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Processes

Processes is an international, peer-reviewed, open access journal on processes/systems in chemistry, biology, material, energy, environment, food, pharmaceutical, manufacturing, automation control, catalysis, separation, particle and allied engineering fields published semimonthly online by MDPI.
The Brazilian Association of Chemical Engineering (ABEQ) is affiliated with Processes and its members receive discounts on the article processing charges. Please visit Society Collaborations for more details.

All Articles (19,327)

This study adopted statistical optimization designs to identify the optimum input processing factors for estimating oil output parameters and deformation energy. The mechanical properties—namely, hardness and the secant modulus of elasticity—were also examined. Based on the full quadratic model, including the significant and non-significant terms, the optimal input processing factors were determined to be a heating temperature of 60 °C, a heating time of 52.5 min, and a sample pressing height of 60 mm, with R2 values ranging from 0.68 to 0.95. The linear models with only the significant terms predicted a mass of oil of 33.36 g, an oil yield of 21.5%, an oil expression efficiency of 65.47%, anda deformation energy of 1080.82 J. The hardness and secant modulus of elasticity values ranged from 3.65 to 7.09 kN/mm and 123.98 to 150.39 MPa, indicating that the varying input processing factors had a significant effect on the stiffness of the bulk hemp seeds. The tangent curve model showed reliability in estimating the theoretical deformation energy, which was closer to the experimental deformation energy. These findings are useful for modelling and optimizing the mechanical behaviour of oilseeds using a mechanical screw press to enhance oil extraction efficiency.

11 February 2026

(a) Uniaxial compression test for extracting the oil; (b) seedcake of bulk hemp seeds sample afer compression tests; (c) extracted oils from the 17 experimental tests/runs conducted.

Surface defects are frequently observed in calendered polyvinyl chloride (PVC) films. Their evaluation in production environments is typically qualitative and operator dependent. Using the common gas entrapment defects as the test case, the present study develops a four-step image-processing workflow that converts scanned film images into pixel intensity matrices and groups defect pixels using density-based clustering (DBSCAN). The procedure provides quantitative measures of defect count, size, and spatial distribution without manual labeling. The effects of roll gap, calendering speed, upstream mixing time, and plasticizer type were examined under controlled conditions. Larger roll gaps and higher speeds reduced degassing efficiency and increased both defect number and defect area. Short mixing times led to incomplete gelation and higher defect frequency. Among the tested plasticizers, TOTM produced the lowest defect counts, followed by DEHP and ESBO. Design-of-experiments analysis ranked parameter sensitivity and identified operating ranges that limit defect formation. The method provides a practical basis for routine surface inspection and supports process adjustment using measurable defect metrics rather than visual judgment alone.

11 February 2026

Schematic representation of the calendering process, illustrating melt entry into the nip, compression between rolls, bubble nucleation, and the formation of surface defects after solidification. Arrows indicate the direction of film transport through the calender rolls.

This study investigates the impact of ethanol as a co-solvent in hydrothermal carbonization (HTC) of sewage sludge, a process referred to here as ethanothermal or solvothermal carbonization. Experiments were conducted at 180 °C, 200 °C, 220 °C, and 240 °C, comparing two sets of conditions: one using water (S/W) and the other using ethanol (S/E) as the reaction medium. The focus was placed on the composition of the aqueous phase, particularly the formation of volatile fatty acids (VFAs). Ethanol-assisted experiments consistently produced more alkaline process water (pH 7.6–8.2) compared to water-based runs. COD values in S/W samples ranged from 9358 mg/L to 19,756 mg/L, indicating significant organic loading. Hydrochar derived from the ethanol experiments exhibited higher energy content, with a peak high heating value (HHV) of 21.9 MJ/kg at 240 °C, compared to 19.9 MJ/kg in S/W samples. VFA concentrations were also enhanced under ethanothermal conditions, especially at lower temperatures: formic acid (30.4–34.8 mg/L), acetic acid (8.7–9.6 mg/L), and propionic acid (10.8–14.6 mg/L). These results demonstrate ethanol’s potential to enhance both the yield and quality of liquid and solid products in HTC of sewage sludge.

11 February 2026

Mass yield after sewage sludge and water (S/W) experiments and sewage sludge and ethanol (S/E) experiments.

The paper presents an experimental comparison between a standard evacuated tube solar collector and a collector featuring a modified internal manifold architecture with an integrated metal-foam heat-exchange chamber. Both collectors have an identical geometric volume of the heat-exchange region, ensuring that the measured differences in performance are exclusively attributable to changes in the internal design of the manifold. The experimental validation comprised five measurements conducted at two mass flow rate levels, 60 and 120 kg·h−1, under real outdoor operating conditions. The evaluation was based on time-resolved performance data and included instantaneous, cumulative, and dynamic indicators, such as energy yield, volumetric energy density, performance stability, dynamic sensitivity, and energy inertia. The results show that the solar collector with the modified manifold consistently achieves a higher energy yield, higher volumetric efficiency, and lower dynamic sensitivity than the standard collector. These benefits are obtained at the cost of increased pressure losses, indicating a trade-off between energy performance and hydraulic demand under real operating conditions.

11 February 2026

Comparison of Standard and Metal Foam-Enhanced Heat Pipe Manifold Designs and Flow Paths—The yellow annular region indicates the heat-exchange region.

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Phytochemicals
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Phytochemicals

Extraction, Optimization, Identification, Biological Activities, and Applications in the Food, Nutraceutical, and Pharmaceutical Industries
Editors: Ibrahim M. Abu-Reidah

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Processes - ISSN 2227-9717