scholarly journals Effect of Solar Radiation on the Drying Parameters of Mint (Mentha Spicata L.) Dried in Natural Convective Solar Dryer

Author(s):  
SEBIHA REHMAN ◽  
SEEMIN RUBAB

Abstract The paper presents a kinetic study of solar dried mint (Mentha spicata L.) without any pre-treatment. Mint grows effortlessly in Kashmir valley but is not obtainable throughout the year because of inconsiderate weather conditions. The genus belongs to the Labiatae family and includes large varieties with different properties. A significant quality parameter is its colour. The drying kinetics of mint leaves dried in Domestic Solar Dryer in terms of colour attributes, moisture content, drying time, non enzymatic browning, water activity, rehydration ratio was studied. This study is very useful for household scale drying of mint leaves to optimize drying process and to achieve superior quality dried product at home maintaining its colour and aroma.

Author(s):  
Margarita Castillo-Téllez ◽  
Beatriz Castillo-Téllez ◽  
Luz María Hernández-Cruz ◽  
Gerardo Alberto Mejía-Pérez

The drying process is very intensive in energy consumption. Mexico is a major producer of food, especially of varieties of chilies, with quality culinary and medicinal properties. The 65% of the national market as a dry product, which gives a benefit. In the drying process, the convective technology was used, using a horizontal tunnel with direct solar heating air. The kinetics of the solar dryer with direct heating is possible, with an average drying time of 16 hours of solar irradiance. The tests were performed in Temixco, Morelos, Mexico, located at 18 º 51 'of LN and 99º 14' of LO, with average values of 850 W/m2 irradiance maximum. The chamber temperatures were in a range between 31 and 45 °C. The air velocity range was set between 1.3 and 2.4 m/s. Final moisture contents of the dried chili were obtained in a range between 8% and 6% h.b. with an average drying velocity of 4.7 humidity degree/h. The solar direct drying is a technology that allows recovering and trying different agricultural surpluses and could promote the establishment of agro-industries.


2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.


2021 ◽  
Vol 13 (1) ◽  
pp. 73-82
Author(s):  
Yubao Niu ◽  
Shiyu Wei ◽  
Huan Liu ◽  
Yongzhen Zang ◽  
Yuxue Cao ◽  
...  

The purpose of this research is to investigate the kinetics of nutrient quality (Vitamin C (Vc), reducing sugar and total acidity) change of winter jujube slices that under different drying temperatures (55, 60, 65 and 70?) and different air velocities (3, 6 and 9m/s) during the air-impingement drying process. Results showed that the content of Vc, reducing sugar and total acidity decreased with increasing drying time. Furthermore, analysis of variances indicated that the drying temperature, air velocity and time had a significant effect on the loss of Vc, reducing sugar and total acidity (p<0.05). Zero order, first order and Weibull models were used to fit the experimental data, Weibull model was considered as the most suitable one to the degradation kinetics of Vc, reducing sugar and total acidity in dried samples at different temperatures and air velocities. According to the Arrhenius formula, the activation energy of Vc, reducing sugar and total acidity degradation kinetics were 63.78 kJ/mol, 36.48 kJ/mol and 153.51 kJ/mol, respectively. This research can provide some references for enhancing dried products quality in the jujube drying industry.


Author(s):  
Chang Peng ◽  
Saeed Moghaddam

Abstract Over the past two decades, due to the rising energy prices and growing awareness about climate change, significant efforts have been devoted to reducing the energy consumption of various home appliances. However, the energy efficiency of clothes dryers has little improvement. Recent innovations in the direct-contact ultrasonic fabric drying technique offer new opportunities for energy saving. In this technique, high-frequency mechanical vibrations generated by the ultrasonic transducer are utilized to atomize water from a fabric in the liquid form, which demonstrates great potential for reducing energy use and drying time of the fabric drying process. Here, for the first time, fabric drying kinetics under different direct-contact ultrasonic drying conditions were investigated experimentally and analytically. The drying processes of four kinds of fabrics were experimentally tested under different ultrasonic transducer vibration frequency (115, 135, and 155 kHz) and input power (1.2, 2.5, and 4.4 W) conditions. According to the experimental data, five different kinds of models were applied to quantify the drying kinetics of fabrics during direct-contact ultrasonic drying. The models not only incorporated the transducer parameters but also the parameters related to the nature of fabric. Our evaluation results of model prediction performance demonstrated that the two empirical models, i.e., the Weibull model and the Gaussian model, were superior to the three semi-theoretical models for anticipating the drying kinetics of fabrics under direct-contact ultrasonic drying. Furthermore, the Weibull model is more suitable for practical energy-efficient direct-contact ultrasonic fabric drying applications compared with the Gaussian model.


