Total Specific Energy Consumption Research Articles

Efficient phosphorus removal from ultra-low concentration wastewater by flow-electrode capacitive deionization

During the 14th Five-Year period, the stringent phosphorus emission standard puts forward higher requirements for the phosphorus removal. In this study, lotus leaf-based biochars were prepared by hydrothermal carbonization method and used as low-cost FCDI electrode materials to remove ultra-low concentration phosphorus in wastewater at the first time. The governing factors and optimal adsorption conditions were systematically investigated as 1.2 V applied voltage, 24 s HRT, 10 wt% content of biochars. The maximum removal efficiency reached 98.55 % under 20 mg/L initial phosphorus concentration, which ensured that the phosphorus concentration of the effluent could meet discharge standard (0.3 mg/L) of WWTPs. Furthermore, the microscopic and spectroscopic characterization revealed that phorphorus removal mechanism included physical adsorption, electrosorption, ion exchange, precipitation and ligand exchange, which may take place simultaneously or supplementing each other. Using in situ potential measurement method, the potential gradient and energy consumption contribution of each FCDI component were described. The results showed that total specific energy consumption was very low and the flow electrodes modules dominated (more than 50 %) in all FCDI components. The findings opened up a promising way for managing biowastes and confimed the application of engineering biochar in environmental pollution treatment field.

The Influence of the Long-Term Outdoor Storage of Rockrose (Cistus laurifolius L.) Shrub Biomass on Biofuel's Quality, Pre-Treatment and Combustion Processes.

Biomass storage is an essential requirement in the supply chain of bio-refineries and power plants. This research aims to evaluate the influence of long-term outdoor storage (1 year) of baled rockrose (Cistus laurifolius L.) shrub biomass on biofuel's quality, pre-treatment processes and on combustion emissions in an industrial boiler. The raw material was obtained from different rockrose shrublands in north central Spain. A total of 233 tWM (tones of wet matter) of biomass were used to produce biofuels (30 mm of milled biomass and Ø 8 mm pellets) in the pre-treatment pilot plants at CEDER-CIEMAT. The combustion tests were conducted in an industrial moving grate boiler with a thermal power of 50 MWth, in a 17 MWe power plant. Outdoor storage improved some biofuel quality parameters, mainly the reduction in ash content, which allowed 30 mm of milled material to be classified as class I1 (ISO 17225-9:2022) and pellets as class I3 (ISO 17225-2-2021). No significant differences were observed in the total specific mass flow and energy consumption in the pre-treatment processes. The combustion tests had similar results, with the emissions being below the limits established in the directive (EU) 2015/2193. The results obtained indicated that the 1-year outdoor storage of rockrose-baled biomass, under Mediterranean conditions, was feasible for its subsequent use as biofuel.

ИССЛЕДОВАНИЕ УСТАНОВКИ С ИНФРАКРАСНЫМ НАГРЕВОМ ЗЕРНА

Thermal post-harvest processing of grain currently intended to improve its quality is highly energy-intensive and expensive. The development of new means of mechanization with infrared heating of grain, capable of reducing specific energy costs for heat treatment processes, as well as ensuring resource conservation, is a pressing and important scientific and technical problem. To reduce the cost of drying, disinfection and micronization of grain, as well as improve the quality of its heat treatment, we have developed an experimental model of an installation with infrared heating. The study of the developed installation was carried out in grain drying mode. The technological process of drying wheat grain with an initial moisture content of 18...19% was chosen as the object of study. The total specific energy consumption for grain drying was taken as an optimization parameter. The rational values of the selected factors were determined as a result of a study of the developed installation with infrared heating of grain: grain drying time t1 = 1000C; the temperature created by the infrared heater inside the installation casing is tin = 650C. Next, a series of experiments was carried out on the developed installation in the above modes. In each experiment, measurements were taken of the heating temperature of the grain, the percentage of reduction in grain moisture content and the throughput of the installation were determined, and the total specific energy consumption was recorded. The heating temperature of the grain was in the range of 37 - 38.5 ºС, while the moisture content of the grain decreased by 2.56%. The developed installation provides the required quality of grain drying, maintaining a throughput of about 800 kg/h and a minimum total specific energy consumption, which amounted to 4342.3 kJ h/kg.

