in membrane condenser dehumidification process

Abstract The high humidity gas dehumidification process and water recovery characteristics in the membrane condenser (MC) were investigated with numerical simulation method in this paper. Different from the traditional condensation process, the hydrophobic porous membrane was utilized for water gases separation. The transmembrane pressure difference was considered as a supplement to the driving force of temperature difference. Results indicate that the porous surface has a positive effect on the high humidity gas dehumidification. It is important to note that water recovery tends to increase and then decrease with inlet feed flow rate increasing from 0.12 L/min to 0.6 L/min. The sweep flow rate ranging from 0.094 L/min to 0.885 L/min were considered. The optimal flow rate ratio between sweep side and feed side is 0.281 for the single-pipe model. It is found that increasing the inlet feed flow temperature from 315 K to 335 K can improve the water recovery over 20%. Additionally, water recovery reduces significantly with the increase of transmembrane flux, for the transmembrane gas reduces the transmembrane temperature difference while increasing the perturbation. These findings would provide important references in using hollow fiber MC for water recovery from high humidity gas.

Adaptive MPC Controller based Cascade Control of Distillation Column Parameters Estimation and Optimization

One of the key element of many industrial process plants is a crude oil distillation system. This system requires heat for the vaporization of a mixture of feed to the distillation column in vapor form. In the existing process of distillation, an abnormal change of heat is exhibited due to improper control and monitoring of disturbances affecting the plant. This would result for undesired loss of product and product purity to be reduced. The parameters that are expected to be considered in the analysis, model and control of a distillation system described under the proposed study are inlet feed temperature, distillation column temperature, feed composition, internal liquid and vapor composition, feed flow rate, reboiler temperature and an external reflux temperature to the distillation tower. Controlling distillation column parameters with Adaptive model predictive control allows for the determination of the predicted future instant values of the plant outputs. Using such control technique, the controlled plant outputs such as the temperature of distillation column, feed preheater, re boiler and the upper reflux is properly controlled and their parameters are estimated using recursive least squares approach in the entire process adaptation mechanism. From the analysis and optimization work made on the proposed system, the efficiency of the plant outputs in tracking their corresponding set point has improved based on the value of the transient system parameters as well as the value of relative volatility of feed mixture to the column. As per the finding in the analysis of the process, 95.4% and 93.5% improvement on the set point tracking and to amount of evaporation liquid feed has been obtained respectively. On the other hand an improvement on transient parameters has been achieved to all plant outputs. As per the result obtained from the analysis, the peak overshoot, settling time and peak time of the system response has found to be less than 40% including the effect of measured disturbance to the plant. Hence, entire process variable optimization has been performed using the parameters of the model predictive controller to provide the proper degree of stability. Finally the proposed method of study has compared with with other control strategies through which the performance the proposed design has been ensured.

An Improved Modelling Approach for the Comprehensive Study of Direct Contact Membrane Distillation

Direct Contact Membrane Distillation (DCMD) is a promising and feasible technology for water desalination. Most of the models used to simulate DCMD are one-dimensional and/or use a linear function of vapour pressure which relies on experimentally determined parameters. In this study, the model of DCMD using Nusselt correlations was improved by coupling the continuity, momentum, and energy equations to better capture the downstream alteration of flow field properties. A logarithmic function of vapour pressure, which is independent from experiments, was used. This allowed us to analyse DCMD with different membrane properties. The results of our developed model were in good agreement with the DCMD experimental results, with less than 7% deviation. System performance metrics, including water flux, temperature, and concentration polarisation coefficient and thermal efficiency, were analysed by varying inlet feed and permeate temperature, inlet velocity, inlet feed concentration, channel length. In addition, twenty-two commercial membranes were analysed to obtain a real vision on the influence of membrane characteristics on system performance metrics. The results showed that the feed temperature had the most significant effect on water flux and thermal efficiency. The increased feed temperature enhanced the water flux and thermal efficiency; however, it caused more concentration and temperature polarisation. On the other hand, the increased inlet velocity was found to provide increased water flux and reduced temperature and concertation polarisation as well. It was also found that the membrane properties, especially thickness and porosity, can affect the DCMD performance significantly. A two-fold increase of feed temperature increased the water flux and thermal efficiency, 10-fold and 27%, respectively; however, it caused an increase in temperature and concertation polarisation, at 48% and 34%, respectively. By increasing Reynolds number from 80 to 1600, the water flux, CPC, and TPC enhanced by 2.3-fold, 2%, and 21%, respectively. The increased feed concentration from 0 to 250 [g/L] caused a 26% reduction in water flux. To capture the downstream alteration of flow properties, it was shown that the ratio of inlet value to outlet value of system performance metrics decreased significantly throughout the module. Therefore, improvement over the conventional model is undeniable, as the new model can assist in achieving optimal operation conditions.