Author(s):  
Fabiano An. Fernandes ◽  
Sueli Rodrigues

Abstract Genipap (Genipa americana L.) is an exotic tropical fruit that can be used in production of sweets, liqueurs, and several other foodstuffs. In this work the effect of ultrasonic pre-treatment prior to air-drying on dehydration of genipap was investigated. The study allowed estimating the water diffusivity in the air-drying process for genipaps submitted to ultrasound. Results showed that the water diffusivity increased after application of ultrasound and that the overall drying time was reduced by 28.2%. During the ultrasonic treatment, genipaps lost sugar showing that the ultrasonic pre-treatment can be a valuable process to produce dried fruits with lower sugar content.


2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Masnaji R. Nukulwar ◽  
Vinod B. Tungikar

Abstract The objective of this study is to find an optimized thin-layer mathematical model suitable for drying kinetics of turmeric. Turmeric has a high moisture content which necessitates effective drying. A 10 kg, sample batch, of turmeric was dried in a solar dryer. Drying air temperatures and air velocity were observed in the range of 55 °C–68 °C and 0.7 m/s–1.4 m/s, respectively, in the drying experiments. It is seen that the moisture content of the turmeric is reduced from 77% to 11.93% in 22 h when compared with open sun drying, which required 60 h for the same reduction in the moisture content. Scheffler dish was used to generate steam for the dryer. Seven thin-layer mathematical models, cited in the literature, had been used for the study. These models were applied for different trays placed in the dryer. The result of the research and experimentation showed that the Page model fits best for drying in the steam-based dryer and open sun drying. Experimental results showed 63.33% saving in drying time, and the drying efficiency was found as 29.85%. Uncertainty in the drying efficiency was observed as 0.67%. Experimental investigation and the findings from the mathematical modeling are presented in this paper.


Author(s):  
I. A. Shorstkii ◽  
D. A. Khudyakov

The transition to an efficient economy and efficient production requires building the foundations for the development of energy efficient technologies and the drying of biomaterials to convert them into useful products. The purpose of this work is to analyze the effectiveness of pretreatment with a pulsed electric field (PEF) in the process of convective drying of biomaterials. The PEF was processed with electric field strength of 2, 4 and 6 kV/cm, the number of pulses 500, with a pulse duration of 50 ?s. Based on the electrical conductivity data of the biomaterial, the index of the disintegration 56% was determined before and after the PEF treatment, which confirms the existence of an electroporation mechanism of the material structure. The drying process is presented with a description of various mathematical models. PEF pre-treatment with the parameters of electric field strength 4 and 6 kV / cm and the number of impulses 500 allowed to reduce the drying time by 13.8% for the value E = 0.02. Total time spent on the drying process reduced by 20-25 minutes. It should be noted that the total energy spent on PEF pre-treatment (<150 W / kg) compared with the energy spent on the drying process is incommensurably small. Statistical analysis of the considered mathematical models showed good convergence of most models with experimental data. The considered technology of pretreatment of PEF can ensure the effective processing of biomaterials in the required amount to obtain high-quality and safe products. Obtained data of the kinetics process can be used to the mathematical model of the drying process design with the use of preliminary treatment processing.


2020 ◽  
Vol 4 (1) ◽  
pp. 14-20
Author(s):  
Mietra Anggara ◽  
Silvia Firda Utami

Indonesia one of the plants that leaves and seeds grow has many useful benefits for human life, namely candlenut. The post-harvest handling of candlenut at the farm level it is generally still done traditionally where candlenut is drying on the floor or by direct exposure to solar radiation. They need approximately 7-9 days to get the appropriate drying results. Candlenut drying is influenced by the intensity of solar radiation on temperature and drying time according to the required hazelnut content. the dry hazelnut can use solar radiation power that is solar dryer. Absorbent plate is one component that is very important because it functions to absorb the intensity of solar radiation and convert it into heat energy and move it to the workpiece (candlenut) above it. In this study, testing was done on variations of the absorbent plates of zinc, aluminum and iron as well as variations in the thickness of the absorbent plates. Data collection starts at 09:00 until 15:00 WITA in sunny weather conditions. The results showed that the aluminum absorbent plate with a thickness of 0.04 mm was more effective and efficient in drying the candlenut to increase the productivity of the candlenut. The highest absorbent plate temperature and drying time were found on the aluminum absorbent plate with a thickness of 0.4 mm that is 72.36 oC and a drying time of 6 hours and meets the standard of moisture content of candlenut solution, which is 5.3%.  


