Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

A scaled-up process for paddy drying was developed using hot air (HA) combined with radio frequency (RF) heating. The study was conducted using hot air (control treatment) arranged in descending order in four temperature levels, namely 80 °C at moisture content of 25–26%, 70 °C at moisture content of 20–25%, 60 °C at moisture content of 17–20%, and 50 °C at moisture content of 13–17%, as well as with hot air combined with radio frequency (HA/RF) at different paddy temperatures (45–60 °C) by adjusting the appropriate RF energy when passing through RF heating chamber, namely HA/RF45, HA/RF50, HA/RF55, and HA/RF60. Each treatment was performed in three replicates and data were statistically analyzed in a randomized complete block design. The quality attributes of paddies affected by the drying process were assessed: fissure percentage, color, milling quality, and sensory evaluation. The drying efficiency showed that the drying time and the specific energy consumption could be decreased by up to 54.44% and 23.17% at HA/RF60 and HA/RF45, respectively. As the RF heating temperature increased, the fissure percentage of brown rice kernels at HA/RF45 and HA was not significantly impacted. Regarding color evaluation, combining RF heating and convective drying at all given conditions could be statistically applied in terms of the b*, WI, and ΔE* value. Considering the milling yield of HA as the baseline, head rice yield was maximized at HA/RF45, while bran yield reached the maximum at HA/RF60. The liking score of cooked rice after it was dried using the HA method was the highest. This study concludes that the HA/RF45 was the most appropriate drying condition, and this may provide preliminary exposure to the industrial drying of paddies.

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Energetic and exergetic analysis of a convective drier: A case study of potato drying process

Open Agriculture ◽

10.1515/opag-2020-0058 ◽

2020 ◽

Vol 5 (1) ◽

pp. 563-572

Author(s):

Iman Golpour ◽

Mohammad Kaveh ◽

Reza Amiri Chayjan ◽

Raquel P. F. Guiné

Keyword(s):

Energy Consumption ◽

Research Work ◽

Specific Energy Consumption ◽

Exergy Efficiency ◽

Operating Conditions ◽

Energy Utilization ◽

Convective Drying ◽

Drying Time ◽

Energy And Exergy ◽

Exergy Losses

AbstractThis research work focused on the evaluation of energy and exergy in the convective drying of potato slices. Experiments were conducted at four air temperatures (40, 50, 60 and 70°C) and three air velocities (0.5, 1.0 and 1.5 m/s) in a convective dryer, with circulating heated air. Freshly harvested potatoes with initial moisture content (MC) of 79.9% wet basis were used in this research. The influence of temperature and air velocity was investigated in terms of energy and exergy (energy utilization [EU], energy utilization ratio [EUR], exergy losses and exergy efficiency). The calculations for energy and exergy were based on the first and second laws of thermodynamics. Results indicated that EU, EUR and exergy losses decreased along drying time, while exergy efficiency increased. The specific energy consumption (SEC) varied from 1.94 × 105 to 3.14 × 105 kJ/kg. The exergy loss varied in the range of 0.006 to 0.036 kJ/s and the maximum exergy efficiency obtained was 85.85% at 70°C and 0.5 m/s, while minimum exergy efficiency was 57.07% at 40°C and 1.5 m/s. Moreover, the values of exergetic improvement potential (IP) rate changed between 0.0016 and 0.0046 kJ/s and the highest value occurred for drying at 70°C and 1.5 m/s, whereas the lowest value was for 70°C and 0.5 m/s. As a result, this knowledge will allow the optimization of convective dryers, when operating for the drying of this food product or others, as well as choosing the most appropriate operating conditions that cause the reduction of energy consumption, irreversibilities and losses in the industrial convective drying processes.

