Search Results (4,677)

Ensuring the required microclimate parameters is the most critical task in hot climates. In pig farms, air cooling is provided by means of steam-compression chillers or evaporative cooling, which is the simplest way to cool the air. The implementation of evaporative cooling depends largely on the interaction of the media involved in this process. This paper considers the process of interaction of cooling water with the surface of a cellular polycarbonate heat exchanger. A mathematical model describing the process of wetting the sprayed surface of the heat exchanger is obtained. The authors determined the theoretical water flow rate required to provide air cooling for a given operation mode. Experimental trials of a recuperative heat recovery unit with a heat exchanger made of cellular polycarbonate equipped with a water evaporative cooling system were carried out. The authors conducted a comparative assessment to evaluate the effectiveness of evaporative cooling in a heat recovery unit equipped with a polycarbonate heat exchanger versus panel evaporative systems using wetted paper pads at pig farms in the Vladimir and Tambov regions of Russia. The panel evaporative coolers provided a temperature reduction of 11.3 °C without any splashing effect. Under the same operating conditions, the heat recovery unit achieved an inlet air temperature reduction of 10.5 °C, accompanied by splashing. When the water flow rate supplied for evaporation was reduced until the splashing ceased, the cooling temperature drop decreased to 10.1 °C, which is 11% lower, compared with the paper pads. The study revealed characteristic operating modes for the unit that ensure effective air cooling, depending on the cooling water flow rate. Since the prevailing temperature during the system’s main operating time is significantly lower than the design temperature (the absolute temperature maximum), to achieve effective cooling of the supply air without splashing or excessive water waste, the cooling circuit water should circulate at a flow rate within 40 to 63% of the maximum design value. Alternatively, an automated control system should be employed to regulate the water supply based on outdoor air temperature and humidity. Full article

An electrical heating fluidized-bed thermal energy storage (EH-FB-TES) system is proposed for integration with a coal-fired power plant (CFPP) for deep peak shaving (DPS) due to its high energy storage density and extensive heat exchange performance. The primary objective of this study is to evaluate the thermodynamic performance and economic feasibility of the integrated EH-FB-TES system, specifically focusing on identifying the optimal coupling and heat recovery strategies for enhanced deep peak shaving performance. Since EH-FB-TES uses air flow for fluidization in the heating storage process, its coupling with the CFPP differs from other TES technologies, and the associated thermodynamic performance and cost are thereby analyzed. The results show that, in EH-FB-TES, the heat release efficiency is predominantly constrained by thermal losses. To increase the energy utilization efficiency, a two-stage heat recovery strategy is proposed to release the stored energy in the integration. The first stage is to heat up the feedwater extracted from the deaerator and the second one is to heat up the condensate water. The analyses also show that the selection of reinjection positions for the heated medium from EH-FB-TES greatly influences the system performance. Returning the stored thermal energy to heat up feedwater can effectively increase the output of the unit, while directly generating steam can be beneficial for coal saving. The integrated system achieves a maximum equivalent round-trip efficiency of 32.9% under 20 MW/800 °C conditions. An economic analysis reveals that, compared with other energy storage methods, EH-FB-TES can realize a relatively high energy storage density with a rather low cost. Under the present DPS compensation policy, for a 315 MW subcritical CFPP integrated with a 50 MW EH-FB-TES system, when heat storage is 8 h, heat release is 4 h per day, and the plant operates 100 days per year, the estimated static and dynamic payback periods are 3.06 years and 3.67 years, respectively. The integration of CFPP with EH-FB-TES could be promising for meeting DSP requirements. Full article

Background: Chronic Obstructive Pulmonary Disease (COPD) is a common condition that can cause dyspnea, pain, and biomechanical-postural alterations, especially when overlapping with Myofascial Pain Syndrome (MPS). Balneological rehabilitation medicine can help manage COPD and MPS, but it lacks homogeneity and detailed descriptions of effective therapeutic protocols. Therefore, we conducted a case series to preliminarily evaluate the clinical effects of a detailed and codified approach, called Bio-Physico-Metric Integrated Thermal Care (BPM-ITC), for COPD+MPS. Methods: 10 patients were observed while undergoing 20 sessions of BPM-ITC in 4 weeks. Patients were assessed before and after the protocol using the Medical Research Council (MRC) dyspnea scale, Numeric Pain Rating Scale (NPRS), and the Bio-Postural Questionnaire (BPQ) for bio-physical health status. Treatments included manual therapy of key myofascial trigger points combined with crenotherapy, steam inhalations, mud therapy, vascular path, and water-based motor re-education. Results: At the end of the protocol, clinically relevant improvements were observed in almost all parameters considered in single observed cases; overall statistical analysis of the data highlighted significant positive effects in concomitance with the BPM-ITC protocol. Conclusions: The BPM-ITC protocol was followed by significant clinical improvements in the observed cases, suggesting its potential as a complementary approach for COPD+MPS. Further studies on this topic are recommended. Full article

