Tray Dryer Research Articles

Development and assessment of generalized drying kinetics in multi-tray solar cabinet dryer

This work evaluates the feasibility and determines a generalized drying characteristic curve in an indirect mode multi-tray solar cabinet dryer. The study considers a combination of tray reordering pattern and dryer performance index (DPI) method to map the influence of four primary factors, which influence the drying kinetics into a generalized curve. Three levels of each of the four factors, such as the mass flow rate (0.03–0.05 kg/s), heat input (500–1000 W/m2), loading density (1.0–2.5 kg/m2), and flake thickness (2–8 mm), represent twelve different drying kinetic curves. Therefore, the DPI value corresponding to the generalized curve would directly indicate the dryer performance and reduce the complexity in assessing the agro-product samples' drying behaviour in multiple trays. This study was initially validated, and it highlighted the merits of a tray reordering pattern in achieving drying uniformity per batch. Dimensionless drying process time (τ), a function of drying constant (k) and drying time (t), resulted in a maximum percentage deviation of 27.93% among the twelve drying kinetic curves. In contrast, expressing the moisture ratio as a function of DPI and drying process time (τ) reduced the maximum percentage deviation to 2.33%, with the value of correlation coefficient (r) above 0.972 for all the twelve drying kinetic curves. These consolidated findings pointed out that the adopted tray reordering pattern greatly influences the DPI method’s success in establishing a generalized curve in a multi-tray dryer.

Surface Analysis, Mechanical and Corrosion Behavior of Welded Steel in 1M HCl Corrosive Media with Epoxy/Alumina Coating

Asparagus roots were dried in four selected driers vacuum, fluidized bed, tray, and solar dryer at temperatures starting from 40 to 70 °C. The drying kinetics of asparagus roots was studied with the analysis of the influence of all stated drying conditions on the drying rate, dehydration ratio, rehydration characteristic, color characteristics, and energy consumption. With an increase in the temperature required for drying asparagus, there is an increasing trend of dehydration ratio (DR) and decreasing trend of drying time. The rehydration characteristics are found to be increases with a decrease in drying temperature from 70-60 °C but decrease with a further decrease in drying temperature from 60-40 °C. The energy consumption based on the drying conditions showed great thermal sensitivity and was found higher for low-temperature drying. The results of color characteristics (Chroma, hue angle, and ΔE) showed that the cream color of roots was relatively unaffected by drying. However, the brightness of roots was observed to be increased. Eleven thin-layered drying mathematical models were applied to experimental data of different drying conditions, and the model best describing its behavior was selected based on the coefficient of determination (R2), sum square error (SSE), and root mean square error (RMSE). All selected models give good fitting results (R2 > 0.96) and found the cubic model as the most suitable model for all treatments (R2 > 0.99).

Experimental studies on natural convection open and closed solar drying using external reflector

For low temperature agricultural crop and meat drying, dryers utilizing the renewable energy source (solar energy) appear to be an efficient technique as it is ecofriendly, energy efficient, and available in free of cost. This work presents the experimental investigation on a solar food dryer equipped with external reflectors to enhance the rate of drying efficiency by removing the moisture content available in the anchovy fish. A comparison of conventional open solar drying is carried out to assess the parameters such as drying efficiency, moisture removal rate, and heat energy required for drying the anchovy fish using the modified solar dryer using the natural convection technique. From the experimental results it is observed that the relative humidity greatly influence the rate of drying. The average relative humidity during the experiments using open solar drying is found as 50-65% whereas, the using solar dryer the average relative humidity inside the chamber is found as 20-35%. The relative humidity of the fish using open solar drying is higher as compared to solar dryer drying as the drying products are kept in open atmosphere. The physical examination results on the dried products proved that using a modified solar dryers, the dried product is free from insects, and dust. Also, it is found that the loss of color from the product is a minimum while compared to conventional open solar drying. The results showed that the thermal efficiency of top tray (dryer 1) and bottom tray (dryer 2) is comparatively higher as compared to that of conventional open solar drying and found as 16.73 and 19.34 %, respectively. Results also showed that nearly 20.05% of the energy could be saved using the modified solar dryer as compared to the open solar drying technique.