Drying process on kaffir lime leaves using microwave: Evaluation of the drying performance and energy analysis of different microwave powers and sizes of leaves

This study aims to determine the optimal microwave power and leaf size by evaluating the drying kinetics model, considering visual appearance, and determining energy consumption (EPW) and specific energy consumption (SEC). The sample will be dried in a batch of 10 g with varied microwave power used for drying (136, 264, 440, 616 W) and three categories of the average size of the sample. Seven thin layer drying kinetics models: Lewis, Page, Logarithmic, Henderson–Pabis, Approximal of diffusion, Verma, and Midilli–Kucuk will be compared for best fitness to experimental data by evaluating five statistical and error functions: SSE, R2, RMSE, χ2, and MSE. Midilli–Kucuk model best fit experimental data with calculation constant a from 0.9656 to 1.0502, b from 2.7403×10−5 to 0.0006, k from 0.0008 to 0.0222, and n from 0.8188 to 1.5755. The total energy and specific energy consumption showed fluctuating values in varying drying times, and microwave power with the most optimum setting is drying the large-sized sample in 264 W.

Exergy and pinch investigation of a novel configuration for the liquid hydrogen production by polymer electrolyte membrane electrolyzer and mixed refrigerant-absorption cooling cycles

The increase in global energy consumption leads to international commitments to replace fossil fuels and reduce environmental consequences. To improve and reduce the imbalance between the production and use of renewable energy, new ways should be considered for the distribution, and transmission, storage of global energy. Liquid hydrogen is a clean fuel that can be used for long-term storage and transportation to distant places. High energy consumption, losses due to boil-off gas, and low exergy efficiency in hydrogen liquefaction units are the main challenges. Waste heat recovery from various industries in the form of refrigeration can be used in hydrogen production and liquefaction. This study proposes an innovative process configuration for the generation of liquid hydrogen. The proposed process consists of a polymer electrolyte membrane electrolyzer, a Kalina power unit, a cascade absorption-compression refrigeration cycle, and three multi-component refrigerant cascade processes. The simulation of the proposed structure is performed in ASPEN HYSYS and m-file MATLAB. The verification is conducted highly accurately based on reference data. The proposed hybrid configuration produces 2066 kmol/h liquid hydrogen, 1033 kmol/h oxygen, and 14,572 kmol/h hot water using a power consumption of 272.2 MW. The proposed system's energy, exergy, pinch, and sensitivity are analyzed to give a better insight into its capabilities. Results show the total specific energy consumption of the present study is lower than similar studies in this field. In addition, the cooling capacity per unit flue gas mass flow rate obtained in the present study is 4.70 % and 7.69 % higher than similar studies, respectively. Also, the exergy efficiency of the proposed structure is 23.58 %, demonstrating an increase compared to the reference data. The exergy analysis indicated the highest exergy destruction was related to the PEM electrolyzer, followed by heat exchangers and reactors. Minimum pinch temperatures of the HX2, HX3, and HX4 exchangers based are achieved at 1.000, 1.006, and 1.020 K, respectively. The performed sensitivity analysis indicates that by increasing the temperature of flue gas from 600 to 1000 K, the specific power consumption of the liquid hydrogen production process decreases from 7.354 to 7.208 kWh/kgLH2.

A novel integrated hydrogen and natural gas liquefaction process utilizing a modified double mixed refrigerant process pre-cooling system

The hydrogen liquefaction process is energy-intensive due to the lower liquefaction temperature. To improve the energy efficiency of the hydrogen liquefaction process, a novel integrated liquefaction process employing a modified double mixed refrigerant process pre-cooling is proposed and analyzed. The three-stage adiabatic ortho–para hydrogen conversion makes the process compact. Furthermore, the particle swarm optimization algorithm is utilized to find the optimal decision variables. The result reveals that the total specific energy consumption (SEC) of the process is 6.5921 kWh/kgLH2-LNG, which is 15.83% lower than the base case. The SECs for the production of LNG and LH2 are 0.2445 kWh/kgLNG and 6.3476 kWh/kgLH2. Moreover, the exergy analysis and thermodynamic evaluation reveal that the exergy efficiency, coefficient of performance, and figure of merit of the process are 49.26%, 0.2306, and 0.49, exhibiting high thermodynamic performance. Finally, the sensitivity analysis indicates that the evaporation pressure of the sub-cooling refrigerant has the greatest impact on the performance of the process. The proposed process has an important reference value in the design of the combined production of LH2 and LNG from industrial by-products and the H2 liquefaction process.

