Energy Efficiency Of Process Research Articles

Thermodynamic Analysis and Optimization of Power Cycles for Waste Heat Recovery

Improvement of energy efficiency in technological processes at industrial enterprises is one of the key areas of energy saving. Reduction of energy costs required for the production of energy-intensive products can be achieved through the utilization of waste heat produced by high-temperature thermal furnace units. Generation of electric power based on the waste heat using power cycles with working fluids that are not conventional for large power engineering, may become a promising energy saving trend. In this paper, thermodynamic analysis and optimization of power cycles for the purposes of waste heat recovery are performed. The efficiency of combining several power cycles was also evaluated. It has been established that the combination of the Brayton recompression cycle on supercritical carbon dioxide with the organic Rankine cycle using R124 allows for greater electrical power than steam-power cycles with three pressure circuits under conditions where the gas temperature is in the range of 300–550 °C and the cooling temperature of is up to 80 °C. Additionally, when cooling gases with a high sulfur and moisture content to 150 °C, the combined cycle has greater electrical power at gas temperatures of 330 °C and above. At enterprises where the coolant has a high content of sulfur compounds or moisture and deep cooling of gases will lead to condensation, for example, at petrochemical and non-ferrous metallurgy enterprises, the use of combined cycles can ensure a utilization efficiency of up to 45%.

Recent Strategies of Oxygen Carrier Design in Chemical Looping Processes for Inherent CO2 Capture and Utilization

AbstractChemical looping processes are considered a promising pathway for the efficient production of various fuels and chemicals. Temporally or spatially separated reduction and oxidation reaction in chemical looping can offer various advantages such as enhancing energy efficiency, surpassing equilibrium limitations, and eliminating the need for separation. However, the efficiency of the chemical looping process highly depends on the performance of the oxygen carrier. Higher gas conversion can increase separation efficiency and higher solid conversion can reduce the amount of cycled oxygen carrier. The performance indicators are highly related to the thermodynamic properties of the oxygen carriers and their redox kinetics. This review introduces some key articles and recent achievements for the enhancement of such properties. The different research strategies are discussed for enhancing the performance of stoichiometric and non-stoichiometric oxygen carriers. Through the rational design of oxygen carrier material, an energy-efficient chemical looping process is possible.

Training all-mechanical neural networks for task learning through in situ backpropagation

Recent advances unveiled physical neural networks as promising machine learning platforms, offering faster and more energy-efficient information processing. Compared with extensively-studied optical neural networks, the development of mechanical neural networks remains nascent and faces significant challenges, including heavy computational demands and learning with approximate gradients. Here, we introduce the mechanical analogue of in situ backpropagation to enable highly efficient training of mechanical neural networks. We theoretically prove that the exact gradient can be obtained locally, enabling learning through the immediate vicinity, and we experimentally demonstrate this backpropagation to obtain gradient with high precision. With the gradient information, we showcase the successful training of networks in simulations for behavior learning and machine learning tasks, achieving high accuracy in experiments of regression and classification. Furthermore, we present the retrainability of networks involving task-switching and damage, demonstrating the resilience. Our findings, which integrate the theory for training mechanical neural networks and experimental and numerical validations, pave the way for mechanical machine learning hardware and autonomous self-learning material systems.

Improve the energy efficiency of the fruit freeze-drying through the predictive analysis

The considerable energy expenditure involved in the freeze-drying of foods justifies the development of innovative engineering techniques. Artificial intelligence will facilitate mass balance and energy efficiency in future food freeze-drying processes. This study assessed the energy and manufacturing efficiency of the freeze-drying facility through the application of artificial intelligence. Two distinct artificial neural network models were created utilizing real-time data from a factory located in an industrial zone that processed freeze-dried vegetables and kiwi fruit. Analyzing energy efficiency values and production was done using network models constructed from 20 experimental data sets. The Levenberg-Marquardt approach was employed to train neural networks with a multilayer perceptron architecture. The neural network models' prediction values were compared with the experimentally acquired data, and their performance was examined using several performance criteria. The evaluations carried out for 20 different scenarios revealed overall energy efficiency rates ranging from 25.8% to 64.5%. The considerable energy expenditure involved in the freeze-drying of foods justifies the development of innovative engineering techniques. Artificial intelligence will facilitate mass balance and energy efficiency in future food freeze-drying processes.

