Drying Model, Shrinkage and Energy Consumption Evaluation of Air Dried Sheet Rubber Drying System for Small Enterprise

2012 ◽  
Vol 622-623 ◽  
pp. 1135-1139 ◽  
Author(s):  
A. Ekphon ◽  
T. Ninchuewong ◽  
S. Tirawanichakul ◽  
Y. Tirawanichakul

The main objective of this research was to study drying kinetics of air dried sheet (ADS) rubber using hot air and simulated drying kinetics by empirical model compared to experimental results. The 10-15 fresh rubber sheet with initial moisture content ranging of 23-40% dry-basis was dried by temperature of 40-70°C and air flow rate of 0.7 m/s. The fresh rubber sheet samples were dried until the desired final moisture content reached to 0.15% dry-basis. The experimental results showed that the drying rate of ADS rubber dried with hot air convection was faster than conventional natural air convection and drying rate was related to drying temperature. The experimental data was statistical non-linear regression analyzed by using 10 conventional empirical models. The coefficient of determination (R2) and root mean square error (RMSE) values were used as the criteria for selecting the best equation to describe the experimental data The results showed that the calculated results of Verma et al.’ model had a good relation to the experimental results. For specific energy evaluation, the results showed that at high drying temperature specific energy consumption of ADS rubber was relatively low compared to drying with low temperature. Finally, the determination of physical quality showed that.

2019 ◽  
Vol 801 ◽  
pp. 345-350
Author(s):  
Ratinun Luampon ◽  
Sungwarn Bunchan ◽  
Bundit Krittacom

This research was proposed to applying stainless wire mesh porous material for specific energy consumption improvement of a hot air dryer. In experimental consist two main parts, first part was a comparison of drying with and without hot air recirculation duct. Second part was a comparison of drying with and without stainless wire mesh porous material in drying chamber and hot air recirculation duct. Tilapia was drying product, stainless wire mesh in drying chamber was constant PPI=8 and 6 layers, stainless wire mesh in hot air recirculation duct was constant PPI=8 and varied layer at 6, 8 and 12 layers and hot air recirculation ratio 40%, 60% and 80%. Experimental result was, drying with hot air recirculation duct was higher drying rate than without recirculation duct and drying rate was increased, drying time was decreased and SEC was decreased with increased hot air recirculation ratio. At recirculation ratio 80%, SEC was lowest and decreased to 54.52% compared with without recirculation duct. Therefrom, the stainless wire mesh porous materials were inserted in the drying chamber and recirculation duct at PPI=8, 6 layers and PPI=8, 12 layers, respectively and used recirculation ratio 80%, it was found that SEC was lowest and decreased as about 62.21%.


2013 ◽  
Vol 19 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Esmaeili Adabi ◽  
Ali Motevali ◽  
Ali Nikbakht ◽  
Hadi Khoshtaghaza

Massive consumption of energy in drying industry makes it a matter of challenge regarding economical aspects and limited recourses. Several methods for drying including hot air convection, vacuum, infrared and hot air convection-infrared technologies were applied in order to estimate the consumed energy during the drying of mulberry fruit. Moreover, microwave heating, chemical (ethyl oleate and potassium), mechanical (ultrasonic) and blanching (hot water) pretreatments were compared. According to the Results, maximum energy consumption was recorded when no pretreatment was performed. Microwave heating in the hot air convection-infrared dryer resulted in the lowest consumption of energy. Total energy requirement decreased with the temperature in the convection dryer res. Conversely, energy increased with air velocity. The vacuum dryer consumed the highest amount of energy which was measured to be 46.95 kWh while the lowest energy was recorded with using infrared-convective dryers. Also Experimental results showed that minimum and maximum specific energy consumption in the drying of black mulberry were associated with microwave pretreatment in IR-hot air dryer and control treatment in vacuum dryer, respectively. The minimum color change (?E) for drying of black mulberry was found in microwave pretreated samples dried with the vacuum dryer, yet maximum ?E was observed in hot air dryer when no pretreatment was applied.


