Search Results (32)

This research examines the feasibility of recovering and recycling condensate water, a waste byproduct generated by Atlas Copco ZR315 FF industrial air compressors utilizing oil-free rotary screw technology with integrated dryers. Given the growing severity of global water scarcity, finding alternative water sources is essential for sustainable industrial practices. This study specifically evaluates the potential of capturing and treating compressed air condensate as a viable method for water recovery. The investigation analyzes both the quantity and quality of condensate water produced by the ZR315 FF unit. It contrasts this recovery approach with traditional water production methods, such as desalination and atmospheric water generation (AWG) via dehumidification. The findings demonstrate that recovering condensate water from industrial air compressors is a cost-effective and energy-efficient substitute for conventional water production, especially in water-stressed areas like Morocco. The results show a significant opportunity to reduce industrial water usage and provide a sustainable source of process water. This research therefore supports the application of circular economy principles in industrial water management and offers practical solutions for overcoming water scarcity challenges within manufacturing environments. Full article

Rotary dryers are widely used in industry for their ease of operation in processing large volumes of material continuously despite persistent challenges in energy efficiency, cost-effectiveness, and safety. Addressing the need for effective operator training, the purpose of this study is to develop virtual reality (VR) environments for industrial rotary dryers. Visual and behavioral aspects were considered in the methodology for developing the environments for two application cases—ammonium nitrate and low-rank coal drying. Visual aspects considered include the industrial-scale geometry and detailed components of the rotary dryer, while behavioral aspects were governed by mathematical modeling of heat and mass transfer phenomena. The case studies of ammonium nitrate and low-rank coal were selected due to their industrial relevance and contrasting drying characteristics, ensuring the versatility and applicability of the developed VR environments. The main contribution of this work is the embedding of validated mathematical models—expressed as ordinary differential equations—into these environments. The numerical integration of these models provides key process variables, such as solid temperature and moisture content along the rotary dryer, thereby enhancing the behavioral realism of the developed VR environments. Full article

Precise control and monitoring systems are essential for efficient energy consumption in food dehydration. This study develops an applied cyber-physical control system to optimize food dehydration in rotary dryers, integrating fuzzy control algorithms through data acquisition. The system architecture utilizes DHT22 transducers for temperature monitoring, a DHT11 for humidity measurement, an IP65 anemometer for dryer wind speed detection, and a load cell weight tracking system, all connected to an Arduino Mega 2560 R3 microcontroller implementing the integrated fuzzy logic library. Experimental evaluations were performed with different carrot loads (1.5, 2.5, and 3.5 kg), demonstrating optimal performance at the initial load of 3.5 kg with an energy consumption of 11,589 kJ for 9.33 h, achieving a final moisture reduction of 10%. The 1.5 kg sample showed optimal dehydration kinetics at an average dryer hot air velocity of 1.5 m/s, while maximum efficiency (86%) was achieved with the 3.5 kg load, compared to 30% and 17% for the smaller batches. These results validate the integration of cyber-physical systems to optimize the dehydration rate (0.301 kg/h), thereby ensuring product quality in agro-industrial drying applications. Full article

While traditional disposal of solid waste from the global wine industry causes significant environmental burden and hazards, a range of value-added by-products can be produced from the grape marc. This review focuses therefore on crucial sustainability-enhancing technologies for pomace dewatering and separation, which constitute a mandatory stage in obtaining storage-stable by-products and final value-added commodities. A number of dryers and separators were considered for pre-treatment of wet grape marc and analysed in terms of their design characteristics, functionality, feasibility, throughput and efficiency. A multi-criteria decision analysis was carried out to compare, rank and select the equipment which is most suitable for the purpose. It was found out that the rotary drum dryer and the drum screen separator with internal blade rotor are the best candidates to fulfil the technology requirements, while the flowsheet that includes an initial separation followed by drying of the resulting fractions is a rather attractive option. Valorising grape waste worldwide contributes substantially to achieving the United Nations Sustainable Development Goals for responsible consumption and production, mitigating climate change, caring for health and well-being, preserving land life and combating hunger. Full article