Kinetic modeling and experimental investigations of dry reforming of methanol over a Cr-Mo-Mn/SiO2 catalyst

To derive a kinetic model for dry reforming of methanol, the experimental investigations were accomplished at vast working conditions (i.e., temperature: 500 °C–900 °C and CO2/CH3OH ratio (C/M) of 1–2.5) on Cr-Mo-Mn/SiO2 catalyst. The kinetic model developed based on the Langmuir–Hinshelwood (LH) approach and mechanism contained three reversible reactions on three types of active sites. The results of the statistical analysis presented that kinetic model parameters were statistically significant. The error of the suggested kinetic model was 9.87% using equation state (EoS) of Soave–Redlich–Kwong on the basis of modified Huron–Vidal mixing rule (SRK/MHV2) applied to evaluate vapor–liquid equilibrium behavior. The highest precision in predicting the experimental data by the suggested kinetic model was assigned to methanol conversion. The outcomes presented the high temperature is suitable for higher CO yield, methanol and CO2 conversions. An augmentation in carbon dioxide percentage of the inlet feed led to enhance in CO yield, methanol and CO2 conversions, while H2 yield was decreased.

Energetic Valorization of Cereal and Exhausted Coffee Wastes Through Anaerobic Co-digestion With Pig Slurry

In the past years, there has been steady growth in work relating to improve resource efficiency through waste minimization and bioenergy recovery to mitigate climate change. Agro-food industries produce large amounts of bio-waste, challenging innovative energetic valorization strategies in the framework of circular economy principles. Anaerobic digestion (AD) technology is an interesting route to stabilize organic matter and produce biogas as a renewable energy source. This study involves continuous co-digestion of pig slurry (PS), cereal and exhausted coffee wastes (CECW) performed in a continuously stirred tank reactor, with a hydraulic retention time (HRT) of 16 days under at mesophilic conditions (36.9 ± 0.3°C). The experimental trials, were designed to include different cereal and exhausted coffee liquor (CECL) shares in the feeding mixture, corresponding to different PS to CECL ratios (PS:CECL), respectively: 100:0 (T0), 90:10 (T1), 80:20 (T2), and 70:30 (T3), in terms of percentage of inlet feeding rate (v:v). The results obtained for the feeding rate (70:30) yield to the highest specific methane production (SMP = 341 ml.gVS−1) led to a 3.5-fold improvement in comparison with the reference scenario. The synergetic effect between the microbial consortia of PS and the high carbon to nitrogen ratio (C/N) of CECL explain the improvements achieved. The maximum soluble chemical oxygen demand (SCOD) reduction (84.0%) due to the high content and soluble chemical oxygen demand to total chemical oxygen demand ratio (SCOD/TCOD) corroborate the results achieved. The digester stability, evaluated by specific energetic loading rate, was below the limit (0.4 d−1). Results from ANOVA showed a significant effect of CECL on the resulting GPR and SMP values. Additionally, Tukey's “Honest Significant Difference” method, confirmed statistically significant differences between the trials T3-T0, T3-T1, T3-T2, and T2-T0. Thus, co-digestion of PS and of CECL seems to be a promising approach for bioenergy recovery and promoting biowastes circularity.