Author(s):  
S. T. Antipov ◽  
V. V. Toroptsev ◽  
A. N. Martekha ◽  
A. A. Berestovoy ◽  
I. S. Yurova

The analysis of the influence of the main factors on the kinetics of the drying process of fermented wheat raw materials in a vibro-boiling layer is presented. The purpose of the study is to study the influence of the main technological parameters on the kinetics of the drying process of fermented wheat raw materials in a vibrating boiling overflowing layer at atmospheric pressure. The main factors affecting the drying process were selected: the temperature of the drying agent supplied to the dryer, the speed of the drying agent, the vibration amplitude of the gas distribution shelves, the vibration frequency of the gas distribution shelves. The influence of temperature and air velocity on the drying process of raw materials, the influence of the amplitude and frequency of oscillations of the gas distribution grid on the kinetics of the drying process of the fermented product, as well as the influence of the specific load of the product on the process of moisture removal are shown An analysis of the curves shows that with an increase in the amplitude of the oscillation, it reduces the drying time, and an increase in the frequency of oscillation of the shelves contributes to a decrease in the drying time. In this case, a uniform increase in the drying intensity is observed over the entire range of the amplitudes considered. An increase in the oscillation frequency of the gas distribution grid also helps to reduce the duration of the drying process of fermented wheat raw materials. It should be noted that the amplitude of the oscillations more strongly affects the decrease in the drying time of the raw material than the frequency Thus, we concluded that in the intervals under study the changes in the amplitude and frequency of vibrations of perforated shelves on the drying process of fermented wheat raw materials are more strongly affected by the amplitude of vibrations. In addition, when choosing vibration parameters, the specific load of the material on the grate and its initial humidity should be taken into account..


2019 ◽  
Vol 12 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Abdul Wasim Noori ◽  
Mohammad Jafar Royen ◽  
Juma Haydary

AbstractAn energy independent active indirect solar drying system for the study of food products drying at specific climate conditions was developed and tested. As a model material, sliced tomato was selected because of its short shelf live, high humidity and potential to be a high value dried product. Indirect solar dryer enabled complete protection of the dried material against sunlight, birds, insects, rain and dust during the drying process. The solar dryer system design includes a rectangular section (1000 × 600 × 400) mm chamber and a flat solar collector (1500 × 600 × 100) mm with the surface area of 0.9 m2. Air flow was induced by a fan installed at the inlet of the collector and powered by a photovoltaic solar panel and a battery system. Temperature and humidity of air were monitored at the collector inlet, collector outlet and the drying chamber outlet. The key element of the collector is a 10.5 m long rectangular section aluminum pipe (55 × 35) mm coated with an absorption layer. The maximum dryer capacity is around 3 kg of wet material (sliced tomato) per batch. Average air temperature increase in the collector was measured to be 30 °C during the winter season. Air relative humidity decreased from 21 % to 15 % after passing through the collector. The moisture of tomato slices decreased from the initial value of 92 % down to 22 % during the time of the experiment (30 h). Quality of tomatoes dried using the designed solar dryer differed significantly in color as well as in texture from those dried by the commonly used methods, like an open sun drying system. Equilibrium moisture content of the product was reached after 30 h in December when the maximum outside temperature was 17.6 °C. The tomato mass decreased from 333 g to 33.15 g; the mass loss being approximately 90 %. The heated air temperature and humidity at the dryer inlet and outlet were influenced by the change of the ambient temperature and humidity during the day. Variation of the drying rate with the change of the ambient temperature and humidity was observed. During summer, when the sun radiation increases, the drying time for sliced tomato with 9 mm thickness decreased from 25 h to 15 h. The sample thickness also has an impact on the drying process. When the sample thickness increased from 9 mm to 12 mm, the drying time increased from 15 h to 20 h of active device time.


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