Constant Temperature Drying Rate Tester: Real-Time Water Evaporation Measurement of Fabrics

Eggplant is a familiar and admired vegetable in Bangladesh. It is a highly perishable vegetable and cannot be preserved long. Drying is an ancient preservation method used to extend shelf-life of fruits and vegetables. Different Pretreatments may affect the drying kinetics of foods. A study was conducted to evaluate how pretreatments affect the drying behavior of eggplant. Proximate composition of fresh eggplant was analyzed. The samples of constant thickness (8 mm) were dried at 50°C, 55°C and 60°C to determine the effect of temperature on drying rate constant, while for determining the effect of thickness on rate constant, eggplant slices of 4, 6 and 8 mm thicknesses were dried at a constant temperature of 55°C. It was observed that, drying rate decreased with the increase in thickness and the index ‘n’ was found to be 0.89 at 55°C. Under similar drying condition at constant thickness (8 mm), drying time showed an inverse relationship with temperature. The activation energy (Ea) was calculated as 3.242 Kcal/g-mole. Eggplant slices having the highest thickness (8 mm) were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes, respectively using hot water bath to determine the effective blanching time and temperature. It was observed that the samples blanched at 75°C and 80°C for 2 minute were enough to inactivate the enzymes. Pretreated (blanched, sulphited and blanched plus sulphited) eggplant slices having constant thickness (8 mm) were dried at constant temperature of 55°C. The drying time was influenced by pretreatments. The highest drying rate was observed for eggplant slices with blanched plus sulphited (5% KMS solution) samples while eggplant slices with 5%KMS solution dipped for 10 minutes showed the lowest drying rate. In case of fresh slices, drying time was lower than blanched and sulphited samples but higher than blanched plus sulphited samples. Pretreatment was also found effective on the color changes (preservation or degradation). Blanching gave a bright color compared to fresh sample but less bright compared to sulphited samples. In case of SO2 retention, blanched plus sulphited sample showed higher retention than sulphited sample. Sulphited sample retains 44.8 ppm SO2/100g of sulphited sample, while the blanched plus sulphited sample retains 280 ppm SO2/100 g of blanched plus sulphited sample. J. Bangladesh Agril. Univ. 17(1): 105–109, March 2019

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.472-475.1645 ◽

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.

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Influence of Soil Suction and Environmental Factors on Drying Characteristics of Granular Subgrade Soils

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1714-13 ◽

2000 ◽

Vol 1714 (1) ◽

pp. 98-106

Author(s):

W. Virgil Ping ◽

Ching-Chin Ling ◽

Robert K. H. Ho

Keyword(s):

Relative Humidity ◽

Water Evaporation ◽

Granular Soils ◽

Drying Rate ◽

Soil Drying ◽

Soil Suction ◽

Direct Effects ◽

Drying Characteristics ◽

Subgrade Soils ◽

Excessive Water

According to contractors in Florida, construction problems have emerged because pavement soils hold excessive water and are difficult to dry and compact. Recent research on the effects of soil suction and environmental conditions on drying rate characteristics of six types of troublesome granular soils is presented. Two types of tests were conducted for the study: soil suction tests using the thermocouple psy-chrometer method and drying rate tests using an environmental chamber. The experimental results showed that both the soil suction and relative humidity had direct effects on the soil-drying rate. The drying rate decreased with an increase in soil suction for each soil type and also decreased with an increase in the percentage of fines. The influence of relative humidity on the soil-drying rate was much more significant than the effect of the temperature. The rate of water evaporation was extremely low for the soils with a higher percentage of fines when the relative humidity was high. The A-2-4 soils with greater than 20 percent of fines may have such a low drying rate in an environment with high relative humidity that they are difficult to handle during construction.

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Real-time direct measurement of liquid (water) evaporation by simple disturbance inhibited interfometry technique

Journal of the Korean Physical Society ◽

10.3938/jkps.71.554 ◽

2017 ◽

Vol 71 (9) ◽

pp. 554-560

Author(s):

Yong Gi Kim

Keyword(s):

Real Time ◽

Direct Measurement ◽

Liquid Water ◽

Water Evaporation

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Evaluation of a Moisture Diffusion Model for Analyzing the Convective Drying Kinetics of Lavandula x allardii Leaves

Computation ◽

10.3390/computation9120141 ◽

2021 ◽

Vol 9 (12) ◽

pp. 141

Author(s):

Vasileios Chasiotis ◽

Dimitrios Tzempelikos ◽

Andronikos Filios

Keyword(s):