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Comparative Study of Hot Air Drying and Microwave Drying for Dewatered Sludge

10.21203/rs.3.rs-178542/v1 ◽

2021 ◽

Author(s):

Wittawat Wulyapash ◽

Awassada Phongphiphat ◽

Sirintornthep Towprayoon

Keyword(s):

Microwave Power ◽

Specific Energy Consumption ◽

Microwave Drying ◽

Drying Methods ◽

Drying Time ◽

Hot Air ◽

Air Temperatures ◽

Dewatered Sludge ◽

Dried Sludge ◽

Seafood Processing

Abstract Large amounts of sludge are generated from wastewater treatment in seafood processing industries. Most of the dewatered sludge in Thailand is not utilized and disposed by landfilling. The dried sludge utilization as refuse-derived fuel (RDF) is an alternative solution due to the gross calorific value (GCV), which is greater than 21.9 MJ/kg. However, the key obstacle is its high moisture content of 87.4% (wet basis). Therefore, drying methods using hot air and microwave techniques were investigated for preparing dried sludge. The effects of hot air temperatures (100-150 °C) and microwave power levels (100-800 W) were compared on drying kinetics, specific energy consumption (SEC), and characteristics of the dried products. The results showed that drying times were decreased by increasing the hot air temperatures. In the same way, the increase in microwave power levels decreased the drying time. The application of microwaves contributed to reducing the drying time by more than 46% compared to the hot air. The reduction of drying times resulted in the saving SEC. The GCV of the dried sludge decreased with the decrease in the volatile matter (VM) due to the high component of VM as 79.5-80.3% (dry ash-free basis). The sludge dried by the microwaves showed a lower GCV than the hot air products. However, dried sludges still had high GCV (≥ 20.8 MJ/kg). Furthermore, the minimal variation of the product characteristics demonstrated that the microwave technique could be applied as an alternative drying method with a rapid process compared to the conventional hot air technique.

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Influence of Different Hot Air Drying Temperatures on Drying Kinetics, Shrinkage, and Colour of Persimmon Slices

Foods ◽

10.3390/foods9010101 ◽

2020 ◽

Vol 9 (1) ◽

pp. 101 ◽

Cited By ~ 2

Author(s):

Senadeera ◽

Adiletta ◽

Önal ◽

Di Matteo ◽

Russo

Keyword(s):

Moisture Content ◽

Quadratic Model ◽

Drying Process ◽

Air Velocity ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Drying Characteristics ◽

Drying Temperature ◽

Hot Air

Drying characteristics of persimmon, cv. “Rojo Brillante”, slabs were experimentally determined in a hot air convective drier at drying temperatures of 45, 50, 55, 60, and 65 °C at a fixed air velocity of 2.3 m/s. It was observed that the drying temperature affected the drying time, shrinkage, and colour. Four empirical mathematical models namely, Enderson and Pabis, Page, Logarithmic, and Two term, were evaluated in order to deeply understand the drying process (moisture ratio). The Page model described the best representation of the experimental drying data at all investigated temperatures (45, 50, 55, 60, 65 °C). According to the evaluation of the shrinkage models, the Quadratic model provided the best representation of the volumetric shrinkage of persimmons as a function of moisture content. Overall, higher drying temperature (65 °C) improved the colour retention of dried persimmon slabs.

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BIOFUELS DRYING PROCESS EFFICIENCY RESEARCH / BIOKURO DŽIOVINIMO PROCESO EFEKTYVUMO TYRIMAI

Mokslas - Lietuvos ateitis ◽

10.3846/mla.2013.99 ◽

2013 ◽

Vol 5 (6) ◽

pp. 609-614

Author(s):

Osvaldas Šlepikas ◽

Audrius Čereška

Keyword(s):