Increase in the energy efficiency of the biogas production process through vibration activation of heat and mass exchange processes in the bioreactor

Increase in the energy efficiency of the biogas production process through vibration activation of heat and mass exchange processes in the bioreactor

An energy-efficient near-data processing accelerator for DNNs to optimize memory accesses

An energy-efficient near-data processing accelerator for DNNs to optimize memory accesses

Low-temperature rapid fabrication of crosslinked poly(quaterphenyl piperidine) membrane for anion exchange membrane water electrolyzers

While nonsolvent-induced phase separation (NIPS) is widely recognized as an established method for creating porous polymer membranes, this study uniquely employs a nonsolvent to produce a dense, nonporous membrane instead. Specifically, the membranes were rapidly fabricated at low temperatures using dimethyl sulfoxide (DMSO), a high-boiling-point solvent, and water as the nonsolvent. We successfully prepared a series of crosslinked poly(quaterphenyl piperidine) (PQP-BM) network membranes with high crosslinking degrees (up to 47.2 %). By combining a hydrophobic extended polyaromatic backbone with a hydrophilic piperidine-based crosslinker, we achieved distinct microphase separation, which enhanced ion transport, dimensional stability, and thermal and mechanical properties compared to the linear uncrosslinked membranes. The optimized AEM exhibited exceptional mechanical strength (tensile strength >63 MPa), high ion conductivity (151.5 mS cm⁻¹ at 80 °C), and excellent alkaline durability. In single-cell water electrolyzer tests, the PQP-BM membrane demonstrated a remarkable current density of 3.99 A cm⁻² at 2.0 V in 1 M KOH at 50 °C, outperforming the commercial FAA-3–50 membrane by 126 %. This study highlights the potential of the energy-efficient NIFF process as a scalable method for producing advanced AEMs for energy conversion applications.

Thermodynamic Analysis of the Concentration Process of Solar Radiation

Extremely rarefied but high-temperature solar radiation energy is nowadays commonly concentrated to produce a high-temperature heat source. The article is a contribution to theoretical considerations on the process of concentration of solar radiation. The process of concentration of extraterrestrial solar radiation was subjected to thermodynamic analysis and the energetic, entropic and exergetic points of view were taken into account. An imaginary model of concentration was defined, which allowed the development of thermodynamic analyses of the concentration process. In the model, concentrated solar radiation irradiates the absorbing surface, the temperature of which is controlled by the intensity of cooling. The newly revealed values of temperature (7134 K) of the Sun's surface and its energetic and exergetic emissivity (0.431 and 0426, respectively) were used in the analyses. With the use of model equations, the relationship between the ratio of radiation concentration, temperature and emissivity of the absorption surface, cooling intensity, absorbed heat, ambient temperature, and energy and exergetic efficiency of the concentration process was determined. Entropy analysis confirmed that the concentration limit temperature is equal to the temperature of the Sun's surface. Examples of energy and exergetic balances of the concentration process, illustrated by band diagrams, showed the percentage share of energy and exergy fluxes. In contrast to the energy balance showing no energy loss, the exergy balance showed a significantly large loss of exergy due to the irreversibility of the process. The components of this irreversibility have been identified, which are the absorption of solar radiation and the much lower irreversibility of the emission of the heated surface.

FACTORS INFLUENCING THE FORECAST OF ENERGY CONSUMPTION OF THE COUNTRY IN THE CONDITIONS OF WAR AND THE AMOUNT OF REDUCTION OF GREENHOUSE GAS EMISSIONS

The article highlights three main factors that influence the forecast of the consumption of energy in the economy of Ukraine. These are structural shifts in its economy, changes in the structure of energy consumption in Ukraine, and volumes and directions of reduction of greenhouse gas emissions (GHG) in the conditions of compliance with international emission limitations. The conservative scenario of the development of the country's economy is considered. It predicts a moderate recovery, with the economy growing at 2.5 % per year. This pace has been chosen under the condition of the continuation of russia's armed aggression against Ukraine and the end of the active phase of hostilities by the end of 2025. The change in the structure of the economy during russia's military aggression against Ukraine was studied. The directions of further development of key sections of the economy have been determined. Strategic measures to reduce GHG emissions are highlighted, primarily in industry and in the energy sector in particular. Reducing fuel consumption by types of industrial sectors in Ukraine will be achieved through the introduction of energy-efficient technologies and processes aimed at reducing energy consumption in production, by switching to the use of more ecological energy sources, such as renewable energy sources; modernization of industrial facilities and equipment to reduce fuel consumption; implementation of energy saving and energy efficiency promotion programs in industry; reforming the energy sector and increasing energy efficiency in general. According to the updated nationally defined contribution of Ukraine to the Paris Agreement in 2021, the country committed to achieving a reduction of greenhouse gas emissions by 35 % from the 1990 level by 2030 and switching to energy-efficient and low-carbon technologies. Keywords: structure of the economy, energy resources, structure of energy consumption, forecasting, greenhouse gases.