Bayberry (Morella rubra Lour.; syn. Myrica rubra (Lour.) Siebold & Zucc.) leaves are rich in bioactive compounds but remain underutilized. This study investigated the optimal harvest stage and processing methods to develop high-quality functional powder. We first compared three growth stages: red buds (RB), new leaves (NL), and old leaves (OL). RB exhibited the highest antioxidant capacity and unique volatile profile; however, NL was selected for processing optimization due to the balance between quality and biomass availability. Subsequently, NL was subjected to freeze-drying (FD), mechanical drying (MD), steaming followed by MD (S-MD), and shade drying (SD). Results showed that FD preserved the vibrant green color, glandular trichome structure, ascorbic acid, and fresh volatiles (monoterpenes). Conversely, thermal drying (MD and S-MD) disrupted cellular barriers, which facilitated the extraction of minerals and robust polyphenols like myricitrin, yielding the highest extraction of flavonoids and corresponding antioxidant activity, measured by hydrophilic oxygen radical absorbance capacity (H-ORAC), in hot water extracts than FD. SD significantly degraded quality due to prolonged enzymatic oxidation. While FD is ideal for preserving aesthetics and heat-sensitive nutrients, low-cost MD and S-MD are recommended for producing antioxidant-rich powders for functional food applications where extraction efficiency is prioritized. Full article

Hydraulic dynamometer is the key equipment to measure the dynamic performance of high-power gas turbines and steam, with its internal flow characteristics directly influencing measurement accuracy and service life. This paper focuses on the power absorption performance and internal flow characteristics of a hydraulic dynamometer with perforated-disk rotor. A hydraulic test platform is established to measure the power absorption performance of megawatt-level hydraulic dynamometers. When the rotor speed reaches a certain value under the full-water condition, the power absorption of the hydraulic dynamometer reaches its limit. Numerical simulations are applied to study the internal flow characteristics and cavitation evolution features of the perforated-disk-type hydraulic dynamometer. The flow within the outermost rotor pores is the primary factor influencing unsteady flow behaviour, with dynamic–static interference playing a key role in inducing flow excitation. Moreover, cavitation mainly occurs in the flow passages of the end rotor and the outermost flow pores of the middle rotor, where the development and collapse of cavitation bubbles lead to flow instability. As the rotation speed decreases, the power absorption performance significantly decreases under cavitation conditions. These findings provide a theoretical basis for the structural optimization and engineering application of high-power hydraulic dynamometers. Full article

The application of ultra-supercritical power plant boilers is becoming increasingly widespread. P92 steel, as a typical material used for boiler main steam pipes, plays a critical role in unit safety, making the detection of its creep damage highly significant. However, existing conventional non-destructive testing methods are difficult to effectively detect creep damage. To address this issue, a magnetoacoustic emission (MAE)–magnetic Barkhausen noise (MBN) composite measurement system is developed, which is adapted to 20 Hz and 0.3 A sine wave excitation to trigger the synchronous pickup of MBN and MAE signals of P92 steel. After collecting signals with different creep life ratios (0%~100%) under working conditions of 650 °C and 100 MPa, time-domain (absolute mean, peak value, etc.) and frequency-domain (bandwidth) features are extracted. In response to the non-monotonicity between the magnetoacoustic features and the creep damage grade, principal component analysis (PCA) is introduced to reduce dimensionality. Different creep levels of samples in the two-dimensional principal component space are presented as clear gradient clustering, achieving the accurate differentiation of creep stages. Research has shown that the MAE-MBN composite system combined with PCA can effectively characterize the creep damage of P92 steel, providing a novel non-destructive detection path for the in-service life assessment of power plant components. Full article