Elevation-distributed multistage reverse osmosis desalination with seawater pumped storage

A seawater reverse osmosis (RO) plant layout based on multistage RO with stages located at different elevations above sea level is described. The plant uses the weight of a seawater column from pumped storage as head pressure for RO (gravity-driven multistage RO) or to supplement high-pressure pumps used in RO (gravity-assisted multistage RO). The use of gravitational force reduces the specific energy for RO compared to using high-pressure pumps. By locating the RO stages at different elevations based on demand sites, the total specific energy consumption for RO and permeate transport to different elevations above sea level is reduced from that for locating the RO process entirely at sea level followed by lifting the desalinated water. A final RO stage at sea level uses seawater pressurized by energy recovery from the residual energy of the brine generated from the preceding RO stage. Examples of the plant layout that do not include pump inefficiency and head losses in pipes are described for South Sinai, Egypt, which is a mountainous region that suffers from water scarcity. A gravity-driven multistage RO with a storage tank at 660 m above sea level is considered. For five RO stages located 316–57 m above sea level with 10% recovery at each stage, the specific energy is ~ 32% lower than that for a plant located at sea level operating at the minimum specific energy followed by lifting the same quantity of desalinated water to the elevations of the distributed RO stages. For two stages located at 222 and 57 m above sea level with 30 and 20% recovery, respectively, the reduction in specific energy is ~ 27%. For gravity-assisted five-stage RO with the first stage at 260 m above sea level, while the last stage is at sea level with 10% recovery at each stage the reduction in specific energy is ~ 32%. The proposed RO plant layouts can be adapted to other regions with comparable topography.

Performance Evaluation of Liquorice Harvester with Novel Oscillating Shovel-Rod Components Using the Discrete Element Method

Liquorice harvesting is the key process in the development of the liquorice industry. For harvesting liquorice with about 400 mm growth depth, a lightweight harvester with novel oscillating shovel-rod components was developed. Draft force, total torque, specific energy consumption, separation proportion, and soil structure maintenance were used to evaluate harvester performance under varied working conditions, and throw intensity and total torque were analyzed. A DEM model was developed to simulate the excavation and separation of soil. Three sets of single-factor simulation tests and one set of field tests were conducted. The results indicated that: Each 1 mm increase in amplitude decreased draft force by 463.35 N and increased total torque and specific energy consumption by 35.03 Nm and 4.3 kJ/m3, respectively. Each 1 Hz increase in vibration frequency increased specific energy consumption by 3.12 kJ/m3, while draft force and total torque decreased by 375.75 N and 28.44 Nm, respectively. Each 0.1 m/s increase in forwarding speed increased the draft force, total torque and specific energy consumption by 1302.72 N, 13.26 Nm and 3.82 kJ/m3, respectively. The main separation areas of the shovel-rod were front areas, where the soil separation proportion is greater than 60%, and the soil was completely separated at the end areas. The soils after harvesting had a relatively minimal disturbance in all layers, with soil structure maintenance greater than 0.61, and soil structure was well maintained. The liquorice plants were separated from the soil after passing smoothly through the oscillating shovel-rod components, during which the soil at different layers fell in sequence. This study revealed the interactive relationship between working components and soil, specifically the potential to maintain soil structure after harvesting. This new finding will assist in developing harvest techniques for rhizome crops with deep growth depth.