Calcium ion-triggered liquid-liquid phase separation of silk fibroin and spinning through acidification and shear stress

Many studies try to comprehend and replicate the natural silk spinning process due to its energy-efficient and eco-friendly process. In contrast to spider silk, the mechanisms of how silkworm silk fibroin (SF) undergoes liquid–liquid phase separation (LLPS) concerning the various environmental factors in the silk glands or how the SF coacervates transform into fibers remain unexplored. Here, we show that calcium ions, among the most abundant metal ions inside the silk glands, induce LLPS of SF under macromolecular crowded conditions by increasing both hydrophobic and electrostatic interactions between SF. Furthermore, SF coacervates assemble and further develop into fibrils under acidification and shear force. Finally, we prepare SF fiber using a pultrusion-based dry spinning, mirroring the natural silk spinning system. Unlike previous artificial spinning methods requiring concentrated solutions or harsh solvents, our process uses a less concentrated aqueous SF solution and minimal shear force, offering a biomimetic approach to fiber production.

Thermoeconomic Evaluation of the Triple Pressure-Swing Distillation Process

Objective: Investigate distillation as a separation process based on the difference in volatility of components, focusing on the separation of azeotropic mixtures using Pressure-Swing Distillation (PSD). The study was applied to the ternary mixture water-acetonitrile-isopropanol (Water-ACN-IPA). Theoretical Framework: Based on previous studies that demonstrated the feasibility of PSD for separating this mixture using three columns operating at different pressures. However, challenges related to high energy consumption persist due to system irreversibilities. Method: Hydraulic analysis of the columns is proposed, including the implementation of variable diameter and thermal integration as optimization strategies. Results and Discussion: Results show a 47.5% reduction in the total annual cost (TAC), demonstrating greater economic efficiency and process viability. Research Implications: The study contributes to improving energy efficiency in azeotropic separation processes using PSD, providing practical solutions to minimize costs and environmental impacts. Originality/Value: This work introduces technical innovations in azeotropic distillation using PSD, offering an economically optimized and viable approach for the chemical, petrochemical, and pharmaceutical industries.

Pulsed Electric Field Treatment in Extracting Proteins from Legumes: A Review

A healthy diet rich in plant proteins can help in preventing chronic degenerative diseases. Plant-based protein consists of derivatives from algae, fungi (like mushrooms) and other plant products including stems, leaves, fruits, vegetables, grains, seeds, legumes and nuts. These sources are not only rich in protein, but also contain a high percentage of iron, calcium, folates, fiber, carbohydrates, fats etc. Hence, it is essential to explore plant-based protein sources and their other nutritional components to address existing food insecurity issues. Nowadays, the impact of food processing has produced promising results in extracting valuable bio-compounds including proteins from the plant matrix. In this view, PEF technology has secured an exceptional place in solving food quality issues through minimized thermal effects in the samples, improved extraction capabilities at a shorter time, higher extraction levels, high nutritional content of extracted samples, greater shelf-life extension and increased microbial killing efficiency. It is an energy efficient process which is used as a pre-treatment to increase selective extraction of intracellular compounds through electroporation technique. Here, the processing parameters play a significant role in obtaining enhanced extraction levels. These parameters have also considerably influenced the protein digestibility and amino acid modification. So far, PEF has been producing remarkable results in plant protein extraction research. Among various plant sources mentioned above, there is a limited literature available on the use of PEF-assisted protein extraction from legumes. In this review, the authors have discussed essential legumes and their nutritional components and have highlighted how PEF can be beneficial in extracting the protein levels from these sources. Further research should focus on PEF-assisted protein extraction from legumes, specifically analyzing the properties of protein quality and quantity.

