Drying Unit Research Articles

MATHEMATICAL MODELLING OF DRYING PROCESS

The aim of this study is to experimentally investigate the drying kinetics of common basil using a solar drying unit. The tests consist in studying the effect of constant and variable drying air temperature on the drying kinetics. In this empirical approach, we aim to determine and compare drying characteristic curves under conditions where the drying air temperature is constant or variable. Subsequently, correlations describing the drying rate will be developed, these will be used at a later stage to size and model the solar dryer. Few numerical models have been used in the literature to explain the drying kinetics of common basil, in fact, given the complexity of the transport mechanisms and the diversity of products, a single model cannot represent all situations. This justifies an experimental study in the laboratory to determine the drying kinetics of a particular product.

A novel approach for the active‐mode indirect drying of food grains with high temperature thermal energy storage system

AbstractThis article introduces a novel approach for the active‐mode indirect drying of food grains using an independent high‐temperature thermal energy storage (TES) system. It uses commercial software to conduct numerical analysis of a solar drying unit fused with indirect TES. Employing commercial grade phase change material X‐180, solar drying unit incorporates scheffler dishes, receiver, TES, thermic fluid pump, air blower, and dryer fitted with a radiator. Heat transfer fluid Thermenol‐66 has been used to facilitate the heat transfer from receiver to TES and dryer. Two distinct TES designs, one without fins (case A) and the other with fins (case B), have been used to encapsulate phase change material and facilitate the flow of heat transfer fluid. The dynamic performance of independent solar drying unit components was examined at various mass flow rates during charging and discharging process. The results demonstrate that adding 42 fins, i.e. (case B), reduces the charging and discharging time to 22% and 24%, respectively. Due to high charging and discharging power, the rate of temperature change in case B is 19% higher compared to case A. To maintain drying quality, the dryer should have a continual flow of hot air at a constant temperature. Therefore, utilization of the TES, case A, provides a significantly higher uniformity index and a more extended drying period during the discharge process.

Raising the Drying Unit for Fruits and Vegetables Energy Efficiency by Application of Thermoelectric Heat Pump

Drying food stuffs and other materials belongs to one of the most commonly used feedstock processing techniques, featuring rather high energy consumption. The major disadvantage of conventional electric convective-type household dryers is substantial thermal energy emission into the environment with a wet exhaust, worked-out drying agent. Among other principal disadvantages common to all dryers of this type, the following have to be mentioned: spatial inhomogeneity of heating a product under processing and that of drying agent distribution due to its temperature reduction and relative humidity growth as it moves upwards. A block diagram and a breadboard model of a convective-type thermoelectric dryer employing a thermoelectric heat pump have been designed. In our approach, a product is treated with the help of a drying agent (normally, heated air) with partial exhaust-air recirculation and heat recovery. Laboratory studies of the drying process have been carried out using apple fruits as a test material in order to evaluate the power consumed for evaporation of 1 kg of water in the newly developed convective-type thermoelectric drying unit. Physical parameters of apple fruits before and after drying both in the thermoelectric drying unit and in a conventional series-produced convective-type domestic dryer have been reported. The energy efficiency of the newly designed drying unit has been compared with that of some series-produced samples. It has been found out that, unlike conventional convective-type dryers, the breadboard model of the developed thermoelectric drying unit features a smoother product drying process owing to the presence of side air channels and more effective drying agent path organization in the processing chamber. This conclusion was supported by the results of the carried out tests. Application of thermoelectric heat pumps with the function of the exhaust drying agent heat recovery will make it possible to reduce the drying agent heater installed capacity and the power consumed by the newly designed convective-type thermoelectric drying unit by up to 20% in the course of the drying process, compared to series-produced household convective-type dryers.

Application of a Surface Waveguide in Microwave Drying Units of the Agribusiness Industry

In the last two decades, the electromagnetic field of the microwave range has been successfully introduced into various branches of the agribusiness industry as one of the most promising and advanced technologies for drying manufactured products. In this regard, the article proposes a new microwave irradiation technique for drying various objects based on a surface waveguide’s properties. The paper analyses the main links that make up the surface waveguide as a microwave irradiation system and shows the ways of their implementation. The article describes the advantages of applying a vibratory device for exciting a surface wave, using a re-emitting antenna array, and operating a single conductor with a dielectric coating as a surface waveguide. Such advantages make it possible to introduce microwave drying units with the required distribution of electromagnetic field energy along the irradiated material, small dimensions, high drying quality, and low price.