This study develops a value-added processing technique for grade-out cape gooseberry (Physalis peruviana Linn.) by applying mild hydrostatic osmotic pretreatment combined with rotary tray drying. Fruits classified as grade-out, often discarded due to aesthetic flaws, were subjected to osmotic treatment at 0.5 bar for 12 h using a sucrose solution enhanced with citric acid and glycerin. Pretreatment significantly elevated water loss (52.61%) and solid gain (18.12%), reducing moisture content prior to drying. Rotary tray drying was conducted at temperatures of 50, 60, and 70 °C. Drying at 60 °C achieved the ideal balance between efficiency and product quality. Samples pretreated and dried at 60 °C exhibited a 35% reduction in drying time while preserving superior color (ΔE = 13.54 ± 1.81), vitamin C (71.76 ± 2.57 mg/100 g dry matter, DM), total phenolic content (202.9 ± 10.91 mg GAE/100 g DM), and antioxidant activity (ABTS = 95.87 ± 3.41 µmol TE/g DM; DPPH = 89.97 ± 1.27 µmol TE/g DM). A production trial was conducted using 1500 kg of raw material from the Mae Hae Royal Project Development Center in Chiang Mai, Thailand. This process yielded 220 kg of high-quality dried fruit at an overall cost of USD 6.93 per kg. Local farmers successfully applied this technique, demonstrating its potential to enhance livelihoods, avoid postharvest losses, and valorize low-quality produce in line with Sustainable Development Goal 12. This supports the Royal Project Foundation’s vision for sustainable agriculture. Full article

This study evaluated the impact of different drying methods on the physicochemical, microbiological, and sensory qualities of coffees produced in the Campos das Vertentes (CV) and Alta Mogiana (AM) regions of Brazil. The sun-drying (S), sun-drying combined with rotary mechanical dryer (SM), and CoffeeDryer^® mechanical dryer (C) methods were compared at different harvest times for the same crop (2024). The results indicated that CoffeeDryer^® preserved relatively high levels of phenolic compounds and antioxidant activity, reaching 3.24 g of gallic acid equivalents per 100 g (g EAG·100 g⁻¹) and 47.96% antioxidant protection in the coffees produced in Alta Mogiana, whereas the sun-dried coffees presented relatively low values (2.20 g EAG·100 g⁻¹ and 28.96% protection). In the Campos das Vertentes region, C maintained 2.78 g EAG·100 g⁻¹ phenolic compounds and 50.29% antioxidant protection, outperforming combined drying (2.48 g EAG·100 g⁻¹ and 41.17%). Regardless of the region and time of harvest, the coffees dried by C had a water activity of less than 0.6 and more stable moisture content (7.73–10.42%), reducing the possibility of proliferation of filamentous fungi and, consequently, mycotoxins. In the sensory evaluation, CoffeeDryer^® guaranteed higher scores for fragrance/aroma and flavor, allowing the coffees to reach 80 to 81 points on the SCA scale, which is classified as special. Thus, the use of CoffeeDryer^® proved to be an efficient alternative for optimizing coffee drying, preserving its chemical and microbiological qualities, and enhancing its commercial and sensory value. Full article

The drying process is widely used in the food industry for its ability to remove water, provide microbial stability, and reduce spoilage reactions, as well as storage and transportation costs. In particular, rotary drum drying becomes important when it is applied to liquid and pasty foods because of the desire to maintain defined characteristics in terms of product moisture. This drying process is characterized by the existence of many linearities; therefore, different strategies for controlling this process have been proposed. This work focuses on the design of a hybrid PI–fuzzy control scheme for the rotary drum drying process; the idea is to use the advantages of fuzzy logic to obtain a robust monitoring and control system. A pilot plant rotary drum dryer was used to tune the PI control part. Then, the proposed scheme was programmed and tested at the simulation level, comparing it with a classical PI control algorithm. Full article

The growing demand for innovative solutions to accurately measure variables in dewatering processes has driven the development of advanced technologies. This study focuses on the evaluation of a measurement system in a rotary dryer used to dehydrate carrots at an operating temperature of 70 °C. The system uses the Arduino platform, strain gauges, and LM35 temperature sensors. Experimental tests were designed to evaluate the performance of the dryer, using initial quantities of carrots of 1.5 kg, 1.0 kg, and 0.5 kg. The novelty of this study lies in the application of fuzzy logic for signal conditioning in real time, in order to improve the precision of measurements, designed in MATLAB (version 9.5) and programmed in Arduino. The dryer reduces the water content of the product to a final average of 10%. The research offers a novel solution for the integration of an intelligent measurement system that optimizes dewatering efficiency. The manuscript is organized as follows: in the methodology section, the design of the measurement system is described; subsequently, the experimental results and the analysis of the dryer efficiency are presented, and finally, in the conclusions, the implications of the system and its possible applications in other processes are discussed. Full article