Multi-objective optimization of a small-scale solar-hot-spring-geothermal brackish water direct contact membrane distillation system

A small-scale solar-hot-spring-geothermal brackish water membrane distillation (MD) system is proposed by combining hot-spring and solar components to reduce fossil energy consumptions. A performance parameter framework and carbon footprint model is developed to perform an analysis on whole life cycle of the proposed system. The results show that the solar subsystem improved heat recovery with the water generation ratio increased by 22–42 %. As the feed-side inlet temperature increases, the total Specific Energy Consumption (SEC) contribution rate of renewable geothermal and solar energies increases from 12.34 % to 20.45 %. The cold and hot sources are responsible for the largest exergic losses at 1.79 kJ/S and 0.48 kJ/S. The unit exergy cost of the solar subsystem is the highest of 0.037 $/h in terms of economic benefits. One of effective ways to improve the carbon emission reduction rate is to develop a cogeneration process for the water purification. A multi-software co-simulation methodology is proposed to explore innovative MD systems of optimal configurations, improve desalination efficiency and reduce the energy consumptions. The Non-dominated Sorting Genetic Algorithm (NSGAII) and improved NSGAII genetic algorithms (NSGAII-A and NSGAII-B) are utilized for multi-objective optimization of the MD system. Finally, the Technique for Order Preference by Similarity to Ideal Situation (TOPSIS) method based on entropy weight is employed to obtain the Pareto frontier solution set. It is indicated that NSGAII-B based on the four objective-optimal scheme is the best for the Multi-objective optimization of the MD system.

Cold filamentary microplasma pretreatment combined with infrared dryer: Effects on drying efficiency and quality attributes of apple slices

Cold filamentary microplasma (CFM) pretreatment combined with infrared (IR)dryer was implemented, and its effect on drying efficiency (i.e., (drying) kinetics and moisture diffusivity) and quality attributes (i.e., total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AOA), ferric reducing antioxidant power (FRAP), color, and FT-IR spectra) of apple slices (5, 7, and 10 mm thicknesses) were examined. Results showed the electrically induced channels in the CFM-pretreated samples appeared as a tree-like structure. Besides the drying time decreases of 18.0%, 13.0%, and 10.5% that respectively occurred at CFM-pretreated IR-dried apple slices thicknesses 5, 7, and 10 mm, the browning therein appeared as the main visual effect with reduced total specific energy consumption. CFM-pretreatment enhanced the dried apple slices’ quality via increasing TPC, TFC, and AOA respectively ranging 2.5–14.3%, 19.1–25.9%, and 8.3–35.4%. Additionally, the detected chemical compounds corroborated the FT-IR spectral peaks. • Cold filamentary microplasma (CFM) pretreatment and infrared (IR) drying were combined. • Drying efficiency and quality attributes of CFM pre-treated IR dried apple slices were investigated. • CFM pre-treated IR drying appear more effective on thin apple tissue thicknesses. • CFM pre-treated IR drying is promising to sustain the apple slice quality.

Low energy resonance vibration submerged membrane system for microalgae harvesting: Performance and feasibility

This study investigated an energy-efficient harvesting method to collect microalgae of Chlorella Vulgaris (C. vulgaris). The method proposed in the current study was a combination of a resonance vibration submerged membrane (RVSM) system and centrifugation. The result showed that the RVSM system was able to concentrate the C. vulgaris solution by 17 times (0.61 g·L−1 to 10.4 g·L−1) without chemical cleaning during filtration with intermittent relaxation (i.e., filtration for 9 min and relaxation for 1 min) at a flux of 40 LMH (L·m−2·h−1) until the transmembrane pressure (TMP) reached 70 kPa. In addition, extracellular polymeric substances such as polysaccharides and protein were found mainly responsible for membrane fouling during the operation of concentrating C. vulgaris solution. Integrating the RVSM system with the centrifugation process required the total specific energy consumption of 0.56 kWh·m−3 (0.09 kWh·m−3 for the RVSM and 0.47 kWh·m−3 for the centrifugation). This study demonstrated the combination of the RVSM system and centrifugation to be a feasible C. vulgaris harvesting method by showing lower energy consumption than other conventional processes.

