Fructus aurantii, a genuine traditional Chinese medicinal material, undergoes drying as a critical step to ensure the quality of its post-harvest processing at the origin. However, a major challenge in this process are the uneven drying rates between the surface and interior, which often leads to quality defects such as dry and wet spots. In severe cases, it can even cause localized mold growth, significantly compromising the processing quality and market value of the product. To address this issue, this study systematically characterized the microstructure of Fructus aurantii using CT scanning technology, developed a more realistic microstructure model, and accurately obtained key physical parameters including pore structure properties. Based on this microstructure characterization, a transient heat and mass transfer model for the drying process of Fructus aurantii was established and solved numerically. Model validation experiments were performed under drying condition at 55 °C, and the results showed that the maximum deviation between the simulated and experimental moisture ratio values was only 9.2%, confirming the model’s reliability. Using this basis, the dynamic evolution of internal temperature distribution, moisture content distribution, and water vapor partial pressure gradient during drying were thoroughly analyzed. It was found that the low-porosity structure of the Fructus aurantii surface significantly hinders moisture diffusion. Moisture accumulates at the interface between the surface and the fiber layer, leading to the formation of wet spots. Conversely, in the non-aggregated regions between the surface and internal fibers, dry spots tend to form due to restricted moisture diffusion combined with a high evaporation rate. This study systematically reveals the core mechanism of internal moisture migration during the drying of Fructus aurantii, providing important theoretical support for the optimal design of mold-prevention and quality-enhancement drying processes, as well as related engineering innovations for this medicinal material.

Sludge dewatering is a critical step in wastewater treatment, but conventional methods often rely on high chemical dosages and energy-intensive mechanical processes while achieving only limited moisture reduction. Recent advances such as bio-flocculants and electro-osmotic dewatering have improved dewatering performance, yet these techniques are constrained by high costs, inconsistent efficacy, or excessive energy use. Moreover, their impact on downstream thermal drying equipment performance remains underexplored, representing a significant research gap. To address this gap, this study develops a simulation-driven framework that links upstream moisture content reduction to heat pump drying efficiency. Using a low-concentration cationic polyacrylamide (CPAM) flocculant (0.01% dose) for sludge pretreatment, we reduced sludge moisture content from 82.7 to 22.7% and evaluated the effects on a subsequent heat pump dryer. The results show that this optimized pretreatment increased the heat pump’s coefficient of performance (COP) by 37.8% and extended its maintenance interval by 42.3% relative to untreated sludge. This low-dose chemical approach achieved greater efficiency gains than traditional high-dose flocculation methods, with a conventional aluminum sulfate treatment (15 mg/L) yielding a 33.2% COP improvement. The integrated model also predicts substantial operational cost savings of around $27,450 per year per heat pump unit under the optimized CPAM treatment. These findings demonstrate the significant energy and economic benefits of linking advanced dewatering pretreatment to downstream thermal processing performance. By quantifying these cascading benefits, the study introduces a novel and more sustainable strategy for sludge management, bridging the gap between sludge dewatering innovations and improved thermal equipment efficiency.

Recent studies have increasingly highlighted the critical role of interfacial electrochemical reactions in electroosmotic processes. However, existing theoretical frameworks often fail to adequately capture the coupling between electrochemical reactions and electroosmosis, while experimental approaches struggle to directly characterize the evolving electrochemical behavior. In this study, Linear Sweep Voltammetry (LSV), an advanced technique capable of directly capturing electrochemical reaction characteristics, was employed to investigate the interfacial potential. From an electrochemical perspective, the interfacial potential was shown to comprise an equilibrium potential and multiple overpotentials, including activation, concentration, and Ohmic components. The results demonstrate that the equilibrium potential plays a decisive role in electroosmotic initiation. When the anodic potential remains below the equilibrium potential, no current is generated, demonstrating the absence of both electrochemical reactions and electroosmotic flow. As electroosmosis proceeds, the contribution of the anodic equilibrium potential increases progressively, accounting for 16%–23% of the total potential drop. Polarization curve analysis further confirms the coexistence of multiple overpotentials beyond the Ohmic component. Compared with a conventional electrolysis system, the electroosmotic system exhibits a substantially higher anodic potential drop, primarily attributed to enhanced concentration and activation overpotentials. Moreover, the evolution of polarization resistance closely follows the early-stage current response, providing additional evidence for the dominance of concentration overpotential. Building on the clarified composition of the anodic potential, this study validates the feasibility of using the anodic potential drop as a reliable indicator of electroosmotic drainage performance. A strong correlation with drainage rate is established, confirming its practical applicability as an engineering indicator. These findings provide new insights into the electrochemical mechanisms governing electroosmosis and offer a foundation for integrating electrochemical reaction dynamics into the optimization of electroosmotic systems.