Development of Innovative Yarn Drying Unit Using Triz Effects Database

Günümüzde yaratıcılık ve karmaşık problemlerin çözümü mühendislik tasarımında en çok aranan niteliklerdendir. Bilindiği üzere TRIZ sistematik yaratıcılık ve yenilikçilik için en etkili yöntem olarak tanımlanmaktadır. TRIZ’in araçlarından biri olan ideallik herhangi bir teknik sistemin çalışma ömrü boyunca basit, etkili ve güvenli olması gerektiğini ifade eder. Bu çalışmada ideal sonuca yakın, yenilikçi çözüm bulma yöntemlerinden olan bilimsel etkilerin, iplik üretiminde boya sonrasında “sabitlenmemiş boyanın” temizlenmesine yönelik olarak yıkanması sonrasında kurutma problemlerinin çözümü için nasıl kullanıldığı ve erişilen çözüm analiz edilmiştir. Kısaca bilimsel veri tabanları ve kullanım yönteminden bahsedildikten sonra, problem detaylı olarak tanıtılmıştır. Etkiler veri tabanı kullanımına yönelik öngörülen algoritmanın kullanılma süreci, önerilen bilimsel etkilerden kavramsal tasarıma geçiş ve daha sonrasında da prototip oluşturularak testlerinin yapılmasından bahsedilmiştir.

Технология инфракрасной сушки жидких материалов

The research was carried out in the field of infrared drying of liquid materials. The problems in this area have been studied and a solution in the form of an infrared installation has been proposed. A low-temperature film electric heater has been selected as a heating element, which has a low operating temperature, which helps to preserve useful substances in the final product, as well as reduce the development of pathogenic microflora. The problem of adhesion and burning during drying of liquid materials has been discovered. Several types of substrate made of different materials have been studied. Studies have been conducted to determine the radiation flux. The dependences of the flow density on time for different heater locations are compiled. The most optimal material for the substrate has been identified. An automatic control system for the drying plant has been developed. An infrared drying unit has been developed. Studies have been conducted on the drying of liquid materials at the proposed installation. The analysis of the obtained results is carried out.

Occupational hazard management in grain storage units

With the expansion of global grain production, in which Brazil ranks 4th with 7.8%, and, in light of the estimated production for the 2022/2023 harvest of 309.9 million tons, there is a deficit in storage capacity, currently representing 60.9% of production. Given the importance and expectation of expanding, it is necessary to prevent illnesses and accidents linked to this process. This work aims to develop an occupational hazards management model during the grain storage and drying processes, to determine the hazards that workers are exposed in their activities. The methodology was applied in western Paraná, Brazil, in a grain drying and storage unit during the inter-harvest and harvest periods to analyze, identify, evaluate, prioritize, and develop an action plan for the hazards. Among the hazards identified in the literature and at the site, exposure to heat and noise was evaluated, generating a score that represents the hazard situation in the environment. Of the 104 possible points in the evaluation, occupational exposure to heat obtained the lowest score of 70 (regular level), compared to noise with a score of 90 (normal level). For solving identified non-conformities, it can be highlight the replacement of thermal protection gloves and installation of a on-site temperature and humidity meter. With the methodology, it is possible to evaluate hazards and propose mechanisms that lead to their resolution, prioritizing the most critical levels according to the generated score.

USE OF THE WORKING BODY OF THE UNIVERSAL VIBRATORY MILL FOR DRYING GRAIN MATERIAL

One of the most perspective directions of intensification of heat and mass transfer in the processes of drying plant materials and increasing the energy efficiency of drying plants is the application of a vibration field for mixing grain material while moving in the drying chamber. The analysis of existing vibration installations has revealed that the most promising is the usage of vibratory grinding chambers with spatial circulation of material for the implementation of grain heat treatment, in particular drying. As a result, it is proposed to use the proven element base of a vibratory mill as a working body of which grinding chambers with spatial circulation of the load are used. The article presents the structural and technological scheme of a vibratory thermal drying unit, the structural parameters of the unit, and a mathematical description of the grain drying process. The obtained differential equations constitute a mathematical model of the nonstationary process of continuous drying of grain material and determine the change in time, parameters of grain and steam-gas mixture at the outlet of the grain drying chamber. The constructed mathematical model of the drying process makes it possible to determine the modes of heating and dehydration of grain material during circulation in a vibrating chamber with a conductive energy supply and partial vacuuming of the chamber, to expand the technological capabilities of the "vibrating mill" type installations. The graphical dependences of the temperature and moisture content of grain over time, the data for which were determined experimentally, are presented when a monolayer of grain of mass m is heated on a heating surface of area F at a stabilized surface temperature θn. In this work, the kinetics of drying and heating of grain were obtained, which were used to calculate the parameters of the vibrothermal drying unit. Also, using the results of the experiments, the performance indicators of the vibration dryer created on the basis of the grinding chamber of the vibrating mill were determined.