Standardisation of cooking and conditioning methods for preparation of quick cooking germinated brown rice

Quick cooking germinated brown rice (QCGBR) is a novel convenient food product with valuable health benefits. Different cooking and conditioning methods were studied for standardisation of its preparation process. Freshly harvested paddy of Prativa variety was milled in rubber roll sheller to get brown rice which was soaked in demineralised water at 30 ​± ​2 ​°C for 12 ​h followed by 24 ​h of germination in an incubator maintained at 27 ​± ​1 ​°C temperature and 85–90% relative humidity to obtain germinated brown rice. The germinated brown rice was immediately cooked using three different cooking methods such as atmospheric cooking at normal ambient pressure, pressure cooking with water in a domestic pressure cooker at 1 ​bar gauge pressure and pressure steaming (without water) with steam at 1 ​bar gauge pressure to predetermined cooking time. The cooked samples after washing were then conditioned by keeping them at 4 ​°C for 24 ​h (refrigerated storage) or −10 ​°C for 24 ​h (frozen storage) in a house hold refrigerator. The stored samples were taken out after 24 ​h and tempered for 1 ​h followed by drying in a tray dryer at 90 ​°C to obtain the quick cooking germinated brown rice. The samples obtained from different cooking and conditioning methods were analysed for cooking quality, physico-chemical parameters, damaged grain percentage, GABA content and sensory attributes to standardise the cooking and conditioning methods. Cooking time, water uptake ratio, solid loss and volume expansion ratio of quick cooking germinated brown rice varied significantly with cooking and conditioning methods of its preparation (p ​< ​0.05). Though frozen conditioning resulted in lowest cooking time, it was not accepted by the sensory panel due to high damaged grain percentage, distorted shape and softness after cooking. The QCGBR obtained by pressure cooking method followed by refrigerated conditioning resulted in highest sensory score.

Development of Organic Briquettes from Slaughterhouse Waste as Nutrient Source for Plant Growth

A study was conducted to develop organic briquettes using biomass originating from slaughterhouse wastes and to investigate its potential as a nutrient source for plant growth. Dried rumen contents were mixed with fresh blood collected after bleeding of animals in different proportions and dried using tray drier. The dried rumen content-blood (RB) mixture was further mixed with commercially available coir pith in 12 different proportions. The rumen content-blood-coir pith (RBC) mixture was formed into briquettes using a hydraulic biomass briquetting machine. Each organic briquette was 5 cm in diameter and had an average weight of 30–40 g. The treatments were analyzed for pH, moisture content, electrical conductivity (EC), organic carbon (OC), total nitrogen, carbon: nitrogen ratio, total phosphorus and total potassium. Organic briquette having rumen content with 100% blood and 80% coir pith (T10) recorded the highest total nitrogen, total phosphorus and total potassium content. The treatments for plant growth studies were selected based on the criteria that each treatment had highest values for at least two of the three primary nutrients of nitrogen, phosphorus and potassium. The treatments T5, T7, T8, T10 and T12 were selected for plant growth studies. Pot experiment using selected briquettes was carried out to determine the effect of selected briquettes on growth parameters and yield attributes of okra (Abelmoschus esculentus). Nutrient release pattern of the selected organic briquettes was also studied. The best desirable growth parameters and yield attributes of okra was observed in T10. Availability of nutrients in the medium were relatively less during first 2 months of planting (MAP), however, it significantly increased between 3 and 4 MAP, which resulted in better plant growth and fruit yield. The study showed that there is great potential for development of organic briquettes using slaughter house wastes as an eco-friendly process, which are compact, easy to transport and market, and ideal for grow bag cultivation and garden nurseries.Graphic Abstract

The Effects of Thermal Pre-treatment on the Production of Banana Chips using Solar Tray Dryer