Energy consumption in the drying industry has made drying an energy-intensive operation. In this study, the drying time, quality properties (color, shrinkage, water activity and rehydration ratio), specific energy consumption (S.E.C), thermal, energy and exergy efficiency of corn drying using a hybrid dryer convective-infrared-rotary (CV-IR-D) were analyzed. In addition, the energy parameters and exergy efficiency of corn were predicted using the artificial neural network (ANN) technique. The experiments were conducted at three rotary rotation speeds of 4, 8 and 12 rpm, drying temperatures of 45, 55 and 65 °C, and infrared power of 0.25, 0.5 and 0.75 kW. By increasing drying temperature, infrared power and rotary rotation speed, the drying time, S.E.C and water activity decreased while the D_eff, energy, thermal and exergy efficiency increased. In addition, the highest values of rehydration ratio and redness (a*) and the lowest values of shrinkage, brightness (L*), yellowness (b*) and color changes (ΔE) were obtained at an infrared power of 0.5 kW, air temperature of 55 °C and rotation speed of 8 rpm. The range of changes in S.E.C, energy, thermal and exergy efficiency during the corn drying process was 5.05–28.15 MJ/kg, 3.26–29.29%, 5.5–32.33% and 21.22–55.35%. The prediction results using ANNs showed that the R for the drying time, S.E.C, thermal, energy and exergy data were 0.9938, 0.9906, 0.9965, 0.9874 and 0.9893, respectively, indicating a successful prediction. Full article

Convective drying is one of the most commonly employed preservation techniques for food. However, the use of high temperatures and extended drying times often leads to a reduction in product quality and increased energy consumption. To address these issues, hybrid processes combining convective drying with more efficient methods are frequently employed. This study investigates the convective rotary drying of carrot (cv. Nantes), assisted by microwaves and ultrasound, using a hybrid rotary dryer. In total, four distinct drying programs—comprising one convective and three hybrid approaches—were evaluated. The study assessed drying kinetics, energy consumption, and product quality. The use of ultrasound increased the drying rate by 13%, microwaves by 112%, and microwaves and ultrasound together by 140%. The use of microwaves reduced energy consumption by 30%, whereas ultrasound resulted in a slight increase. All processes resulted in a significant reduction in water activity. Ultrasound decreased the color difference index, while microwaves increased it compared to convective drying. Full article

The studies carried out address an important problem for the concrete and asphalt industry, referring to the wear phenomena that affect the elements (flights) of rotary dryers used to dry mineral aggregates. In this article, the authors propose a lifetime estimation method for rotary dryer flights. In order to benefit from greater credibility, the proposed method was applied based on the experimental results obtained, by the authors, in the laboratory, on a stand that reproduces a portion of the real equipment. Starting from these results, the authors identified the mathematical functions used to model the failure rates (wear) of the flights by referring to characteristic quantities for wear evaluation: mass loss of material; reduction in the thickness of the part; surface affected by wear. The experimental data—the input data for the proposed algorithm—correspond to six steels used in industrial applications. The wear phenomenon was modeled considering both the situation of uniform wear and the situation of differentiated wear on the flight surface. Therefore, the steel type with the highest service life values could be identified, namely, steel grades E and G. The method proposed in this paper can be extended to any category of material or part provided that the failure rate function is identified beforehand, possibly based on a laboratory experiment. Full article

The coffee fruit is preferably harvested at the cherry stage, with high moisture and metabolic activity, and must then undergo a drying process for better preservation of the bean and its sensory attributes. In this context, this study aimed to characterize the final quality of the Arara cultivar Arabica coffee processed using the wet method and subjected to six drying methods: three conducted at the agro-industrial establishment (fixed-bed dryer, rotary drum dryer, and combined drying) and three laboratory-scale methods (convective oven, cast-tape drying, and suspended terrace). Drying was carried out to reduce the coffee’s moisture content from an initial value of 46.2% on a wet basis (w.b.) to a final average value of 11.35% (w.b.). The fruits of in natura demucilaged coffee and the processed dry coffee beans were characterized for moisture, ash content, nitrogen compounds, lipids, total titratable acidity, organic acids, sugars, and the instrumental color of the beans. The sensory profile of the Arabica coffee was evaluated by five coffee specialists using the methodology proposed by the Specialty Coffee Association (SCA), and all the coffees were classified as a specialty. Full article