A comparison of the drying kinetics, energy consumption and colour quality of drying medicinal leaves in direct-solar dryer with different colours of collector cover

In some countries, Neem and Bitter leaves are often offered as dried medicinal leaves and one of the appealing aspects to consumers is that they retain their original colour after drying. Hence, the purpose of this study was to examine if collector cover colour variations can impact the quality and chlorophyll loss in solar-dried Neem and bitter leaves. To vary the colour spectrum, three distinct coloured polyethene materials with different colours were used as top window-cover for the dryer chamber and collector, which formed a single drying unit of a solar cabinet dryer. The results showed that the yellow-covered solar drying unit achieved 38.8% thermal efficiency, which declined by 1.43% and 10.41% for the blue and white-covered drying unit respectively. The yellow-cover dryer created higher internal temperature and drying rate, enabling it to dry the leaves faster. The average drying rate for Neem and bitter leaves was 0.003762–0.003849 kg/h, and 0.004348–0.004689 kg/h respectively. The specific energy consumption for drying the leaves ranged from 10.52 to 13.89 MJ/kg for all dryers. Colour analysis showed that the yellow-covered dryer dried bitter leaf near its natural colour, while the blue-covered dryer dried Neem near its natural colour. Lograthimic model predicted their moisture ratio better for drying the leaves.

Development of Web-based Smart Monitoring System using IoT & Mobile Application for Grapes Drying Unit

IoT (Internet of Things) is one of the leading technologies that is used in many fields and departments. This IoT technology has made the working of systems easier and more hassle-free. This IoT is having tremendous usage and application in the agricultural fields making farmers’ life easier. This IoT technology is used for automation in the agricultural fields to monitor various parameters in real time, helping the farmers in yielding good crops. One such smart system used to safeguard raisins from the climatic changes has been proposed in this research. The drying of grapes requires specific temperature and humidity to be maintained to attain good yield. There is always a possibility of sudden unexpected rains, and it would be difficult for the people to close the sheds of such large drying units and also it is a time-consuming process. In such cases, this model is used where the sheds automatically get closed with the help of the motors and input from the rainfall sensor. Also, additional features such as flame alarm and buzzer module, which help in detecting the fire and informing the farmer about the danger to take immediate action, are used. All these controlling and monitoring are done by making use of the IoT technology and the WSN.

WAYS OF IMPROVING THE DESIGN OF THE WALNUT CONVECTIVE DRYER

Walnuts belong to the products most exposed to the risk of oxidative deterioration at the stages of storage, transportation and sale. At the same time, it should be taken into account that specific botanical varieties grown in different geographical regions have an individual chemical composition that determines the intensity of the ongoing oxidation processes, therefore nuts of different batches have different potential for storage. The lack of a system of traceability of purchased nut batches at the stages of production, logistics and sale, as well as the lack of objective methods for assessing the potential level of preservation, which leads to the incorrect establishment of the expiration dates of walnuts, and as a result, more than 30% are sold in trade networks walnuts with signs of bitterness. The quality of nuts during storage depends mainly on the moisture content, storage temperature, relative humidity, oxygen content level, commercial type of nuts, packaging materials, storage form and type of technological processing of nuts (without shell, in shell, fried, etc.). Nuts are products of long-term storage. The purpose of the research is a comprehensive analysis of the operation of modern convective dryers of agricultural raw materials and the determination of ways to improve them to ensure high-quality and uniform drying. According to the results of the analysis of the existing drying units, their disadvantages and advantages were determined. The peculiarities of the application of hopper dryers in various production lines among industrial goods, food products, and construction materials that require mixing of bulk products are analyzed. The use of these dryers has shown high reliability in operation when drying significant volumes of raw materials, absence of stagnant zones, high efficiency of the process and automation of the entire technological process of drying. In order to intensify the process of convective drying, it is necessary to improve the heat and mass transfer both inside and outside the raw material, an increase in the drying temperature will inevitably lead to overheating of the product and loss of biologically useful substances, so one of the ways to increase the drying speed can be the use of mixing devices and devices , installed inside the drying chamber.