2012 ◽  
Vol 622-623 ◽  
pp. 1580-1585
Author(s):  
A. Sae-Khow ◽  
S. Tirawanichakul ◽  
Y. Tirawanichakul

The objective of this research were to evaulate equilibrium moisture contents (EMC) of black pepper using the gravimetric-static method and to study the drying kinetics of pepper using 1-stage hot air (HA) drying, 1-stage infrared (IR) drying, 2-stages drying with microwave (MW) and IR and 2-stages drying with MW and HA including to the specific energy consumption determination. For the first objective, the five saturated salt solutions were used for providing equlibrate state between pepper and surrounding at temperature ranging of 40-65°C correlated to relative humidity ranging of 10-90%. The results showed that EMC value decreased with increasing temperature at constant relative humidity. To evaluate the EMC value, the experimental data was simulated by four conventional EMC models and the criteria of the best fiiting models were determined by the determination of coefficient (R2) and the root mean square error (RMSE) value. The results showed that the calculated value using the Modified Oswin model was the most suitable for describing the relationship among equilibrium moisture content, relative humidity and temperature. To study effect of drying condition on drying kinetics, the initial moisture content and final moisture content after drying of papper sample was in ranges of 300-400% dry-basis and 12-16% dry-basis, respectively. The experimetal data were simulsted using empirical drying models and the results showed that the drying temperature relatively affected to drying rate of pepper while the evolution of moisture transfer was in the drying falling ratefor all drying strategies. The 1-stage IR drying and 2-stages drying with MW and IR provided low specific energy consumption (SEC) (0.11-0.15 MJ/kg of water evaporated) compared to the other drying strategies (0.87-1.52 MJ/kg of water evaporated). Moreover, the SEC of pepper drying decreased with increasing of drying temperature.


2013 ◽  
Vol 844 ◽  
pp. 502-506 ◽  
Author(s):  
Chayut Nuntadusit ◽  
Makatar Waehahyee

In the process for producing ribbed smoked rubber sheet, the rubber sheet drying is the most time and energy consumption process. This research study the possibility in develop new drying system using array of hot air jets impinging directly on rubber sheet in order to reduce time for drying rubber in smoked room and increase productivity of rubber sheets. In the study, the array of jets from jet plate with drilled jet holes in staggered arrangement impinged on the both side of rubber sheet. The effects of jet velocity (Vj=10, 16, 23 m/s), jet temperature (Tj=50, 60, 70°C) and the distance from jet outlet to rubber surface (L=4D, 6D, 8D which D is diameter of jet hole) on drying rate were investigated by measuring weight of rubber sheet change with time. The heat transfer rate on impinged surface was also measured by attaching a heat flux sensor on impinged wall. The results showed that the convective heat transfer coefficient increased when the jet velocity was increased and when the distance from jet was decreased particularly in jet directly impinged region. It was found that the enhancement in heat transfer rate from jets cannot increase the rubber drying rate for all cases because the drying rate depend on rubber property. The process of rubber sheet drying can be divided in 2 periods; in the first drying period, the drying rate decreases with decreased moisture content. The drying rate depended on the initial moisture content and the condition of external effect such as jet velocity, jet temperature and distance from jet outlet to rubber surface. In second drying period, the moisture content is below 20% dry basis. In this period, the drying rate is almost constant near zero. It was also found that the drying for case of L=6D was higher than case of L=4D and 8D. The optimum condition for rubber sheet drying without defects on rubber property after drying was L=6D and Tj=70°C.


1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  


2014 ◽  
Vol 10 (2) ◽  
pp. 269-280 ◽  
Author(s):  
Hosain Darvishi ◽  
Mohammad Zarein ◽  
Saied Minaei ◽  
Hamid Khafajeh

Abstract The energy and exergy analysis, drying characteristics and mathematical modeling of the thin-layer drying kinetics of white mulberry using microwave drying were investigated. Results indicated that values of exergy efficiency (33.63–57.08%) were higher than energy efficiency (31.85–55.56%). Specific energy consumption increased with increasing microwave power while improvement potential decreased. The specific energy consumption and improvement potential varied from 3.97 to 6.73 MJ/kg water and 0.71 to 2.97 MJ/kg water, respectively. Also, energy efficiency decreased with decrease in moisture content and microwave power level. The best exergy and energy aspect was obtained by drying at 100 W microwave power. Drying took place mainly in warming up, constant rate and falling rate periods. The Page model showed the best fit to experimental drying data. Effective diffusivity increased with decreasing moisture content and increasing microwave power. It varied from 1.06 × 10−8 to 3.45 × 10−8 m2/s, with an energy activation of 3.986 W/g.


BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9429-9443
Author(s):  
Xiaoxue Du ◽  
Hanping Mao ◽  
Chunguang Wang

The rheological properties of the compression process of sweet sorghum straw were studied. The selected experimental factors comprised of the compression density, cutting length, compression speed, and moisture content, and specific energy consumption were selected as the evaluation index of the compression characteristics. The Box-Behnken test scheme was used to analyze the response surface test. The results showed that the selected compression model and specific energy consumption model of the sweet sorghum straw compression process were obtained. The primary factors contributing to energy consumption were the cutting length, moisture content, and compression density. The optimal parameters were as follows: a compression density of 500 kg/m3, a cutting length of 20 mm to 30 mm, a moisture content of 60.06%, and a specific energy consumption of 66 kJ/kg. The results provided methods for reducing the total energy consumption of the compression process and a theoretical basis for the compression and bundling of sweet sorghum.


2018 ◽  
Vol 192 ◽  
pp. 03023
Author(s):  
Natthacha Chaloeichitratham ◽  
Pornkanya Mawilai ◽  
Thadchapong Pongsuttiyakorn ◽  
Pimpen Pornchalermpong

In this study, the effects of two drying methods: hot-air and freeze drying for Thai green curry paste in a terms of drying time and qualities have been investigated. The hot-air drying was carried out in tray dryer at temperature of 50, 60 and 70 °C. The freeze drying was carried out in freeze dryer at freezing temperature of -20°C, primary drying temperature of -10°C and secondary drying temperature of 50°C. Moisture content, water activity, colour, bulk density, and total phenolic content (TPC) were determined in samples. Freeze dried sample had significantly (p<0.05) lower moisture content, water activity, bulk density, total colour difference and browning index than hot air dried samples. For antioxidant activity, the results showed hot-air drying at 70°C effected highest TPC similar to freeze drying.


Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 240 ◽  
Author(s):  
Choong Oon Choo ◽  
Bee Lin Chua ◽  
Adam Figiel ◽  
Klaudiusz Jałoszyński ◽  
Aneta Wojdyło ◽  
...  

This study aims to reduce the amount of specific energy consumed during the drying of fresh Murraya koenigii leaves by comparing four drying methods: (1) convective hot-air drying (CD; 40, 50 and 60 °C); (2) single-stage microwave-vacuum drying (MVD; 6, 9 and 12 W/g); (3) two-stage convective hot-air pre-drying followed by microwave-vacuum finishing–drying (CPD-MVFD; 50 °C, 9 W/g); and (4) freeze-drying as a control in the analysis sections. The drying kinetics were also modelled using thin-layer models. The quality parameters of dried M. koenigii leaves were measured including total polyphenolic content (TPC), antioxidant capacity (ABTS and FRAP), profiling of volatile compounds, colour analysis and water activity analysis. Results showed that CPD-MVFD effectively reduced the specific energy consumption of CD at 50 °C by 67.3% in terms of kilojoules per gram of fresh weight and 48.9% in terms of kilojoules per gram of water. The modified Page model demonstrated excellent fitting to the empirical data obtained. FD showed promising antioxidant activity. The major contributor of antioxidant capacity was TPC. The volatile compounds profiled by gas chromatography-mass spectrometry, namely, β-phellandrene (31%), α-pinene (19.9%), and sabinene (16%) were identified as the major compounds of dried M. koenigii leaves. Colour analysis showed MVD’s high performance in preserving the colour parameters of M. koenigii leaves under all conditions. The colour parameters were correlated to the antioxidant capacity and TPC. Water activity analysis showed that the water activity of M. koenigii leaves for all drying methods indicating that the conditions were microbiologically and shelf-stable. Pearson correlation showed the colour parameters of the leaves had a strong correlation to TPC. Overall, MVD showed promising energy consumption reduction and recovery in TPC and volatile compounds.


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