Gıda ürünlerinin uzun süre muhafaza edilmesi için doğrudan güneş ışınımı altında kurutulması durumunda özellikle ürünün renginde bozulma ve besin değerlerinde azalma meydana gelmektedir. Bu sebeple, güneşin etkisinden dolaylı faydalanılabilen güneş enerjili kurutucular kullanılmaktadır. Bu çalışmada, termal ön işlem uygulanmış ve uygulanmamış muz halkaları güneş enerjili raflı kurutucuda kurutulmuştur. Halka halinde kesilmiş muz önce belirli sıcaklıkta bulunan su, şeker ve sitrik asit çözeltilerinden birine daldırılmış daha sonra güneş enerjili kurutucuda kurutulmuştur. Kurutma koşulları, ön işlem, çözelti türü ve güneş enerjili kurutucuda kalma süresi olarak belirlenmiştir. Kurutma koşullarının nem kaybı, çapsal büzülme oranı ve renk parametrelerine etkisi belirlenmiştir. Muz halkalarının kurutulmasında en uygun daldırma çözeltisi&#x0D; sitrik asit çözeltisi olarak belirlenmiştir. Sitrik asit çözeltisine daldırılan muz halkaları güneş enerjili raflı kurutucunun yanı sıra güneş altında ve gölgede kurutulmuştur. Muz halkalarının kurutulması üzerine raflı güneş enerjili kurutucuda kurutulmadan önce termal ön işlem uygulanmasının olumlu etkisi olduğu belirlenmiştir. Muz halkalarının batırıldığı çözelti türü ve kurutucuda kalma süresinin artmasıyla ile hem çapsal büzülme oranı hem de nem kaybı artmıştır.

Performance evaluation and economic analysis of modified solar dryer with thermal energy storage for drying of blood fruit ( Haematocarpus validus )

In the present work, a modified solar dryer (MSD) assembled with a solar collector consisting of phase change material (PCM)—thermal storage unit has been designed and the dryer performance investigated while drying blood fruit. The proposed design of MSD with double-glazed glass on a solar collector increased the drying air temperature by 15%–18%. The mean temperature in the drying chamber of MSD was 60°C with 10–12 hr of the continuous drying period. The Midilli model was well suitable to explain the drying kinetics of the blood fruit in MSD. The quality parameters like color, TPC, TFC, and antioxidant activity of dried slices were compared with fresh samples. Simulated model behaviors were similar to experimental values with an RMSE and RMSE% remaining below 1.2°C and 0.86%, respectively. Environmental impact analysis of MSD showed that the energy payback and cost payback periods were estimated as 1.23 and 2.16 years, respectively. Practical application A proposed modified solar dryer with thermal energy storage was designed and investigated for drying of blood fruit. The energy storage unit in the MSD increases the drying time by 19%, effective at off-sunshine hour and retains the quality of dried products as well as improves the drying rate compared to tray dryer. The exergy analysis, energy payback period, CO2 emission, and cost payback period are performed for MSD and found to be better than tray dryer (TD). The MSD's energy payback time is 1.23 years, and the calculated CO2 reduction is 4.14 tons in 5 years, 9.64 tons in 10 years, and 20.65 tons in 20 years, respectively. The solar dryer that has been built will be ideal for marginal farmers and small scale entrepreneurs and can be extended to any capacity.

Effect of treatment and drying method (Solar and convective) on physico-chemical quality of dried moringa leaves

Moringa is one of the promising crop high nutritional and therapeutic values. While drying of moringa leaves, there is significant loss in physical, chemical and nutritional composition of leaves. So, the present study was conducted to investigate the effect of different treatment and drying method (solar and convective) on physico-chemical quality of moringa leaves. Moringa leaves that were sorted, washed and surface dried were considered non-treated whereas leaves that were blanched at 7.5 min after sorting were considered treated. The following samples were dried in three dryers viz., PAU advanced domestic solar dryer, PAU domestic solar dryer and convective tray dryer. Samples that were treated had better physico-chemical quality than untreated sample. Similarly, samples dried in PAU advanced domestic solar dryer had better quality retention i.e. had low moisture content, low colour change, higher protein content, higher ascorbic acid and higher total antioxidant activity.

The Effect of Tilt Angle of Axial Fan Blades on Air Flow Distribution in the Cabinet Dryer: Simulation Study Using Computational Fluid Dynamics

The application of tray dryer is widely used for various commodity dryers due to its simple construction. However, one of the drawbacks of tray dryer is the uneven airflow distribution in the drying chamber which results in the drying rate in the tray position being unequal. As a result, the degree of dryness of the product also varies. This study investigated the effect of fan blade angle on airflow distribution in the dryer cabin through numerical simulations. The axial fan diameter was 350 mm with a thickness of 20 mm. The variations of axial fan blades used were 10o, 20o, 30o and 45o. The number of blades used was 4, and the allowable airflow limit was 2 m x 1 m x 1 m, with an axial fan rotation of 500rpm. Based on the simulation results, the 45o fan angle had good air distribution results compared to the 10o, 20o, and 30o fan angles. Likewise, the distribution of air produced by the fan was evenly distributed, because the greater the angle of the fan used for the dryer, the better the results would be obtained.