Drying Process Modeling and Quality Assessments Regarding an Innovative Seed Dryer

The dehydration of agricultural products is a topic of research covering the preservation and conservation of the quality of agricultural and food items. The actual tasks of environmental protection include creating novel solutions to reduce the energy needs and exothermic consequences of the bulk of industrial processes. Due to the fact that air temperature and velocity in the seed layer are not uniform, the currently employed seed dryers have significant energy requirements and generate a lot of heat. A device that addresses this problem was developed and is now the subject of a patent application. The Coandă effect-based tronconic plates used in the dryer enable warm air to be dispersed uniformly throughout the product mass. Mathematical modeling was used for the design, operation, and optimization of the baffled drying unit. The investigations, which were conducted by modifying and observing the operational parameters (the velocity and temperature of the warm air) used four distinct types of seed with three different beginning moisture concentrations. Following the completion of the CFD simulation, the unit’s design was created in SolidWorks. The seed and air humidity were measured using sensors, and the air speed was measured using an anemometer. The current lines and fields were used to express the speed and temperature results. The unit with deflectors reduced the amount of heat released by up to 15.38% and reduced the amount of energy used by up to 14%.

Research of optimum calculation of vibrating infrared dryers

The purpose of this study is to develop and improve the technological process and experimental and technical means of drying mulberry silkworm cocoons in an infrared (IR) drying unit, which can significantly speed up the processing and obtain a quality end product, as well as reduce energy costs for drying. The scientific novelty consists of the application of vibration in the process of drying silkworm cocoons by infrared radiation and the development of generalized calculation of such drying units. Our proposed calculation of infrared drying units is the most optimal calculation for silkworm cocoon morphing and drying.

Дослідження впливу основних режимних параметрів на ексергетичний ККД конвективної сушильної установки

Mathematical model is proposed for the numerical study of exergy losses in a chamber convective drying unit and the determination of the Impact of the main mode parameters during convective drying on the exergy coefficient of the useful effect of the convective drying unit. The mathematical model is implemented in the MathCad environment. The SKRR-400 intermittent chamber dryer for drying agricultural products with a one-time load of 400 kg was chosen as the object of the study. The components of exergy losses, which have the greatest influence on the thermodynamic perfection of the drying plant, are determined, and the ways of reducing their specific weight in the exergy balance are indicated. Numerical studies of the effect on the exergetic efficiency coefficient of the dryer of such parameters as the ambient temperature, the temperature of the coolant at the entrance to the drying installation, the temperature of the coolant at the outlet of the drying installation — spent coolant, the temperature of the steam condensate in the heater have been carried out. A numerical experiment showed that with the increase in the initial air temperature, the useful specific exergy consumption for moisture evaporation decreases and the change the prominence of the dryer performance does not affect the total exergy losses. It is established that the energy or exergetic and thermal efficiency factors of the dryer differ significantly . According to the calculations, the exergetic.efficiency of the chamber dryer, which reflects its thermodynamic perfection, does not exceed 14.5 %. Comparison of exergetic.efficiency with the energy or thermal efficiency of SKRR-400 type dryer showed that the thermal efficiency of dryers is significantly higher (50,4 % versus 14,5 %). It is hypothesized that this is due to the fact that thermal efficiency does not take into account the phenomena of irreversibility of heat and mass transfer processes. It was established that losses with waste coolant in the exergy balance make up 8 %, and in the thermal balance — 33,2 %. According to the results of the numerical experiment, it is shown that increasing the efficiency of drying units can be achieved by improving their heating devices and reducing their losses.

The methodological foundations of the thermal efficiency in a convective drying unit of the chamber type

The article deals with the issue of increasing the efficiency of the drying plant, gives theoretical prerequisites and analytical calculations and a generalized formula for determining thermal efficiency is derived. The author and the staff conducted a number of experiments on a pilot plant. According to the results of the experiments, curves of the dependence of the efficiency of the drying unit on the heating temperature of the chamber surface and at the outlet of the spent drying agent from the drying chamber were obtained. It has been proven that with an increase in the temperature of the spent drying agent, the thermal efficiency decreases. The optimum temperature of the discharge heat of the agent is considered. The expediency of using a heat-accumulating rubble nozzle was also justified, which allows saving up to 14% of the thermal energy required for the drying process.

Dynamic Limit Based Model Predictive Control of a Flash Drying Unit

A model predictive controller was implemented at the flash drying unit of the Anglo American Platinum Polokwane smelter. The controller uses a mix of standard model predictive control technology and dynamic control limits (based on the rate of change of the hot gas generator average bed temperature) to improve temperature stability across the unit. The improved temperature control resulted in the ability to process 1.80% more concentrate through the unit without the need to increase coal feed, as well as reducing the number of coal feeder trips that result from high temperature events.