The rapid expansion of the poultry industry has led to the large-scale generation of feather waste, creating serious environmental and public health concerns due to the recalcitrant nature of keratin. Poultry feathers are composed mainly of highly cross-linked keratin proteins stabilized by numerous disulfide bonds, which confer resistance to conventional proteolytic enzymes and natural degradation processes. This review examines the potential of keratinolytic fungi and their enzymes as sustainable, eco-friendly, and value-added strategies for poultry feather waste management and resource recovery. It discusses the environmental and health risks associated with improper feather disposal, such as pathogen proliferation, odor generation, and ecosystem contamination. Conventional management approaches, steam pressure hydrolysis, mechanical grinding, thermal treatment, acid–alkali hydrolysis, and oxidation, are critically evaluated in terms of efficiency and environmental impact. The review further highlights biological degradation pathways mediated by keratinolytic fungi and enzymes, with emphasis on fungal genera such as Aspergillus and Chrysosporium. Key mechanisms of fungal keratin degradation, including sulfitolysis, proteolysis, deamination, hyphal penetration, enzyme secretion, and biofilm formation, are discussed. Finally, industrial, agricultural, and feed applications of keratinases, along with advances in strain improvement, omics technologies, synthetic biology, and associated biosafety and regulatory considerations, are addressed. Full article

Methane oxy-combustion is a promising carbon capture pathway due to the high CO₂ concentration in the exhaust; however, combustion in pure oxygen produces excessively high flame temperatures that impair ignition and operational stability. To mitigate these effects, steam dilution is commonly applied, but it significantly prolongs ignition delay time (IDT). To address these limitations, hydrogen enrichment is proposed as a reactivity-enhancement strategy. The objective of this study is to quantify the combined effects of steam dilution and hydrogen enrichment on ignition behaviour, carbon species formation, and flame temperature in methane oxy-combustion, considering both ignition onset and equilibrium combustion states. A detailed numerical investigation is conducted using zero-dimensional constant-pressure simulations with detailed chemical kinetics implemented in Cantera, formulated in mixture-fraction space. IDT, CO/CO₂ formation, and adiabatic flame temperature are analysed over steam dilution levels of 0–40%, hydrogen enrichment up to 5% by mass, and initial temperatures between 1050 and 1200 K. The model is validated against experimental data for adiabatic flame temperature and key radical species. Results demonstrate that steam dilution effectively reduces the peak adiabatic flame temperature (by more than 300 K at 40% steam) and enhances the CO₂ mass fraction in the equilibrium state near the stoichiometric mixture fraction, but increases IDT by approximately 100–200% across the mixture-fraction range. Hydrogen enrichment strongly counteracts this inhibition, reducing IDT by up to one order of magnitude under high steam dilution (30–40%) while simultaneously suppressing CO. At the stoichiometric mixture fraction, H₂ addition decreases equilibrium CO₂ formation, indicating a trade-off between enhanced ignition reactivity and ultimate carbon conversion under equilibrium conditions. The use of steam dilution as a temperature-control strategy and hydrogen enrichment as a reactivity enhancer identifies a favourable mixture-fraction window. Full article

To investigate the influence of asymmetric support clearances (caused by manufacturing and assembly tolerances in practical engineering) on the fretting wear behavior of steam generator heat exchange tubes, this study focuses on 2.25Cr-1Mo alloy heat exchange tubes and 405 stainless steel anti-vibration bars. A high-precision impact wear test platform with adjustable bilateral clearances was designed, and its dynamic reliability was verified by theoretical calculations, finite element simulations and modal tests. An experimental model with asymmetric clearances (0.15 mm and 0.20 mm) was established to study the nonlinear contact force response and wear evolution under excitation frequencies of 60 Hz, 65 Hz and 70 Hz. The results show that asymmetric clearances induce two contact modes: high-frequency “quasi-static friction” on the small-clearance side and intermittent “collision-rebound-flight” impacts on the large-clearance side. The system exhibits a clear excitation instability threshold that shifts backward with increasing excitation frequency. The 0.20 mm side triggers dynamic instability, with wear volume and rate increasing explosively (106.2% and 41.36% at 65 Hz) beyond the threshold. Microscopic analysis reveals that the wear mechanism on the large-clearance side transitions from mild abrasive wear to severe fatigue delamination when crossing the threshold, with surface morphology deteriorating sharply from faint contact spots to extensive spalling craters. This study clarifies the energy distribution mechanism and identifies the large-clearance side as the core “trigger” for system instability and catastrophic failure, providing a theoretical basis for nuclear heat exchange tube monitoring and anti-vibration design. Full article