Drying of lithium-ion battery negative electrode coating: Estimation of transport parameters

Drying of the coated slurry using N-Methyl-2-Pyrrolidone as the solvent during the fabrication process of the negative electrode of a lithium-ion battery was studied in this work. Three different drying temperatures, i.e., 70˚C, 80˚C and 90˚C were considered. The drying experiments were carried out in a laboratory tray dryer at atmospheric pressure. Mass transfer coefficient and effective capillary diffusivity of the solvent during drying were estimated. A semi-empirical model was developed to estimate the parameters. In addition, different thin-layer empirical models were fitted to the experimental data, and the parameters were estimated using the best-fitted model. During the drying process, shrinking of the coating was considered while estimating the parameters.

A Short Review on Fluidized Bed Dryer

This artical also discusses about demostration of fluidized bed dryer with principle and application and other processing. This has lead to development of thechnology, process and equipments which not only reduce time but also increasing the output. A Fluidized bed dryer significantely reduce drying time, compared with vaccum dryer or tray dryer. In the pharmacutical industry, fluidized bed dryer are typically used for pellets drying, coating and granulation. Fluidized bed drying are very well known to yield high heat and mass transfer and hence adopted to many industrial drying process particularly pharmacy product. In this paper we show construction, working of the fluidized bed dryer. It work on the drying principle. It has several advantages and disadvantages.

Effects of different drying methods and ascorbic acid pretreatment on carotenoids and polyphenols of papaya fruit in Ethiopia.

Frequent consumption of fruits can prevent nutrient deficiencies and promote health. However, the perishability and unaffordability of fruits had led to very low levels of fruit consumption in low‐ and middle‐income countries (LMICs). The objective of this study was to evaluate the retention of nutrients and bioactive compounds of papaya fruit (Carica papaya L) with/without ascorbic acid pretreatment and drying under different techniques, to then estimate the vitamin A intakes for vulnerable population. Yellow pulp ripped papaya fruits (i.e., >75% level of skin color/stage level 4) (n = 14), with and without ascorbic acid pretreatment were dried using (a) solar drying: open‐air, tray driers, and glasshouse; (b) refractance window drying; (c) oven drying; and (d) freeze‐drying (control). The fresh fruit had high moisture content (87%) and an acidic pH. The dried papaya had a water activity of 0.5–0.6. The highest TPC, TFC, total carotenoids, and ß‐carotene were found in freeze‐dried papaya samples, followed by refractance window, and solar glass house (p < .05). The highest retention in total carotenoids (81.5%) and ß‐carotene (61.9%) relative to freeze‐drying was for the refractance‐window; 25 g of dried papaya could contribute to 38% of the retinol equivalents’ requirement for young children. Ascorbic acid pretreatment increased the retention of total carotenoids, ß‐carotene, TPC, and TFC (p < .05) by (6–11)%, (8–34)%, (7–58)%, and (6–30)%, respectively, for all the drying methods. Refractance window and solar glass house drying can improve diets and constitute a promising food systems’ intervention that can increase year‐round availability, accessibility, and affordability of vitamin A‐rich fruits like papaya.

Effect of the drying process on the color change, fissure development, and morphology of fortified rice kernels