A Diagnostic Approach to Improving the Energy Efficiency of Production Processes—2E-DAmIcS Methodology

This article presents the issue of energy waste in manufacturing processes, focusing on reducing unnecessary energy consumption and CO2 emissions. A significant challenge in modern production is identifying and minimizing energy waste, which not only increases operational costs but also contributes to environmental degradation. An improvement methodology referred to as 2E-DAmIcS is proposed. A distinguishing feature of the methodology is a risk map of energy waste in the production process. Application of the methodology is demonstrated using the example of a lead–acid battery production process. It is shown that even small but well-diagnosed changes to the process make it possible to significantly reduce energy consumption. The proposed methodology offers practical tools for managers and decision-makers in various industries to systematically identify and minimize energy waste. It highlights the importance of cross-disciplinary collaboration among specialists in technology, energy consumption, and statistical analysis to optimize energy use. By applying this approach, companies can achieve both financial savings and environmental benefits, contributing to more sustainable production practices.

Nanoparticle deagglomeration driven by a high shear mixer and intensification of low-speed stirring in a viscous system

High shear mixers (HSMs), with their unique advantages of high shear forces and a wide operational range, are commonly used in nanoparticle deagglomeration. This study explores a novel approach to intensifying nanoparticle deagglomeration in a 100 mPa‧s viscous system using HSMs combined with low-speed stirring. The effects of main operating and structural parameters were experimentally investigated. The results show that the teethed HSM outperforms the blade-screen HSM, achieving a smaller attainable size (114 nm vs. 210 nm) and a higher fine particle generation fraction (46.08% vs. 18.77%). Increasing HSM size directly affects the energy input (from 6.478 MJ/kg to 31.879 MJ/kg), which influences the deagglomeration mechanism and kinetics but does not affect the smallest attainable size (117 nm). Higher solid contents improve energy efficiency, while low-speed stirring, though not altering the deagglomeration mechanism, enhances its kinetics. The process intensification factor (S) and energy efficiency factor (εm) were defined to evaluate the intensification of low-speed stirring. Increasing the impeller speed enhances this effect. The PBT impeller with a diameter ratio of 0.35 is identified as the ideal structure in this study, improving deagglomeration performance by 8.26% while reducing energy consumption by 8.3%. These results provide guidance for optimizing processes and improving deagglomeration performance through the combination of low-speed stirring in viscous systems for process industries.

A sustainable waveguide-based design strategy for improving the energy efficiency of microwave hybrid heating systems: A combined theoretical and multi-physics simulation approach

The microwave hybrid heating (MHH) based processing has emerged as energy-efficient and productive manufacturing process. The efficiency of MHH depends upon the ability of waveguide system to transmit the electromagnetic radiation with minimal loss. Thus to improve the efficiency of MHH it is of paramount importance to understand the potential of waveguide systems. In the present work, the influence of different waveguide systems, their positioning, and different modes of operation on MHH efficiency were studied via theoretical and simulation investigations followed by experimental validation. Based on the study, the optimum waveguide system was identified as WR430. To assess the efficiency and effectiveness of the waveguide positioning on MHH, 12 different locations were considered, and the optimum location was identified as (+35, −35), with a maximum microwave utilization efficiency of 44.5 %. Subsequently, the simulation model (1049 °C) was validated using experimental data (1017 °C) with an error of less than 10 %. Also, MHH is sensitive to different waveguide operating modes, SiC susceptor positioning and microwave power. A microwave cavity operating with two waveguides on both sides is found to provide optimum results in terms of heating uniformity, electric field distribution, and microwave energy absorption. The SiC susceptor positioned at the centre of the alumina refractory yields maximum heat evolution of 1020 °C. In addition, as the microwave power grows, the temperature differential also increases, implying thermal heterogeneity inside the SiC susceptor. Thus, low microwave power is identified for improved thermal uniformity and energy efficiency, while high power is proven for rapid differential microwave heating.

Energy Efficiency in Measurement and Image Reconstruction Processes in Electrical Impedance Tomography

Energy Efficiency in Measurement and Image Reconstruction Processes in Electrical Impedance Tomography

4H-SiC Metalens: Mitigating Thermal Drift Effect in High-Power Laser Irradiation.