Environmental Impact Assessment of a Solar Drying Unit for the Transformation of Food Waste into Animal Feed

Food waste valorization via its transformation into animal feed is a viable alternative for improving food security and the diversion of organic waste from landfills. The manuscript presents the environmental impact assessment of the construction and operation of a novel solar food waste drying unit on the island of Crete in Greece, which is treating food waste from hotels. Life cycle assessment is utilized for the impact assessment. The results indicate a total carbon footprint of approximately 217.5 kg CO2 eq. per ton of treated food waste. In conclusion, the operation phase is the major contributor to the environmental impacts, due to the utilization of electricity.

Performance study on forced convection mode V-trough solar air heater with thermal storage: An experimental approach

This paper presents the performance evaluation of Forced Convection V-Trough Solar Air Heater (FCVTSAH) with latent thermal energy storage unit. The FCVTSAH contains three pass solar air heater, an absorber unit reserved with paraffin wax, an air blower and the cylindrical drying unit. The thermodynamic performance is evaluated using the drying of agricultural commodities in the dry air temperature having the temperature in the range of 35 °C to 68 °C. The experimental test is carried out from 20th April 2020 to 22nd April 2020 at (12.96° N and 77.63°E). The energy and exergy performance analysis of each component is done using standard mathematical expression available from litrature. It is evaluated that the average energy efficiency is fluctuates from 2 % to 50.5 % and exergy efficiency fluctuates from 2.4 % to 25 %. The latent heat storage unit energy and exergy efficiency fluctuates from 20.3 % to 24.5 % and 8.9 % to 12.8 %. The drying unit exergy efficiency is in the range of 20.5 % to 74.3 % respectively.

Advanced exergoenvironmental analysis of the oil shale retorting process with SJ-type rectangular retort

A framework integrated the advanced exergy analysis with the theory of life cycle assessment is constructed to evaluate and optimize the environmental performance of energy conversion systems. The SJ-type oil shale retorting (SJ-OSR) process as one of the energy conversion systems with severe environmental pollution is employed to demonstrate the feasibility of the proposed approach. The results show that the avoidable exergy destruction of the retorting unit and recycle gas combustion unit to their total exergy destruction are 56.49% and 65.12%, respectively. The environmental impact for the total exergy destruction (BD,tot) of the SJ-OSR process is 1219.05 mPts/s. The environmental impact for total endogenous exergy destruction is 984.63 mPts/s, which accounts for 80.77% of the BD,tot. As for the drying, retorting and recycle gas combustion units, their environmental impacts related to avoidable exergy destruction rates are larger than the unavoidable parts. Most of the environmental impact with respect to the avoidable exergy destruction rates is endogenous (350.22 mPts/s). Based on the proposed two improvement strategies, ultimately, the BD,tot of the improved process decreases obviously from 1219.05 mPts/s to 1037.87 mPts/s, and the proportion of BD,tot reduced is about 14.86% of that for the existing process.

Techno-economic analysis and life cycle assessment of microwave co-pyrolysis of food waste and low-density polyethylene

This paper presents a techno-economic analysis (TEA) and life cycle assessment (LCA) of microwave (MW) co-pyrolysis of comingled food waste (FW). Lab scale (capacity- 1 kg/d) MW co-pyrolysis studies of FW and low-density polyethylene (LDPE) yielded 42 wt.% of bio-oil, 42 wt.% of biochar and 16 wt.% of pygas. The fixed and monthly operating cost of the lab scale MW co-pyrolysis reactor was 10,00,000 INR/kg and 8,248 INR/kg, respectively. The respective cost of a commercial MW co-pyrolysis plant (capacity-100 kg/d) was estimated as 53,12,585 INR/kg and 24,420 INR/kg. It was estimated that with 7 % of the internal rate of recovery (IRR), the breakeven point would be achieved within 4 years. The LCA of the commercial MW co-pyrolysis plant evaluated that the drying and pyrolysis unit consumed 91 % of total energy and contributed most to environmental impact. Thus, emission of 38.92 kg CO2 eq, 48.00*10-3 kg SO2 eq, 7.70*10-3 kg PO4-3 eq, 1100.10*10-3 kg dichlorobenzene (DCB) eq and 3.50*10-3 kg C2H6 was projected for MW co-pyrolysis of 100 kg FW and LDPE. Overall, TEA and LCA suggested that the commercial MAP plant would provide higher conversion efficiency, lower energy consumption (0.54 kWh/kg) and environmental risk with an attractive economic return by selling bio-oil + biochar at the rate of 40 INR/kg.