AbstractFortified rice kernels (FRK) were manufactured using extrusion technology and dried in a hot air tray dryer. The present study was aimed to find the effect of air temperature (40, 50, 60, and 70°C) and the drying time (0–160 min) at 1.0 m/s air velocity on color attributes of FRK. The increase in temperature and time decreased the L* and WI and increased the a*, b*, and ΔE values of FRK. The kinetic modeling suggested a fairly good fitting of the quadratic model for ΔE and WI. The Page model (R2 ≥ 0.9512, RMSE ≤ 0.0556, and χ2 ≤ 0.0037), as an alternate approach, showed the best fitting to predict the color change ratio of FRK. For fissure and morphological analysis, the FRK were dried to a final moisture content of 12–13 %wb at each drying temperature. The results revealed that the drying at 50–70°C formed fissure inside the FRK and was confirmed by the X‐ray CT scan images. However, the scanning electron microscope (SEM) image analysis did not show any fissure at the surface of FRK. Thus, the lower temperature (40°C and 120 min) drying resulted in better color attributes with no fissure inside the FRK.Practical applicationsFRK are being used to blend in the normal rice in the 1:100 ratio to prepare micronutrient fortified rice. It is expected that the FRK should be indistinguishable in normal rice after blending. Color is an important parameter that could make easy detection of FRK in normal rice. This makes it necessary to match the characteristics of FRK with normal rice in terms of color, physical dimensions, and density. Moreover, fissure formation in FRK leads to disintegration during cooking. Therefore, the study's findings will help to get an idea about the color change during the commercial drying of FRK and decide the drying conditions that will not develop fissure inside the FRK.

The Application of a Data Acquisition System and Airflow Control System in an Air Dehumidified Drying Machine

There are various possible drying methods used in seed drying. The tray dryer with an air dehumidifying system was used to produce various agricultural seeds. Seed drying by using an optimal air temperature requirement with low relative humidity can accelerate the drying process. To meet the specific drying requirement for agricultural products, air dehumidifying process, measurement data record, and airflow control were conducted in the drying machine. The objective of this research was to apply the data acquisition system and airflow control for seeds drying. The drying machine consisted of an air dehumidifying unit, data acquisition and airflow control unit, and a tray dryer unit. The air dehumidifying system was used to minimize the moisture in the drying air. The data acquisition system was used to monitor temperature and relative humidity distribution along with the drying machine. While the airflow control system was used to confirm that the requirement of air dehumidifying process was reached. A tray dryer used dehumidified air as the air input for the seed drying process. The drying machine was successfully reaching the optimal condition for drying with the temperature and relative humidity distribution were recorded. The optimal condition for the seed drying was reached by using this air dehumidified drying machine.

Mathematical modelling of hot air drying of water chestnut kernels

Drying characteristics of water chestnut kernels were evaluated at different air temperatures (50, 60 and 70 °C) in commercially available hot air tray dryer and sun drying. Drying rate of water chestnut kernels 1.1880, 1.6181, 2.6688 and 0.7249 g water/ g dry matter-min were found at drying temperatures of 50, 60, 70 ºC and sun drying (38 ± 5 ºC), respectively at 15 min time interval. The Midilli–Kucuk model fitted better on the basis of higher R2 value (0.99978) and lower values of X2 and RSME values as 0.0000162 and 0.004028784 at 60 °C.

Anamur muz halkalarının osmo-solar kuruma davranışının belirlenmesi için yanıt yüzey yönteminin kullanılması

Aims: In this study, banana rings were dried by a solar tray dryer together with osmotic dehydration called osmosolar dehydration. It was aimed to predict osmosolar dehydration drying conditions by Response Surface Method (RSM).Methods and Results: Banana rings were firstly immersed in sucrose solution and then dried in a solar dryer. Inputs as drying conditions were chosen as solution concentrations, slice thickness, immerse time and solar drying time. Also, outputs are chosen as water loss, shrinkage ratio and yellow color change. The results clearly showed that both water loss and shrinkage ratio have increased due to increased solar drying time and immerse time.Conclusions: The correlation coefficient (R2) values of the water loss, shrinkage ratio and yellow color change for the RSM model were respectively found as 0.979, 0.930 and 0.920.Significance and Impact of the Study: Anamur Banana, which has high moisture content and drying temperature, was dried using a combination of osmotic dehydration and solar drying. Pretreatment of osmotic dehydration was found to be effective in dried banana rings with solar tray dryer.

Microwave and Ultrasound Pre-Treatments for Drying of the "Rocha" Pear: Impact on Phytochemical Parameters, Color Changes and Drying Kinetics.