An experimental study and dimensional analysis of the effective heat transfer coefficient in a continuous-indirect rotatube dryer using forest biomass as the granular material isare developed in the present work. The study employed a factorial design $3^3$ to investigate the effects of feed flow frequency (20–35–50 (Hz)), drum rotational velocity (6–8–10 (rpm)), and saturated vapor pressure (4–5–6 (bar)) on the heat transfer coefficient. During steady state conditions, the moisture content profiles and inlet and outlet temperatures were measured within the experimental region, and parameters, such as the effective heat transfer coefficient, solid retention change, and moisture content ratio were studied. The results showed that heat transfer was optimized with high solid feeding rates, low pressure, and low rotation, with solid feeding being the predominant factor. The moisture content profiles revealed a change in the hydrodynamic behavior, with the center point of the experimental region being the least optimal. The dimensional analysis yielded a Nu number as a function of Pe, Fr, and the feeding dimensionless number. A new dimensionless energy efficiency number improved the coefficient correlation from 85.88 (%) to 94.46 (%), indicating the developed model potential to predict dimensionless variables and scale continuous-indirect rotatube dryers. Full article

Conventional flighted rotary drums usually have flights parallel to the rotating axis, which cannot facilitate the axial motion of the materials in the drum. Here, a new type of horizontal rotary drum with inclined flights and beads was designed. Inclined flights are used to facilitate the axial movement of beads and material, while beads are used as fillers to increase the gas-liquid contact area and to crush the solid materials. We simulated the drum and studied the axial motion of fillers using the discrete element method (DEM). To improve the mass and heat transfer performance, we optimized the distribution of beads in the active phase. The effects of the rotational speed, joint angle, and inlet flow rate in the drum were investigated systematically. The individual effects were evaluated in terms of the mass of particles in the active phase (MAP) and passive phase (MPP), the percentage of the active phase occupied by the particles (OAR), and the axial speed (AS). The response surface methodology (RSM) was used to investigate the significant effects of the interaction between the parameters. The maximum MAP value can be obtained by the following parameters: a rotational speed of 37 rpm, joint angle of 139°, and inlet flow rate of 7.83 kg/s. The interaction between rotational speed and inlet flow rate is the most significant for MAP. The joint angle and inlet flow rate have a significant interactive effect on AS. Besides, the rotational speed, joint angle and inlet flow rate show an interactive effect on OAR and AS. Based on the optimization results, the effect of the inclined angle on the axial motion of beads was also evaluated. The axial motion of the beads occurs mainly in the active phase. Compared to the drum without inclined flights, the drum with inclined flights has an enhanced axial speed increased by 26%. This study will be helpful for the design and optimization of drums with inclined flights. Full article

Rotary drum dryers operating in co-current mode are commonly used for drying food and feed in leaf form, reducing the damage caused by the high air temperatures typical of these dryers, as well as providing advantages including reduced drying times and increased energy efficiency. However, drying control to ensure a desirable product exit moisture content is strongly based on empirical practices, which are usually jealously guarded by producers and users, grounded in simplified mathematical modelling. To overcome these uncertainties, in this work, a more complete mathematical modelling approach, based on the solution of ordinary differential equations (ODEs), is developed. The ODEs describe the drying process in the drum dryer, where the air is continuously cooled and humidified as the product dries. The mathematical model developed was experimentally verified in a drum dryer by drying alfalfa, and the maximum relative error was found to be only 2.4%. Finally, a comparison between the complete model proposed here and a simplified model was conducted, using both for drying control to keep the product exit moisture content constant (i.e., at 0.111). The results indicated that the simplified model provided values of air inlet temperatures erroneously higher, up to +8.2%, with a consequent higher energy consumption, lower dried alfalfa quality, and a greater risk of fire, given that the product exit temperature was dangerously increased. Full article