Batch and Continuous Chromate and Zinc Sorption from Electroplating Effluents Using Biogenic Iron Precipitates

Nanoparticles of iron precipitates produced by a microbial consortium are a suitable adsorbent for metal removal from electroplating industry wastewaters. Biogenic iron precipitates were utilized as adsorbents for chromate and zinc in batch conditions. Furthermore, the iron precipitates were embedded in alginate beads for metal removal in fixed-bed columns, and their performance was evaluated in a continuous system by varying different operational parameters such as flow rate, bed height, and feeding system (down- and up-flows). The influence of different adsorption variables in the saturation time, the amount of adsorbed potentially toxic metals, and the column performance was investigated, and the shape of the breakthrough curves was analyzed. The optimal column performance was achieved by increasing bed height and by decreasing feed flow rate and inlet metal concentration. The up-flow system significantly improved the metal uptake, avoiding the preferential flow channels.

Modeling and optimization of small-scale NF/RO seawater desalination using the artificial neural network (ANN)

The performance of seawater hybrid NF/RO desalination plant including permeate conductivity; permeate flow rate and permeate recovery. Under different feed parameters time, inlet temperature, inlet pressure, inlet conductivity and inlet flow rate were modelled by Artificial Neural Network (ANN) back-propagation based on Levenberg– Marquardt training algorithm. The optimal ANN model had a 5-8-3 architecture with a hyperbolic tangent transfer function in hidden layer and linear transfer function at the output layer. The ability of ANN performed model was compared with multiple linear regression (MLR). The results show that MLR is not satisfactory for predicting the performance of NF/RO hybrid desalination process with a correlation coefficient about 0.6. The trained ANN model has presented a good agreement between the prediction and the experimental data during the training with reasonable statistical metrics values (RMSE, MAE and AARD). The coefficient of determination values for the prediction of permeate conductivity, permeate flow rate and recovery by ANN were 0.969, 0.942, and 0.963, respectively. Therefore, the ANN model can successfully predict the performance of NF/RO hybrid seawater desalination plant.

Part load operation of natural gas fired power plant with CO2 capture system for selective exhaust gas recirculation

• Model of gas power plant with CO 2 capture for selective gas recycle is presented. • Gas recycle offers stable combustion, higher CO 2 content, low gas flow and reboiler duty. • Part-load operation of gas plant at 80, 60, 40% is analyzed for the parallel and hybrid case. This work investigates base and part load operation of natural gas combined cycle power plant integrated with post-combustion CO 2 capture plant and selective exhaust gas recirculation scheme. Decarbonizing of natural gas combined cycle power plant is complex due to the higher flue gas flow rate with the least CO 2 content ~ 3–4 vol% with residual 20% O 2 and 77% N 2 content. Therefore, the effect of series, parallel and hybrid selective exhaust gas recirculation is examined, a concept where selectively CO 2 can be recycled back and mixed into the ambient air to the inlet feed of the compressor thereby reducing the flue gas flow rate and enhancing CO 2 content at the inlet of capture plant. The study is novel in a way that part-load performance at 80, 60 and 40% for parallel and hybrid scheme of selective exhaust gas recirculation is analyzed through process simulation in Aspen Plus for 606 MW commercial-scale natural gas combined cycle power plant coupled with an amine-based CO 2 capture plant. It is found that the simulation results of power plant and CO 2 capture plant model agrees well with the experimental results. Further, the performance results show the viability of base and part load operation of natural gas combined cycle power plant integrated with CO 2 capture plant by enhancing the CO 2 concentration for hybrid configuration to approximately 19 vol%. For parallel configuration, CO 2 content increases to around 13–14 vol% at 70% recirculation ratio in comparison to 6.6 vol% for simple EGR at 35% ratio. It is found that the selective exhaust gas recirculation offers more stable combustion by maintaining O 2 content at 19 vol% at combustor inlets for parallel and hybrid cases and the flue gas flow rate reduces to 68 and 70%, respectively thus reducing the size of the capture plant. The specific reboiler duty for hybrid, parallel, and series configuration reduces to 3.19, 3.25, and 3.31 MJ/kg CO 2 , respectively in comparison to 3.54 MJ/kg CO 2 for base case natural gas combined cycle power plant coupled with MEA-based CO 2 capture unit. Whereas for 80 to 40% load change, the specific reboiler duty drops from 1.78% to 1.14% for parallel and hybrid configurations, respectively. In conclusion, hybrid selective exhaust gas recirculation configuration shows less efficiency penalty from base load to 40% part load and results in a decrease in specific reboiler duty in comparison to parallel configuration. Therefore, the study is innovative in an aspect that part-load performance at 80, 60 and 40% is performed, and results show a similar pattern as of baseload operation.