The objective of this research was to evaluate the effect of drying temperature and innovative pre-treatments (i.e., microwave and ultrasound) on “Rocha” pear drying behavior and quality characteristics, such as color, total phenolic content and antioxidant activity. Experiments were carried out with pear slabs subjected to microwaves (2450 MHz, 539 W, 4 min, microwave oven) and ultrasounds (35 kHz, 10 min, in an ultrasonic bath) as well as control samples. The drying process was conducted in a tray dryer at three different temperatures (50, 55 and 60 °C) and a fixed air velocity of 0.75 m/s. Microwave technology resulted in a higher quality deterioration in dried pear samples compared to those of controls and ultrasound pre-treated samples. The combined application of ultrasound pre-treatment and the higher drying temperature of 60 °C was characterized by the lowest color changes (ΔE = 3.86 ± 0.23) and higher preservation of nutritional parameters (total phenolic content, TPC = 345.60 ± 8.99; and antioxidant activity, EC50 = 8.80 ± 0.34). The drying characteristics of pear fruits were also analyzed by taking into account empirical models, with the Page model presenting the best prediction of the drying behavior. In conclusion, ultrasound application is a promising technology to obtain healthy/nutritious dried “Rocha” pear snacks as dietary sources for consumers.

Studies on variations in Physico-chemical Properties of Mustard Seeds during Drying and Fluidized bed Drying Kinetics

Proper drying methods can prevent the damage of food grains by changing in physic-chemical properties and minimize the spoilage during storage and improve the nutrition quality of grain. Thus proper drying methods are very important to choose based on operating conditions and cost. In present work, the typical variations in physico-chemical properties of mustard seeds obtained from Varshakonda Village in Telangana State were investigated during drying in Hot Air Oven, Tray Drier and Fluidized Bed drier. Removal of moisture during fluidized bed drying is observed very effective. Also, nutritional properties like fat, protein, phosphorous &amp; iron contents were found to decrease considerably low during drying in Fluidized bed comparatively in hot air oven and tray drier. Therefore, mustard seeds can effectively dried in Fluidized Bed. The fluidization characteristics of mustard seeds under different operating conditions were investigated in order to find out best drying method to dry mustard seeds.

Farklı ön işlemlerin atıştırmalık nar çerezi üretimine etkileri

Objective: In this research, the production and quality characteristics of new healthy pomegranate snacks (Punica granatum L.) obtained by drying after different pre-treatments were investigated. Material and Methods: Besides control group, three different pre-treatments were applied to the pomegranate seeds before drying. Pomegranate seeds without any pre-treatment were grouped as “control” samples (C) and other group was boiled in 80 °C water for 2 minutes “boiled” (B). Samples treated with sucrose and glucose (60 °Brix) solutions (18 hours at 40 °C) for osmotic dehydration were grouped as "sucrose” (S) and “glucose" (G) group. Samples in all groups were dried at 65 °C in a tray dryer at an air velocity of 1.6 m/s until the moisture content reached 6%. Results: According to physical and chemical analysis results, the total sugar content was between 87.96-97.50 g/100 g; the amount of invert sugar 46.23-62.75 g/100 g; the total amount of phenolic substance 255.6-407.6 mg/100 g; antioxidant capacity values ranged from 40.2% to 49.6%. Total loss of phenolic substance according to raw material was found to be the lowest in boiled samples. According to sensory tests in terms of all sensory properties (color, texture, flavour and preference), boiling pre-treatment applied sample was determined as the most preferred sample. Conclusion: When all results are analysed, to obtain a healthy snack product using pomegranate fruit, it is thought that applying the boiling pre-treatment before drying to the pomegranate may be appropriate for preserving nutrients and obtaining a preferred snack pomegranate.

Effect of inulin concentration on physicochemical properties and antioxidant activity of date powders obtained by hot-air tray dryer

In the present study, it was aimed to produce free-flowing date powders using various levels of inulin as drying-aid agent (10, 20, 30, 40, and 50%) through hot-air drying at 60°C for 24 h. Effects of different inulin ratios on physicochemical properties of date powders were investigated. This is the first report which evaluated the suitability of this prebiotic carbohydrate as drying-aid agent to fabricate date powders. Inulin addition yielded date powders with high flowability. On the other hand, contents of bioactive compounds including total phenolics, flavonoids, and condensed tannins of date powders decreased significantly (P&amp;lt;0.05) as the inulin concentration increased from 10% to 50% Accordingly, DPPH-radical inhibition capacities reduced in date powders containing higher levels of inulin. Furthermore, significant correlations were detected between bioactives contents and antioxidant activity of date samples. The results showed that free-flowing date powders with improved prebiotic content may be produced by incorporating inulin up to ratio of 50% and used as sugar substitute in different food products.