Positive Impact ◽

Ultrasonic Transducer ◽

Process Efficiency ◽

Convective Drying ◽

Drying Process ◽

Wood Pellets ◽

Drying Time ◽

Hot Air ◽

Special Stand ◽

Experimental Rig

The paper deals with biofuel drying process efficiency opportunities.Research was carried out with a special stand and performingexperiments. Experimental rig consists of an ultrasonic generator,ultrasonic transducer, a drying chamber and the humidity,temperature gauge. Tests were used for wood pellets. During theexperiment, they were irrigated with water, dried with hot air andadditionally exposed to different frequency ultrasonic vibrations.The tests results have showed that the convective drying processis combined with the ultrasonic vibrations, the drying time isreduced, which means a positive impact on the ultrasonic process.Studies have confirmed that the effectiveness of convectivedrying method combined with operating ultrasonic vibrationsincreases. Santrauka Straipsnyje nagrinėjamos biokuro džiovinimo proceso efektyvumo didinimo galimybės. Tyrimams atlikti sukurtas specialus stendas ir sudaryta eksperimento atlikimo metodika. Eksperimentinį stendą sudaro ultragarsinis generatorius, ultragarsinis keitiklis, džiovinimo kamera ir drėgmės, temperatūros matuokliai. Buvo tiriamos medžio granulės. Eksperimento metu jos buvo drėkinamos vandeniu, džiovinamos karštu oru ir papildomai veikiamos skirtingo dažnio ultragarsiniais virpesiais. Atlikus bandymus, rezultatai parodė, kad, veikiant konvekcinio džiovinimo procesą ultragarsiniais virpesiais, džiovinimo laikas sutrumpėja. Tai reiškia teigiamą ultragarso poveikį procesui. Tyrimais patvirtintas konvekcinio džiovinimo metodo efektyvumo, papildomai veikiant ultragarsiniais virpesiais, padidėjimas.

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Artificial Neural Network Approach for Impingement Drying of Germinated Brown Rice Soaking with Turmeric Solution

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.372.463 ◽

2013 ◽

Vol 372 ◽

pp. 463-466

Author(s):

Kiattisak Suntaro ◽

Khwanruedi Sangchum ◽

Supawan Tirawanichakul ◽

Yutthana Tirawanichakul

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Moisture Content ◽

Brown Rice ◽

Measured Data ◽

Drying Kinetics ◽

Drying Time ◽

Rice Samples ◽

Artificial Neural ◽

Drying Conditions

The objectives of this research are to determine the evolution of moisture transfer for germinated Thai jasmine Khao Dawk Mali 105 (KDML105) brown rice variety using impingement drying by eight commonly empirical drying modeling and artificial neural network (ANN) method. The experiments were carried out with drying temperatures of 80-100°C, initial moisture content of KDML105 rice samples soaking with turmeric solution was of 54-55% dry-basis and the desired final moisture content for each drying conditions was fixed at 14-16% dry-basis. The air flow rate was fixed at 7.0 m/s. The measured data in each drying conditions were simulated for getting drying equation by non-linear regression analysis. The results showed that the rice soaking with herb turmeric solution had no effect to drying kinetics and the simulated data using empirical drying equation of Henderson model had the best fitting to all measured data (R2of 0.9978-0.9995 and RMSE of 0.0001441-0.000414). For applying ANN modeling approach, the drying temperature and drying time were considered as the input variables for the topology of neural network while the moisture ratio was the output layer. The simulation results concluded that the simulated values of the ANN model, which was not concerned with any complicated physical properties of grain rice kernels, could be used for prediction drying kinetics and was relatively high accuracy compared to those predicted results of empirical models. So the ANN method without any complicated properties related of rice samples can approach for good prediction their drying kinetics as well as the complicated drying simulations method.

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Energy efficiency and physical integrity of maize grains subjected to continuous and intermittent drying

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v25n10p710-716 ◽

2021 ◽

Vol 25 (10) ◽

pp. 710-716

Author(s):

Geraldo A. Mabasso ◽

Valdiney C. Siqueira ◽

Wellytton D. Quequeto ◽

Rodrigo A. Jordan ◽

Elton A. S. Martins ◽

...

Keyword(s):