Modeling and Simulation of Extended-Range Electric Vehicle with Control Strategy to Assess Fuel Consumption and CO2 Emission for the Expected Driving Range

Extended-Range Electric Vehicles (EREVs) are intended to improve the range of battery electric vehicles and thus eliminate drivers’ concerns about running out of energy before reaching the desired destination. This paper gives an insight into EREV’s performance operating according to the proposed control strategy over various driving cycles, including the Worldwide Harmonized Light-duty Test Cycle Class 3b (WLTC 3b), Federal Test Procedure (FTP-75), and China Light-Duty Vehicle Test Cycle (CLTC-P). Simulation runs were performed in Matlab-Simulink® for different cases of drive range, electricity mix, and vehicle mass. The control strategy goal was to aim at a specified value of battery state of charge at the targeted range value. The obtained test results included: pure electric drive range, acceleration times, EREV range tests, control strategy range errors, Range Extender (REX) utilization metric and distribution of its engagement instances, fuel consumption, total equivalent CO2 emission, powertrain efficiency, and specific energy consumption. The control strategy operated on average with a range error of −1.04% and a range mean square error of 2.13%. Fuel consumption (in range extension mode) varied between 1.37 dm3/100 km (FTP-75) and 6.85 dm3/100 km (WLTC 3b Extra-High 3). CO2eq emission was 95.3–244.2 g/km for Poland, 31.0–160.5 g/km for EU-27, and 1.2–147.6 g/km for Sweden. This paper is a valuable source of information for scientists and engineers seeking to learn the advantages and shortcomings of EREV drives with a proposed control strategy, based on various sets of results.

Modernization of operating chicory factories using continuous pulsating extractors

Chicory roots are a valuable source of inulin and other healthy nutrients. The most common direction of their industrial processing is instant chicory powder production. Extraction is the main process in the production. Conventional extraction methods, which include maceration, percolation and extraction in a screw extractor, have a number of significant drawbacks, including high capital and operating costs, low quality of the resulting extract, complexity in repairing equipment, short overhaul life, etc. The purpose of the present study was to assess the technical feasibility of increasing extraction process efficiency through using continuous pulsating extractors (CPE) developed by the Ingehim company, in which a non-stationary, countercurrent mode of interaction of raw materials with the extractant is incorporated. Testing of engineering solutions implemented in CPE was carried out at a pilot pulsating unit (PPU). For extraction, roasted and crushed (5–20 mm) chicory roots from one of the operating chicory factories were used. The ratio chicory : water during extraction was 1 : 4.5, which is 1.5–2.5 times lower than in conventional extractors. A lower extraction temperature (up to 85°C) combined with a shorter extraction time (up to 1 hour) may help retain more inulin and other nutrients as compared to conventional methods. The results of the study at the PPU under these conditions confirmed the high yield of water-soluble solids (up to 98%) without additional grinding. A scheme for the modernization of a chicory factory equipped with the most common percolation extraction equipment having a feed capacity of 400 kg/h is proposed through using CPE. 3D images of the proposed modernization are shown. A comparative assessment of energy consumption for extraction using different methods is given. The results of the study indicate the capability and high efficiency of CPE for extracting chicory, which is confirmed by a decrease of up to 3.6 times in the total specific energy consumption for obtaining 1 kg of instant chicory powder compared to conventional extractors. Low capital and operating costs determine the prospects for using CPE for the modernization of existing chicory factories or the creation of new energy-efficient factories.

Modeling moisture and solids transfer kinetics during a novel microwave assisted water absorption-desorption process of dry red gram (Cajanus cajan L.) splits

The microwave-assisted water absorption and desorption of dry polished red gram splits were done to reduce its anti-nutritional compounds, improve cooking characteristics, save energy and reduce water requirements. The newly developed process was compared with soaking of red gram splits in water at ambient and 60 °C. Peleg model and modified Azuara model were used to study the water absorption and solid loss kinetics while considering the dry matter holding capacity and surface tension of red gram. The process showed 61.40% db moisture gain and 6.30% db solid loss in 7 min. Further, microwave drying at optimum condition (1.25 W/g and 1.5 pulsation ratio) that was determined using response surface methodology resulted in 50 and 10 min of drying and cooking times, respectively. Compared with raw and conventionally treated samples, the microwave process resulted in a product with an improved rehydration ratio and solids dispersion of 3.00 and 31.90%, respectively. The total specific energy consumption in microwave treatment was 93% lesser than the control methods. • Microwave treatment improved the quality and cooking characteristics of red gram splits. • Microwaves accelerated water absorption by reducing the surface tension. • Low solid loss and high dry matter holding capacity was observed after microwave treatment. • The water absorption and solid loss kinetics were best described by Azuara models. • Total energy consumption in microwave processing was 93% lesser than conventional methods.