This paper presents a thermodynamic modelling and performance analysis of a 217 MW coal-fired steam power plant, based on operating data from the only currently active coal-fired unit in Croatia. The study provides a concise technical description of the plant and a detailed thermodynamic analysis of energy flows across all major components of the steam cycle. The analysis was carried out using two complementary approaches: analytical calculations based on standard thermodynamic balance equations and numerical simulations performed with the commercial software Ebsilon Professional Version 17.00. The results obtained by both methods were validated against data reported in the literature and showed deviations within acceptable limits. Using the validated model, the influence of the number of regenerative feedwater heaters on overall plant efficiency was analysed. Additionally, sensitivity analyses were conducted to evaluate the influence of selected parameters, including the fuel net calorific value (NCV), the terminal temperature difference (TTD) of feedwater heaters, and pressure drops within the regenerative system. The results show that increasing the TTD from 2 K to 8 K reduces the net thermal efficiency from approximately 37.01% to 36.79%, while variations in pressure drop have a negligible effect on plant performance. Finally, a CO₂ emission cost analysis was conducted for each configuration, and conclusions regarding efficiency improvement and emission reduction were drawn. It was found that removing any regenerative feedwater heat exchanger decreases the observed overall plant efficiency by approximately 0.55% on average and increases plant CO₂ emissions by approximately 0.025 Mt per year on average. Full article

In China, antibiotic fermentation residue has been listed as a “hazardous waste” due to its high residual concentrations of antibiotics. There are many ways to deal with antibiotic fermentation residue; however, effective methods are still lacking. In the present work, steam explosion (SE), thermal, and aerobic composting treatments were performed to investigate the resource utilization of cephalosporin C fermentation residue (CFR). The results show that 0 mg/kg, 50.2 mg/kg and 150.5 mg/kg cephalosporin C (CEPC) remained after the SE, composting, and thermal treatments. The total abundance of antibiotic resistance genes (ARGs) decreased by 62.2% and 47.2% after the SE and thermal treatments and increased by 1.4 times in the samples subjected to composting. Nitrogen analysis showed that the nitrogen loss (N loss) was only 1.9% in the SE-treated samples. The antibiotic inhibition zone was reduced by 80.3%, 71.2% and 40.8% in the samples subjected to SE, composting, and thermal treatments. LC/MS showed that the β-lactam ring and dihydrothiazine ring of CEPC were largely destroyed via SE. These results suggest that the SE treatment not only decreased the residual cephalosporin and ARG levels and antimicrobial activity but also preserved most of the nitrogen. SE is therefore a feasible treatment that can be used to deal with CFR. Full article

The application of multi-cycle steam stimulation in heavy oil reservoirs frequently alters reservoir properties, influencing the effectiveness of the stimulation and subsequent development strategies. The inherent heterogeneity of strata, characterized by distinct sedimentary facies rhythms, leads to differential patterns of property evolution. Therefore, understanding facies-controlled property variations during steam stimulation is essential for optimizing recovery strategies. This study integrates 1D core experiments with 3D geological modeling to dynamically simulate the stimulation process, enabling a comprehensive multi-scale analysis. The results show the following: (1) Both sedimentary rhythms exhibit progressive increases in porosity and permeability with successive cycles until reaching stabilization plateaus, with the uniform rhythm stabilizing earlier than the coarsening-upward rhythm. (2) 3D simulations reveal a predominant increasing trend in porosity and permeability after multi-cycle stimulation, albeit with localized reduction zones. (3) Multi-scale analysis indicates that, during the early stage (cycles 1–9), the underwater distributary channel microfacies undergoes more rapid property changes and achieves a greater cumulative increase in porosity and permeability. Conversely, during the later stage (cycles 10–30), the mouth bar microfacies demonstrates faster property alterations and a larger cumulative enhancement. This facies-specific, time-dependent understanding provides critical insights for tailoring steam stimulation strategies in heterogeneous heavy oil reservoirs. Full article