Energy Efficiency ◽

Moisture Content ◽

Energy Demand ◽

Air Flow ◽

Specific Energy Consumption ◽

Fixed Bed ◽

Membrane Integrity ◽

Drying Time ◽

Cell Membrane Integrity ◽

Tempering Time

ABSTRACT Grain drying is a common process, due to its need for the maintenance of quality, but it is the activity with the highest energy demand among the postharvest stages. Thus, this study aimed to evaluate the effect of different tempering times on the energy efficiency of drying process and maintenance of cell membrane integrity of maize grains harvested with moisture content at 0.34 ± 0.01 d.b. The grains were dried in an experimental fixed-bed dryer with control of temperature and air flow conditions. The experiment was conducted in a completely randomized design with five tempering times (0, 4, 8, 12 and 16 hours) and four repetitions, where zero corresponds to continuous drying, while the remaining times correspond to the intermittent dryings. The grains were dried at the temperature of 100 ºC and air flow of 15.4 m3 min-1 t-1 until reaching moisture content of 0.16 ± 0.03 d.b. For intermittent drying, the process was interrupted with 0.22 ± 0.02 d.b. and restarted after the tempering time. The increase of tempering time led to reductions in effective drying time, specific energy consumption, electrical conductivity and damage and increase in the drying rate and overall energy efficiency. Intermittent drying reduced the drying time, being 30.25% more efficient than continuous drying.

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Physico-chemical aspects of Thai fermented fish viscera, Tai-Pla, curry powder processed by hot air drying and hybrid microwave-infrared drying

PLoS ONE ◽

10.1371/journal.pone.0253834 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0253834

Author(s):

Warongporn Choopan ◽

Worawan Panpipat ◽

Mudtorlep Nisoa ◽

Ling-Zhi Cheong ◽

Manat Chaijan

Keyword(s):

Specific Energy Consumption ◽

Infrared Heating ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Fermented Fish ◽

Infrared Drying ◽

Hot Air ◽

Physico Chemical ◽

Fish Viscera

The objective of this research was to comparatively investigate the effect of hot air drying (HA) and hybrid microwave-infrared drying (MI) on physico-chemical characteristics of Thai fermented fish viscera, Tai-Pla, curry powder (TCP). HA was carried out at 60°C, 70°C, and 80°C and MI was carried out at a microwave power of 740, 780, and 810 W with a constant infrared heating power (500 W) for different drying times to obtain the final moisture content ≤ 12.0% and the water activity (aw) ≤ 0.6. The quality characteristics of TCP were governed by HA temperature and MI output power. TCP dried using HA and MI at all conditions had similar contents of protein, lipid, ash, fiber, and carbohydrate (p>0.05). The fastest drying rate was detected when MI at 810 W for 40 min was applied (p<0.05). In this condition, TCP had the lowest browning index (A294 and A420) and the highest lightness (L* value) (p<0.05). TCP dried with MI at all powers had higher phenolic content and lower TBARS compared to HA (p<0.05). However, no significant differences in DPPH• scavenging activity were observed among TPC made by HA and MI (p>0.05). Similar Fourier transform infrared (FTIR) spectra with different peak intensities were observed in all samples, indicating the same functional groups with different contents were found. The bulk density of all TCP ranged from 0.51 g/mL to 0.61 g/mL and the wettability ranged from 24.02% to 26.70%. MI at 810 W for 40 min effectively reduced the drying time (5-fold faster) and lowered the specific energy consumption (18-fold lower) compared to the HA at 60°C for 210 min. Therefore, MI is a promising drying technique to reduce the drying time and improve the overall quality of TCP.

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Effect of pretrature with ultrasound in convention drying kinetics of bananas (musa paradisiaca)

Respuestas ◽

10.22463/0122820x.2820 ◽

2020 ◽

Vol 25 (3) ◽

Author(s):

Yesenia Campo-Vera ◽

Mauricio Eduardo Contreras ◽

Sandra Liliana Flórez ◽

Lucero Villamizar

Keyword(s):

Negative Impact ◽

Effective Diffusivity ◽

Green Technology ◽

Drying Kinetics ◽

Added Value ◽

Convective Drying ◽

Control Treatment ◽

Drying Time ◽

Musa Paradisiaca ◽

The Us

The use of ultrasound in food processing has increased in the last decade due to the reduction in times, temperatures, microbial and enzymatic inactivation, extraction of components of great interest to different industries; without altering or modifying its nutritional or organoleptic value during the transformation processes of raw materials into products with added value. Considering itself, a green technology by not causing a negative impact on the environment. In this work, the effect of US pretreatment (40KHz/130W/30°C /10, 20 and 30 min) on convective drying at 60°C / 2m / s of banana (musa paradisiaca) was evaluated. A diffusion model was used to describe the drying kinetics and to quantify the influence of the US on the effective diffusivity of water. Observing that the US significantly increased (p> 0.05) the drying speed in all the samples treated with an average reduction of 31% in the drying time with respect to the control treatment; reaching a weight loss of 77% with respect to the initial weight (3.8 to 0.9 g.). The exponential model is the most adequate to predict the experimental curves of banana drying and showed that the application of US increased both the effective diffusivity and the mass transfer coefficient, as corroborated by the values of the explained variance of 98.5 a 99.3%.