Refractance Window Drying (RWD) is an emerging thin-film drying technology for heat-sensitive foods. In this process, liquid or semi-liquid materials are spread in a uniform thin layer on an infrared-transparent polymer film in contact with circulating hot water. This enables rapid moisture removal at moderate product surface temperatures (60–70 °C range). Compared with conventional hot-air drying (HAD), RWD reduces drying times from hours to minutes while effectively preserving color, thermolabile nutrients, antioxidants, and phenolic compounds. The resulting product quality is reported to be comparable to freeze-drying (FD), but with substantially lower energy consumption and capital investment. RWD has been successfully applied to fruit and vegetable purees, powders, dairy-based formulations, and plant- and animal-derived protein systems. Recent developments in hybrid RWD configurations, incorporating infrared heating, vacuum conditions, microwave assistance, and pretreatments such as osmotic dehydration, ultrasound, and cold plasma, have further enhanced RWD efficiency and product quality. Despite these advantages, challenges related to scale-up, feed-layer uniformity, and process control remain under active investigation. Overall, RWD represents a sustainable, high-performance drying technology with strong potential for high-value food and bioactive applications.

The present investigation aimed to find the optimal conditions for the spray drying conditions of finger millet milk blended with jamun juice, with a novel approach of producing the powder without any additional carrier agents. A three-factor three-level RSM design was employed to optimize inlet spray drying temperature (T; 150-170 °C), ratio of millet milk to jamun juice (MJ; 1–3) and flow rate (FR; 150–250 mL/h) based on powder yield, color change (ΔE), total phenolic content (TPC), DPPH assay (DPPH) and solubility (S). The optimum drying conditions were determined as 150 °C inlet spray drying temperature, 212.89 mL/h flow rate and 1:1 MJ ratio, yielding a desirability of 0.995. Under these conditions, the product showed a powder yield of 34.07%, high total phenolic content (119.34 g GAE/100g), 80.13% DPPH, ΔE of 22.84 and solubility of 55.02%. Structural and molecular characterization of the optimal powder using SEM, XRD and FTIR confirmed amorphous morphology with retained bioactive compounds. The developed product contains the nutritional benefits of both finger millet and jamun, offering potential for use in the development of value-added food products.

Washed municipal solid waste incineration (MSWI) fly ash typically leaves the washing unit as a cohesive, high-moisture cake, and a subsequent drying step is often required to enable safe handling, transport, and downstream stabilization/solidification. This study applies vacuum drying to washed fly ash using a static vacuum dryer. We investigate how heating temperature (80 °C–140 °C), vacuum level (gauge pressure ranging from 0 to −0.08 MPa), and fly ash layer thickness (3.4–13.6 mm) affect drying behavior, kinetics, and mechanisms. Temperature and layer thickness are the dominant factors controlling the drying rate, while the influence of vacuum level is moderate but non-negligible. A mild-to-moderate vacuum accelerated drying by lowering the equilibrium boiling temperature and sustaining a large vapor-pressure driving force, whereas excessively strong vacuum tended to promote early surface stiffening and crust formation, and thereby limited internal moisture transport. From the fitted kinetics, an apparent effective diffusivity and an Arrhenius-type apparent activation energy were estimated; E a decreased from 44 kJ/mol in the early stage to 15 kJ/mol in the late stage. Time-lapse imaging revealed substantial shrinkage and crack development: higher temperature and greater thickness promoted main cracking, while pressure primarily regulated fine cracks (milder vacuum produced denser fine cracks; deeper vacuum yielded fewer, larger cracks). These findings provide practical insights for optimizing vacuum drying of washed incineration fly ash, aiding in its safe reuse or disposal and contributing to resource utilization and environmental protection.