Extractive distillation of ethyl acetate-ethanol-water ternary system using deep eutectic solvent (DES): A techno economic and energy assessment

The extractive distillation (ED) process has been established as a commercially viable process that can be used to break the azeotropic systems. The present study investigates the performance and feasibility of conventional solvent (glycerol) and choline chloride-glycerol based deep eutectic solvent (DES) as entrainers for the separation of ethyl acetate-ethanol-water ternary mixture through ED. A comprehensive approach is proposed with phase-equilibrium measurements and process simulation through Aspen Plus for different entrainer to feed ratio (E/F). Optimization of the process is based on performance indicators such as Total Annual Cost, CO2 emissions, and Specific Energy Consumption. A sequential iterative algorithm was used to find the optimum E/F in distillation trains. The performance analysis has shown a reduction of 45.89% in global TAC with DES as an entrainer. The combined entrainer requirement for the dehydration was 268.3 kmol/h and 118.86 kmol/h with glycerol and DES respectively. The process sees a 58.21% total energy saving with a 15% and 44.5% reduction in Specific Energy Consumption and CO2 emissions respectively as compared to glycerol as an entrainer. The study provides a comparison and proves that DES is an effective entrainer to break the azeotropic point as a low-cost and eco-friendly alternative to conventional solvents.

Evaluation and selection of machine-tractor units during cultivation by energy costs

The materials on evaluation and selection of machine-tractor units by the criteria of minimization of their production and operation costs (total specific energy intensity of MTU for its production and operation) and maximum productivity in carrying out the technological process of soil cultivation are presented. It has been established that the range of technological machines for carrying out the technological process "cultivation" with the power of mobile power plants up to 110 hp is determined by cultivators such as KPS-4, KBM-4.2 type using tractors JD5620, AGCO MF3640, UMZ-6, LTZ 95B, JD6020, MTZ-80/82, MTZ-920, Belarus 900, Belarus-921, Belarus-923, Deutz Agrofarm 430 and MTZ-1025. They have the total specific energy intensity of use with the designated technological machines at the minimum level, and the productivity at the maximum. In the power range of tractors from 110 to 145 hp it is advisable to use cultivators KSHU-5, KSHU-6, KPS-8P with mobile power tools New Holland T6050 Delta, CASE IH Maxxum 125, JD 6130D, JD 6135, MTZ-1221, Belarus 1220, LTZ-155 and MTZ-1222, which also have the maximum productivity at the minimum level of the total specific energy consumption for their production and operation. It has been found that when using cultivators of the type KSHU-12, KBM-7.2P, KBM-10.8P, Leader-6N, APC-7,2, RTS1831, KPO-7.2, KORUND 8/900 (power of the energy means up to 150-210 hp), according to the indicated efficiency criteria, it is advisable to use tractors T–150K, MTZ-1523, HTZ-121, HTA 200- 10, Belarus 1525, HTZ 17221, Terrion ATM 3180, Deutz Fahr Agrotron 165.7, JD 7030, ATM 4200 Terrion, MTZ-2022. It has been established that for the use of cultivators Leader-7.2N, Leader-8, according to the indicated criteria for minimizing energy consumption and maximum productivity, tractors with a power of up to 210-240 hp like JD 7830, JD 7930, New Holland 7060, Deutz Fahr Agrotron L720 DCR, Claas Axion 850 are required.

A multi-objective optimisation framework for MED-TVC seawater desalination process based on particle swarm optimisation

Owing to the high specific energy consumption associated with thermal desalination technologies such as Multi Effect Distillation (MED), there is a wide interest to develop a cost-effective desalination technology. This study focuses on improving the operational, economic, and environmental perspectives of hybrid MED-TVC (thermal vapour compression) process via optimisation. Application of particle swarm optimisation (PSO) in several engineering disciplines have been noted but its potential has not been exploited fully in desalination technologies especially MED-TVC in the past. A multi-objective non-linear optimisation framework based on PSO is constructed here. Two of our earlier models have been used to predict the key process performance and cost indicators. The models are embedded within the PSO optimisation algorithm to develop a new hybrid optimisation model which minimises the total freshwater production cost, total specific energy consumption and brine flow rate while maintaining a fixed freshwater production for a given number of effects and seawater conditions. The steam flow rate and temperature are considered as control variables of the optimisation problem to achieve the objective function. The PSO has successfully achieved the optimum indexes for the hybrid MED-TVC process for a wide range of number of effects. It also shows a maximum reduction of freshwater production cost by 36.5%, a maximum energy saving by 32.1% and a maximum reduction of brine flow rate by 38.3%, while maintaining the productivity of freshwater.