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Characteristics of commercial-scale radio-frequency/ vacuum (RF/V) drying for hardwood lumber

BioResources ◽

10.15376/biores.14.3.6923-6935 ◽

2019 ◽

Vol 14 (3) ◽

pp. 6923-6935

Author(s):

Honghai Liu ◽

Jingwen Zhang ◽

Wenjing Jiang ◽

Yingchun Cai

Keyword(s):

Radio Frequency ◽

Energy Conversion Efficiency ◽

Rf Heating ◽

Drying Time ◽

Drying Characteristics ◽

Commercial Scale ◽

Hardwood Lumber ◽

Conventional Kiln Drying ◽

Schedule Modification ◽

Calculated Amount

Two runs of commercial-scale radio-frequency/vacuum (RF/V) drying for maple hardwood were performed to explore the practical technology and its drying characteristics. The results revealed that the power density was a prerequisite for the drying schedule development. The drying time and in-process moisture content (MC) were evaluated by the calculated amount of dehydration at 1% MC removal. The drying defects, such as checks, bowing, and twist, and MC variation met the requirements of GB/T 6491 (2012). The drying rate of run 2 increased 22% after the drying schedule modification. The dehydration capacity was affected by the temperature, which first increased fast as the wood temperature increased to the boiling point and then increased more slowly after that point. The dehydration capacity was also associated with the initial lumber MC. Approximately 30% of the total energy maintained the chamber vacuum and approximately 70% was used for RF heating for both runs. The overall specific energy for water removal during RF/V drying had a competitive advantage compared with conventional kiln drying. The energy conversion efficiency of both runs was low at 50% during the warming stage, and increased to 80% and 90% for Run 1 and Run 2, respectively, during the drying stage.

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Evaluation of Infrared Radiation Combined with Hot Air Convection for Energy-Efficient Drying of Biomass

Energies ◽

10.3390/en12142818 ◽

2019 ◽

Vol 12 (14) ◽

pp. 2818 ◽

Cited By ~ 3

Author(s):

Hany S. EL-Mesery ◽

Abd El-Fatah Abomohra ◽

Chan-Ung Kang ◽

Ji-Kwang Cheon ◽

Bikram Basak ◽

...

Keyword(s):

Specific Energy Consumption ◽

Cost Effective ◽

High Water ◽

Convective Drying ◽

High Water Content ◽

Air Velocity ◽

Direct Combustion ◽

Hot Air ◽

Air Convection ◽

Drying System

Cost-effective biomass drying is a key challenge for energy recovery from biomass by direct combustion, gasification, and pyrolysis. The aim of the present study was to optimize the process of biomass drying using hot air convection (HA), infrared (IR), and combined drying systems (IR-HA). The specific energy consumption (SEC) decreased significantly by increasing the drying temperature using convective drying, but higher air velocities increased the SEC. Similarly, increasing air velocity in the infrared dryer resulted in a significant increase in SEC. The lowest SEC was recorded at 7.8 MJ/kg at an air velocity of 0.5 m/s and an IR intensity of 0.30 W/cm2, while a maximum SEC (20.7 MJ/kg) was observed at 1.0 m/s and 0.15 W/cm2. However, a significant reduction in the SEC was noticed in the combined drying system. A minimum SEC of 3.8 MJ/kg was recorded using the combined infrared-hot air convection (IR-HA) drying system, which was 91.7% and 51.7% lower than convective and IR dryers, respectively. The present study suggested a combination of IR and hot air convection at 60 °C, 0.3 W/cm2 and 0.5 m/s as optimum conditions for efficient drying of biomass with a high water content.

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