This study introduces a hybrid drying system that incorporates an air-to-air heat recovery unit with infrared heating film (IRHF) technology, experimentally evaluated under classical (on-off), proportional-integral (PI), and adaptive firing angle (AFA) control modes through seven trials on zucchini fruit (Cucurbita pepo L.). Results demonstrate that adaptive control consistently outperforms traditional modes by achieving a favorable balance between efficiency, energy savings, and product quality. Notably, Experiment 5 and Experiment 6 achieved the highest efficiency gains (25.19% and 23.72%), while Experiment 7 delivered remarkable energy savings (78.55%) despite a 21.63% longer drying time. Experiment 4 provided the best overall balance, with 13.44% higher efficiency, 56.73% shorter drying time, and 57.04% energy savings. Experiment 3 offered a conservative option, maintaining visual quality with 45.41% energy and 35.21% time savings. Overall, adaptive protocols enable flexible optimization: aggressive settings maximize energy recovery, while conservative ones safeguard product esthetics. The proposed system highlights the systematic advantages of adaptive algorithms in managing the “efficiency–energy–quality” tradeoff, offering scalable and environmentally conscious solutions for agricultural post-harvest processing.

This article presents a digital twin-enabled framework for modeling and control of wood drying in a Desiccant-Assisted Heat Pump (DAHP) system. The digital twin integrates high-fidelity physics-based models of the heat pump, kiln chamber, and wood moisture–stress behavior, capturing coupled heat and mass transfer processes critical to drying performance. Leveraging the digital twin as the environment, the drying process is cast as a Decentralized Markov Decision Process (Dec-MDP) and addressed through Multi-Agent Reinforcement Learning (MARL). The proposed approach reduces total site energy consumption by 43.2%, shortens drying duration by approximately eight days, and decreases carbon intensity by up to 94% relative to a conventional boiler-based baseline. To enhance interpretability and support industrial deployment, a heuristic policy distilled from the MARL control achieves comparable performance. By coupling digital twin modeling with advanced learning-based control, this study establishes a deployable pathway toward sustainable, energy-efficient, and high-quality wood drying, with broader implications for next-generation smart manufacturing and energy systems.

This study optimized the synergistic use of powdered activated carbon (PAC) and ultrasonication (US) for sludge dewatering via response surface methodology. Results identified optimal conditions (43% PAC, 9.3 W/L US, 43 s) and revealed that treatment sequence critically determined performance. US followed by PAC achieved a sludge cake moisture content of 63.52% and specific resistance to filtration of 2.293 × 1011 m/kg, improving raw sludge values by 35.5% and 97.2%, respectively. Conversely, the reverse sequence degraded efficiency. SEM indicated that US pretreatment disrupts extracellular polymeric substances, releasing bound water, while subsequent PAC creates permeable channels. This sequence-dependent synergy underscores the importance of operational optimization for energy-efficient conditioning, offering a viable strategy to reduce sludge disposal costs and environmental footprint, despite persisting challenges like PAC cost and reactor design.

Drying efficiency, temperature uniformity, and dried product quality are three crucial indicators for evaluating the performance of a drying process. To enhance these aspects and minimize the loss of samples, a pilot-scale radio frequency (RF) system, operating at 27.12 MHz and 6 kW and combined with hot air, was employed to dry cauliflower with both uniform density (where the cauliflower had the same density) and combined densities (where the cauliflower had different densities in different zones) in a rectangular container. During the hot air-assisted RF drying process, the temperatures of the cauliflower with both uniform and combined densities initially increased, subsequently decreased, and then increased again. Due to the higher electrical intensity at the corners and edges of the container, the highest temperatures were observed there, while the center exhibited the lowest temperatures. In contrast, the moisture content of the samples displayed an opposite pattern. After the drying process, samples with a combined density exhibited better heating uniformity than those with a uniform density, as indicated by the lower heating uniformity index. As the total drying times of the samples with uniform and combined densities were 285 min and 240 min, respectively, the samples with the combined density exhibited higher drying efficiency. The drying process of the samples was described by the logarithmic model. After the drying process, the dried samples with a combined density showed lower total color difference (ΔE) and lower vitamin C loss rates than those with a uniform density (p < 0.05). The results of this research offer valuable insights into the drying samples with high moisture content during RF drying technology.