Enhancing energy density and efficiency in laser processing hinges on precise beam focusing, yet this often causes severe heat absorption and focus shifts in optical lenses. Traditional cooling methods increase cost and complexity, severely limiting versatility. Here, monolithic silicon carbide (SiC) metalens is introduced, which shows unparalleled thermal stability, integrated with a high-power laser. This metalens achieves diffraction-limited focusing with a numerical aperture (NA) of 0.5 and a focal length of 1cm. Under a 1030nm pulsed laser at 15W for 1 h, it shows a minimal temperature rise of 3.2°C and a tiny focal shift of 14µm (0.1% relative), only 6% of the shift in conventional lenses. When used to cut a 4H-SiC substrate with the same laser, the metalens exhibit only an 11.4% change in cutting depth after 1 h of operation, correlating with the focal shift results. The results unveil a groundbreaking class of compact SiC photonics devices nearly impervious to heat absorption, representing a monumental leap for high-power laser systems and opening new horizons for their applications and efficiency.

Liquid-phase CO2 hydrogenation to methanol synthesis: Solvent screening, process design and techno-economic evaluation

This paper focuses on a liquid-phase CO2 hydrogenation process for methanol synthesis to enhance CO2 conversion. The feasibility of a liquid-phase CO2 hydrogenation process is comprehensively evaluated through a techno-economic analysis. The solvent tetraethylene glycol dimethyl ether is identified as one of the most favorable options following an analysis of the solubility data pertaining to various solvents and their influence on the reaction equilibrium of the substances within the system. The influence of process parameters, including temperature, pressure, solvent amount, and gas hourly space velocity (GHSV), on the conversion of CO2 and the selectivity for methanol is examined and optimized in a liquid-phase CO2 hydrogenation to methanol process without a gas recycle (Process 1), optimal reaction conditions are determined and a CO2 conversion of 95.19 % and a CH3OH yield of 94.77 % with a purity of 99.9 % are achieved. A liquid-phase process with a gas recycle (Process 2) is implemented to enhance the utilization of feed gas, achieving a CO2 conversion rate of 95.23 % and a methanol yield of 99.69 %. The liquid-phase process is further optimized by incorporating reactive distillation technology (Process 3), to enhance reaction efficiency and reduce energy consumption. Following the techno-economic evaluation, the energy efficiency of Process 3 is 7.79 % and 4.99 % higher than that of Process 1 and Process 2, respectively. The product cost of Process 3 is reduced by 8.75 % compared to Process 1 and by 4.25 % compared to Process 2. This research offers insights into the challenges associated with the development of the liquid-phase method.

High-flux polyamide thin-film composite membranes consisting of Tröger's base motif with enhanced microporosity for nanofiltration

High-flux and selective membranes are key components to improving the energy efficiency of nanofiltration processes for water purification. Herein, we report high-flux polyamide thin-film composite (TFC) membranes consisting of Tröger's base for nanofiltration. Tröger's base diamine (TBD) was synthesized as an aqueous phase monomer for interfacial polymerization. Detailed characterization of TBD-based polyamides was performed using thermal, spectroscopic, and microscopic analyses. Notably, the V-shaped and rigid Tröger's base motif rendered TBD-based polyamide (named TBD-TMC) features with enhanced microporosity as well as an enlarged pore size compared to conventional polyamide chemistry (i.e., MPD-TMC). As a result, the TBD-TMC membrane exhibited a 570 % improvement in water permeance compared to MPD-TMC membranes while exhibiting moderate salt rejection up to 91 %, outperforming most reported nanofiltration membranes. Also, the TBD-TMC membrane exhibited high monovalent/divalent ion selectivity (∼7.0 for NaCl/Na2SO4 separation), which may have resulted from the combined effects of size exclusion and charge repulsion. This work highlights the potential of Tröger's base motif as a new diamine monomer for interfacially polymerized membranes to tune their microporous structures.

Comprehensive Strategies for Addressing Tube and Tubesheet Joint Leaks in Shell-and-Tube Heat Exchangers

Heat exchanger tube leakage severely affects the ability of the heat exchanger to maintain its process temperature and energy efficiency. A comprehensive strategy for heat exchanger repair is presented, focusing on addressing leaks of varying types and locations within the tubesheet. The approach considers the historical context of recurring leaks to formulate repair decisions effectively. Techniques such as tube plugging, installation of weld plug, and double plug for tubesheet joint leaks are demonstrated. Moreover, the implementation of individual tube hydro testing and insurance plugging is highlighted to ensure sustained heat exchanger functionality. A novel aspect of this paper is the inclusion of a decision-making flowchart, offering practical guidance to plant personnel encountering diverse leak scenarios in the industrial process. By integrating historical data and considering leak specifics, plant maintenance teams can streamline repair processes, thereby optimizing heat exchanger performance and longevity in various industrial applications.