scholarly journals Microwave drying behaviour of tomato slices

2013 ◽  
Vol 31 (No. 2) ◽  
pp. 132-138 ◽  
Author(s):  
S. Çelen ◽  
K. Kahveci
Keyword(s):  
Energy Consumption ◽  
Theoretical Model ◽  
Microwave Power ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Microwave Drying ◽  
Drying Rate ◽  
Drying Time ◽  
Drying Behaviour ◽  
Drying Conditions

The microwave drying behaviour of tomato slices was investigated experimentally to determine the effects of microwave power on the drying rate, energy consumption, and dried product quality in terms of colour, and a theoretical model was proposed to define the drying curves of tomato slices. The experiments performed with the microwave power of 90, 180, 360, and 600 W indicate that the drying time and the energy consumption decreased considerably with an increase in microwave power. The experiments also revealed that the drying rate shows first an increase and then a decrease during drying, and that the colour quality of the product deteriorates significantly with the increase of the microwave power. A theoretical model was developed using the solution of energy equation considering the microwave power as an internal heat source. The electric field strength inside the material was assumed to be dependent on the moisture content and the constants emerging from this assumption were obtained by minimising the sum of squared differences between the theoretical results and experimental data obtained for various drying conditions. The results show that the values proposed for the constants provide a good agreement between the theoretical and experimental drying behaviour.  

scholarly journals Microwave Drying Characteristics and Drying Quality Analysis of Corn in China

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1511
Author(s):  
Haili Liu ◽  
Haoyu Liu ◽  
Heyun Liu ◽  
Xu Zhang ◽  
Qingchao Hong ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Microwave Power ◽  
Early Stage ◽  
Microwave Drying ◽  
Quality Analysis ◽  
Drying Rate ◽  
Drying Characteristics ◽  
Drying Conditions ◽  
Opposite Tendency

To identify the microwave drying characteristics of corn, microwave drying tests were conducted on corn. By taking the moisture content, drying rate, and drying temperature as indices, this research revealed the effects of different microwave powers and loads on the microwave drying characteristics of corn. Moreover, energy consumption and quality of dried corn were analysed under different drying conditions. The results demonstrate that microwave drying has significant energy-saving effects. The energy consumption by microwave drying is less than 0.3 times that used by electrothermal drying under the same load. Both microwave power and load exert significant influences on drying characteristics. Higher microwave power results in a greater average drying rate, wherein shorter periods of time are required to reach the maximum drying rate and higher temperatures of the corn. However, the load shows the opposite tendency. The smaller the load, the higher the temperature of the corn in the early stage of drying. However, as drying continues, the temperature curve changes significantly, and the temperature rises with the increase in load in the later stage of drying. In consideration of energy consumption and dried quality, the load of corn should be increased as appropriate, and the microwave intensity should be limited to no higher than 0.7 W/g in the experiment.

Single Layer Drying Behavior of Apple Slices in a Microwave Dryer

2011 ◽  
Vol 312-315 ◽  
pp. 842-847 ◽  
Author(s):  
Soner Çelen ◽  
Kamil Kahveci ◽  
Ugur Akyol
Keyword(s):  
Microwave Power ◽  
Colour Change ◽  
Single Layer ◽  
Drying Time ◽  
Apple Slices ◽  
Drying Behavior ◽  
Drying Behaviour ◽  
Drying Conditions ◽  
Mean Square Errors ◽  
Microwave Dryer

In this study, the drying behaviour of single layer apple slices of 5mm thickness in a microwave dryer was investigated experimentally for four different microwave power levels (90 W, 180 W, 360 W and 600 W) and suitability of drying models available in the literature in simulating the drying behaviour of apple slices was determined by statistical analysis. The performance of these models was determined by comparing the coefficients of determination (R), reduced chi-squares (χ2) and root mean square errors (RMSE) of the models. The results show that drying time and energy consumption decreases considerably with increasing microwave power. The results also show that, among of the models proposed, the Verma et al. model gives the best fit with experimental data for all drying conditions considered. In order to determine the colour change of apple, a colour meter was also used in this study and found that L* and a* values were not significantly different from the values of the fresh apples.

Calculation of Moisture Content and Drying Rate during Microwave Drying

2013 ◽  
Vol 423-426 ◽  
pp. 746-749
Author(s):  
Samad Khani Moghanaki ◽  
Behnam Khoshandam ◽  
Mohammad Hosein Mirhaj
Keyword(s):  
High Temperature ◽  
Moisture Content ◽  
Microwave Power ◽  
Operating Temperature ◽  
Irradiation Time ◽  
Microwave Drying ◽  
Drying Rate ◽  
Microwave Method ◽  
Drying Process ◽  
Drying Time

Convectional dryerswork at high temperature and usually lead to loss of quality for sensitivebiomaterial products (especially in nutrition). In this way the researchersfound the microwave power more effective and suitable for drying processes. Someof microwave drying advantages include the following: short drying time, highquality of product, low operating temperature, flexibility in producing widerange of products and easier process controlling. The article calculated themoisture content and drying rate during drying process. Microwave power, holdertray speed, dimension of samples, irradiation time were considered; under theseconditions experiments were done and the results show that microwave method hasmore advantages as comparing with convectional methods.