Flat sheet direct contact membrane distillation desalination system using temperature-dependent correlations: thermal efficiency via a multi-parameter sensitivity analysis based on Monte Carlo method

In this paper, a 1D model of direct contact membrane distillation is presented in which all fluid properties are temperature-dependent. In addition, a Nusselt number (Nu) relationship for developing flow in ducts (accounting for both thermal and hydrodynamic effects) is used to obtain the convective heat transfer coefficient at each side of the membrane. Simulated mass flux shows very good agreement with experimental measurements at various feed temperature, flow rate and concentration. A comprehensive sensitivity analysis of all operational and geometrical parameters, as well as Nu estimation parameters on water mass flux across the membrane $$(J_{\text{m}} )$$ and thermal efficiency, is also done. To determine the relative importance of each parameter, a multi-parameter sensitivity analysis (MPSA) based on the Monte Carlo method is applied, and the sensitivity index of each parameter at the defined range is computed. Results show that $$J_{\text{m}}$$ is highly sensitive to bulk feed inlet temperature ( $$T_{{{\text{in}},{\text{f}}}}$$ ) while both $$J_{\text{m}}$$ and thermal efficiency are highly sensitive to membrane porosity. Results show that among all parameters, just membrane porosity is highly sensitive which affects both mass flux and thermal efficiency especially at low $$T_{{{\text{in}}.{\text{f}}}}$$ .

Thermal analysis of a hybrid high concentrator photovoltaic/membrane distillation system for isolated coastal regions

The present study introduces an innovative method for fresh water and electricity generation in the isolated regions. This proposed system couples a concentrated photovoltaic (CPV) unit with a membrane distillation (MD) unit. The CPV unit converts solar energy into electrical energy with conversion efficiency of about 40%. The rest is converted to thermal energy, which may cause cells degradation if temperature exceeds manufacturer limits. An intermediate fluid is used as a coolant which transfers the excess energy to the feed of the MD unit through a heat exchanger. The generated thermal energy in the HCPV cells is used as the driving force for the distillation phenomena in the MD unit. Numerical models were built to simulate the hybrid system. It was found that, at a solar radiation concentration ratio of 1000 suns, the coolant flow rate should exceed 150 g/min for a maximum cell temperature less than 349 K. This arrangement should produce 177 W electric power, and 308 W thermal heat transferred to the coolant. At these conditions, the feed inlet temperature reaches about 323 K, at which, the MD unit produces about 5.88 kg/m2.h of pure water, thus allowing the system to simultaneously produce electricity and pure water for isolated coastal regions.

Simultaneous production of hydrogen and acrylonitrile in a new bifunctional micro-reactor, mathematical modeling and optimization study

In the last decade, there have been numerous investigations toward enhancing the efficiency of hydrogen production methods, as well as improving their operational variables. In this work, hydrogen and acrylonitrile are produced in a bench-scale concept by steam reforming of glycerol and ammoxidation of propane, respectively. Based on the present micro-reactor configuration, the needed heat, which is vital for the advancement of the endothermic glycerol steam reforming process in the outer tube, is supplied with the produced heat in the propane ammoxidation reactions in the inner tube. Consequently, in spite of the conventional steam reforming and ammoxidation process, the cooler and furnace are not required. As a result, appropriate energy-saving has been made, along with the reduction of the emission of hazardous greenhouse gases. Adequate improvement can be noticed in the performance of the reactor in which the glycerol conversion has improved from 53.32% to 87.11%. Also, to investigate the impact of the operating condition on the behavior of the proposed reactor configuration, a sensitivity analysis in the case of inlet flow rate, inlet feed composition, and inlet temperature is implemented. It is worth highlighting that the optimization scheme is applied in order for governing the best solution for the suggested configuration within the defined ranges. Optimization outputs established 3.97%, 1.41%, 4.93%, and 3.01% augmentation in the glycerol conversion, hydrogen yield, propane conversion, and acrylonitrile yield, respectively.