Renewable energy powered membrane technology: Energy consumption analysis of ultrafiltration backwash configurations

In the field of ultrafiltration (UF) membranes for water treatment, fouling is a severe problem that limits the potential of the technology UF membranes and results in increased energy consumption. In this study, a small-scale photovoltaic-powered membrane system was employed to investigate the energy consumption of two UF backwashing configurations – a bladder tank and a backwash (BW) pump powered by supercapacitors – under varied solar irradiance conditions. Fouling was induced via the addition of bentonite, and then examined at varied BW intervals using the bladder tank to optimize the total specific energy consumption (TSEC) – determined for both UF BW and reverse osmosis (RO) desalination processes. Simulated fouling – realized via a pressure drop across a ball valve – was proposed to induce inorganic fouling without requiring the addition of foulants. The TSEC of both bentonite and simulated fouling was compared. Under simulated fouling and constant solar irradiance operating conditions, the bladder tank exhibits a BW SEC of 0.3 Wh/L, while the BW pump exhibits SEC of 0.09Wh/L. The TSEC is maintained at ∼ 4 Wh/L under varied real “solar days” with the bladder tank, indicating that the energetic penalty for implementing one BW cycle every 90 min is small. A BW interval of 60 min exhibited a TSEC of 3.7 Wh/L and provided a good compromise between TSEC and the mitigation of membrane fouling. The concept of using a valve to simulate fouling in the system can assist with the UF membrane fouling studies without inducing irreversible fouling to the membrane. Despite its higher BW SEC, the bladder tank was a more robust setup and is recommended for adding BW functionality to renewable-energy powered membrane filtration systems.

Effect of Drying Temperature on Drying Characteristics, Total Phenolic Content and Antioxidant Activity of Slightly Sticky Mango (Mangifera Indica L.) Sheet

Dried slightly sticky mango sheets is healthy sweet snack, having slightly chewy texture. The objective of this work was to study the effect of drying temperatures (60, 70 and 80 °C) on the drying characteristics, total phenolic content (TPC), antioxidant activity (assessed by DPPH and ABTS scavenging activity assays) and specific energy consumption of the dried slightly sticky mango sheets. The experimental results showed that the times required to reach the desired final moisture content were 230, 150 and 120 min when drying was performed at the temperatures of 60, 70 and 80 °C, respectively. The total specific energy consumption (SECtotal) values of the drying at 70 and 80 °C were lower than that at 60 °C. However, the TPC and the antioxidant activities assessed by DPPH and ABTS scavenging activity assays were not significantly different amongst the samples dried at different temperatures.

System level heat integration and efficiency analysis of hydrogen production process based on solid oxide electrolysis cells

The solid oxide electrolysis cells (SOEC) technology is a promising solution for hydrogen production with the highest electrolysis efficiency. Compared with its counterparts, operating at high temperature means that SOEC requires both power and heat. To investigate the possibility of coupling external waste heat with the SOEC system, and the temperature & quantity requirement for the external waste heat, a universal SOEC system operating at atmospheric pressure is proposed, modeled and analyzed, without specific waste heat source assumption such as solar, geothermal or industrial waste heat. The SOEC system flow sheet is designed to create opportunity for external waste heat coupling. The results show that external waste heat is required for feed stock heating, while the recommended coupling location is the water evaporator. The temperature of the external waste heat should be above 130 °C. For an SOEC system with 1 MW electrolysis power input, the required external waste heat is about 200 kW. When the stack operates at thermoneutral state and 800 °C, the specific energy consumption is 3.77 kWh/Nm3-H2, of which electric power accounts for 84% (3.16 kWh/Nm3-H2) and external waste heat accounts for 16% (0.61 kWh/Nm3-H2). The total specific energy consumption remains almost unchanged when operating the SOEC stack around the thermoneutral condition.