The current understanding of microbiota–flavor correlations in Chinese sourdough steamed bread is predominantly derived from the central provinces, with comparatively limited investigation in northeastern and northwestern regions. This study bridges this gap by analyzing traditional starters from Heilongjiang (HLJ) and Ningxia (TX) versus an industrial starter (JM) through integrated metagenomics and untargeted metabolomics. HLJ was dominated by Limosilactobacillus fermentum (14.75%), while TX featured a synergistic Lactiplantibacillus plantarum–Fructilactobacillus sanfranciscensis consortium. Metabolic pathway analysis revealed enhanced glycolysis, amino acid metabolism, and glycerophospholipid transformation driving flavor biosynthesis and dough rheology improvement, supported by nitrogen-metabolizing Bradyrhizobium spp. (6.00–6.61%). Core pathway enrichment established molecular foundations for region-specific flavors: HLJ generated sulfury/pungent notes via the enzymatic conversion of pentyl glucosinolate to isothiocyanates, whereas TX developed caramel–roasted aromas through stachyose/xylose-derived Maillard reactions forming 2-(methylthiomethyl)furan. Both consortia exhibited higher bitterness and lower umami than JM, with HLJ showing marginally higher umami and lower bitterness than TX. These findings elucidate the microbial mechanisms underlying regional flavor differentiation. Full article

Increasing global demand for animal-based protein has created a critical environmental management challenge regarding manure accumulation in intensive livestock production. Gasification offers a sustainable solution by converting organic residues into renewable synthetic gas (syngas) and carbon-rich biochar. This study systematically evaluated the performance of three major types of animal waste—dairy manure, poultry litter, and swine manure—against a lignocellulosic control (wood veneer waste) in a top-lit updraft (TLUD) gasifier. Three airflow rates (10, 15, and 20 L min⁻¹) were studied. The results indicated that increasing airflow significantly elevated the gasifier flame front temperatures, with poultry litter achieving the highest peak temperature (825.5 °C), followed by swine manure and dairy manure (753.7 and 727.0 °C, respectively) at 20 L min⁻¹ airflow. While dairy manure exhibited the fastest linear burning rate (25.7 mm/min), poultry litter demonstrated the highest mass consumption rate (32.8 g/min). Feedstock chemistry drove distinct reaction pathways in syngas composition. Poultry litter emerged as the superior feedstock for H₂ production, achieving a peak H₂ concentration of 10.78% at 20 L min⁻¹, which attributed to a synergistic combination of outstanding temperature, moisture content and catalytic alkali metals that promoted steam reforming and water–gas shift reactions. CO production was dominated by wood veneer (17.6%), which was driven by the dominance of elemental carbon and fixed solid (FS) content that favored partial oxidation and a Boudouard reaction. These findings suggest that while airflow regulates thermal kinetics, the specific energy profile of the produced syngas is fundamentally determined by the physiochemical properties of the biomass precursor. Full article

This study aimed to valorize by-products from cabbage processing to produce nutrient-rich powders that are suitable for food incorporation and, as a case study, to evaluate their application in texture-modified jelly intended for senior consumers. Freeze-dried powders from cabbage leaves and cores were analyzed for physicochemical properties, nutritional value, and antioxidant activity. Steaming significantly affected water absorption, solubility, and color: powders from fresh cabbage exhibited higher water solubility and lighter, greener hues, whereas powders from steamed cabbage showed darker, yellow–red tones due to pigment degradation. Nutritional analysis confirmed high dietary fiber contents (>30 g/100 g dry weight) in all powders. Core powders contained more potassium and phosphorus, with minimal mineral losses being observed after steaming. Sugar profiling showed greater fructose, glucose, and total sugar contents in leaf powders, whereas sucrose predominated in core powders. Steaming facilitated maltose formation. Although steaming generally reduced total phenolic content, it increased antioxidant activity in steamed leaf powders. Application trials demonstrated that cabbage powder concentrations strongly influenced jelly composition, including dietary fiber, total phenolic content and mineral levels, while pectin concentration primarily affected texture. Optimized formulations yielded nutritionally enriched jellies with acceptable sensory properties, demonstrating the feasibility of using cabbage processing by-products as a value-added food ingredient. Full article