Microwave Drying Characteristics of Soybeans in Single and Variable Microwave Power Density

2017 ◽  
Vol 13 (4) ◽  
Author(s):  
Ruifang Wang ◽  
Lijuan Zhang ◽  
Kun Lei ◽  
Qing Xu ◽  
Wei Tian ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Power Density ◽  
Microwave Power ◽  
Lower Energy ◽  
Microwave Drying ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Characteristics ◽  
Single Power ◽  
Energy Aspects

Abstract Drying characteristics of soybeans under different microwave (MW) processing schemes were studied in regard to energy aspects. For drying in a single microwave power density, the experiments were carried out at a constant MW output power throughout the process. It was found that the drying rate is enhanced together with reduced energy consumption at higher single power density, but the soybean cracking ratio is increased gradually from 2 % to 40 % when the power density was changed from 0.2 W/g to 0.8 W/g. Efforts were made to reach a compromise between the drying rate and dried soybean quality by varying the MW power density in several steps overall the drying process, but soybean cracking occurred at a higher ratio due to the fluctuation of drying rate. Microwave drying of soybeans under the power density less than 0.2 W/g with slow and stable drying rate can achieve the soybean cracking ratio controlled within 5 % and lower energy consumption.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

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

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.

Water migration in poplar wood during microwave drying studied by time domain nuclear magnetic resonance (TD-NMR)

Holzforschung ◽  
2017 ◽  
Vol 71 (11) ◽  
pp. 881-887 ◽  
Author(s):  
Xinyu Li ◽  
Yulei Gao ◽  
Minghui Zhang ◽  
Ximing Wang ◽  
Xinyue Wei
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Time Domain ◽  
Bound Water ◽  
Free Water ◽  
Microwave Drying ◽  
Drying Rate ◽  
Drying Time ◽  
The Time Domain ◽  
Nuclear Magnetic

AbstractThe migration of bound water and free water has been investigated during microwave drying of wood by the time domain nuclear magnetic resonance (TD-NMR) technique. Both the heartwood (hW) and sapwood (sW) of Beijing poplar (Populus beijingensisW. Y. Hsu) and Qingpi poplar (Populus platyphyllaT. Y. Sun) were studied. The microwave drying is characterized by a fast drying rate, and there is a linear relation between moisture content (MC) and microwave drying time (t). The drying rate of free water is about 2.7 times more rapid than that of bound water. The spin-spin relaxation time (T2) revealed that most of the water was free water situated in smaller pores. The irregular T2 signal amplitudes of free water in hWs indicated that fractional water in smaller pores was transferred into bigger pores during drying.

Moisture Diffusivity and Energy Consumption during Microwave Drying of Plaster of Paris

2010 ◽  
Vol 5 (1) ◽  
Author(s):  
Magesh Ganesh Pillai ◽  
Iyyasamy Regupathi ◽  
Lima Rose Miranda ◽  
Thanapalan Murugesan
Keyword(s):  
Energy Consumption ◽  
Initial Moisture Content ◽  
Moisture Diffusivity ◽  
Operating Conditions ◽  
Microwave Drying ◽  
Effective Moisture Diffusivity ◽  
Experimental Conditions ◽  
Drying Time ◽  
Plaster Of Paris ◽  
Effective Moisture

The drying characteristics of plaster of paris (POP) under microwave conditions at different microwave power input, initial moisture content, sample thickness and drying time were studied. Further the experimental data on moisture ratio of POP for different operating conditions were obtained and calculations were made using nine basic drying model equations. The appropriate model with modified constants and coefficients to represent the drying kinetics of POP was found through the analysis of the statistical analysis. The effective moisture diffusivity of the drying process was also computed for different experimental conditions and a relationship between the drying rate constant and the effective moisture diffusivity was obtained. The energy consumption for microwave drying of plaster of paris at different experimental conditions were also computed.

Research on Constant-Temperature Drying Test of Cotton Straw and Regression Analysis of Drying Rate

2012 ◽  
Vol 472-475 ◽  
pp. 1645-1651
Author(s):  
Jian Jun Hu ◽  
Sheng Qiang Shen ◽  
Ting Zhou Lei ◽  
Hao Huang ◽  
Quan Guo Zhang
Keyword(s):  
Regression Analysis ◽  
Constant Temperature ◽  
Initial Moisture Content ◽  
Drying Rate ◽  
Regression Equations ◽  
Drying Time ◽  
Drying Curves ◽  
Drying Technology ◽  
Drying Conditions ◽  
Two Stages

Constant-temperature drying tests for cotton straw under different conditions were performed with an integrated thermal analyzer, and the influence of different drying conditions on the drying process was analyzed. The process was divided into preheating stage, constant-rate drying stage, and decelerating drying stage. Regression analysis was conducted for drying curves at the latter two stages, and then the drying time at the critical point was determined. Regression equations of drying rate at these stages were produced. Research results showed that the decelerating drying stage of cotton straw included two decelerating intervals, and the best ending point of the drying of the cotton straw that had an initial moisture content of 56.1% and a drying temperature of 100°Cwas 600s, thus providing experimental data and reference for research on drying technology of straws.

Study on Microwave Drying Process and Drying Characteristics of Sewage Sludge

2013 ◽  
Vol 838-841 ◽  
pp. 2643-2647
Author(s):  
Jin Ping Li ◽  
Meng Yao Li ◽  
Wen Yao ◽  
Ni Wang
Keyword(s):  
Energy Consumption ◽  
Sewage Sludge ◽  
Lower Energy ◽  
Microwave Drying ◽  
Drying Rate ◽  
Municipal Sludge ◽  
Drying Process ◽  
Drying Characteristics ◽  
Pretreatment Time ◽  
Short Time

Combination of oven and microwave and only oven are two ways to study municipal sludge,and it investigates whether different size, microwave drying pretreatment, pretreatment time and oven temperature characteristics have effect on drying characteristics. The results shows that: using microwave to dry sludge need short time, the drying rate is fast, combination of oven and microwave has higher drying rate and lower energy consumption than only oven.

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