Diffusion Model ◽

Moisture Transfer ◽

Variable Temperature ◽

Moisture Diffusion ◽

Drying Kinetics ◽

Convective Drying ◽

Water Evaporation ◽

Drying Rate ◽

Computationally Efficient ◽

Kinetics Of

In the present case study, a moisture diffusion model is developed to simulate the drying kinetics of Lavandula x allardii leaves for non-stationary convective drying regimes. Increasing temperature profiles are applied over the drying duration and the influence of temperature advancing rates on the moisture removal and the drying rate is investigated. The model assumes a one-dimensional moisture transfer under transient conditions, which occurs from the leaf center to the surface by liquid diffusion due to the concentration gradient developed by the surface water evaporation caused by the difference of water vapor partial pressure between the drying medium and the leaf surface. A numerical solution of Fick’s 2nd law is obtained by an in-house code using the finite volume method, including shrinkage and a variable temperature-dependent effective moisture diffusion coefficient. The numerical results have been validated against experimental data for selected cases using statistical indices and the predicted dehydration curves presented a good agreement for the higher temperature advancing rates. The examined modeling approach was found stable and can output, in a computationally efficient way, the temporal changes of moisture and drying rate. Thus, the present model could be used for engineering applications involving the design, optimization and development of drying equipment and drying schedules for the examined type of non-stationary drying patterns.

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Electrically enhanced drying of white champignons

Proceedings of 21th International Drying Symposium ◽

10.4995/ids2018.2018.7318 ◽

2018 ◽

Author(s):

Alex Martynenko ◽

Ivanna Bashkir ◽

Tadeusz Kudra

Keyword(s):

Moisture Content ◽

Initial Moisture Content ◽

Cross Flow ◽

Water Evaporation ◽

Drying Rate ◽

Residual Water ◽

Ionic Wind ◽

Air Stream ◽

Wide Range ◽

Forced Air

Effects of convective cross-flow of air in electrohydrodynamic (EHD) drying on drying rate of 5 mm slices of champignons have been investigated. Electro-convection issued from discharge electrode (42 needles arranged into 6×7 rows with 2×2 cm spacing, 18 kV DC voltage and 3.5 cm gap) provided average ionic wind velocity of 1.0 m/s flowing perpendicularly to the surface of champignons slices, while forced air stream at atmospheric pressure 1000 kPa, superficial velocity 1.0 m/s, temperature 22-24°C, and relative humidity 25-40%, was blown parallel to the surface of champignons slices. To study interactions between forced air cross-flow and electro-convection, the experimental protocol was designed, exploring three cases in various combinations: (1) Sole EHD, (2) air cross-flow, and (3) EHD with simultaneous air cross-flow. The case # 3 was found to be the most efficient, resulting in 10.2 g/h of water evaporation whereas drying rate was 6.6 g/h (# 1) and 3.6 g/h for (# 2). Such numbers imply that these effects are additive. In some combinations the effect of air cross-flow was the same (3.6 g/g), but electro-convection was significantly suppressed to 3.2 g/h likely because air stream removed surface water, which reduced charge transfer and electro-diffusion.In trials with different initial moisture content it was found that drying kinetics followed exponential decay in the wide range of initial moisture contents from 4.9 to 12.0 g/g (db). Drying rate due to forced air convection was found to be independent of moisture content, whereas drying rate due to electro-convection significantly depended on the moisture content. For example, the EHD drying rate of fresh-cut champignons slices with initial moisture content 10.74 g/g was 0.237 g/h, while the slices after two days in the cooler (initial moisture content dropped to 4.92 g/g) it was 0.418 g/h. Also, it was found that electro-convective drying could not remove all residual water. At the end of drying the equilibrium moisture content attained 0.2 - 0.3 g/g (aw~0.3).It appears that performance of EHD drying depends also on the product porosity as water can exist as free in open pores or be trapped in closed pores. In some experiments we observed rotation of champignon slices in the plane perpendicular to ionic wind. It happened at the end of drying when slices were light enough to be lifted by electrostatic force and dragged by the vortex. This phenomenon could be attributed either to the effect of DC electric field on polarized water molecules trapped in closed pores, or it could be electrostatic effect of ionic wind on charged porous body. Also, the hypothesis that EHD has both linear and rotational (vortex) components require further investigation.

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Curing monitoring of bonded composite patch at constant temperature with electromechanical impedance and system parameters evaluation approach

Smart Materials and Structures ◽

10.1088/1361-665x/ac3d72 ◽

2021 ◽

Vol 31 (1) ◽

pp. 015039

Author(s):

Jianjian Zhu ◽

Jinshan Wen ◽

Chunyang Chen ◽

Xiao Liu ◽

Zifeng Lan ◽

...

Keyword(s):

Real Time ◽

Constant Temperature ◽

Patch Repair ◽

Curing Process ◽

Real Time Monitoring ◽

Electromechanical Impedance ◽

System Parameters ◽

Composite Patch ◽

Repair Patch ◽

Bonded Composite

Abstract As one of cost-effective maintenance methods, bonded composite patch repair has been receiving more and more attention in the engineering community since past decades. However, realizing real-time monitoring for curing process of bonded repair patch is difficult for most current techniques. In our work, a method based on electromechanical impedance and system parameters evaluation for structural health monitoring issues was developed, which could implement the online monitoring throughout whole curing process. Compared with the dynamic thermomechanical analysis results, the experiment data matches well. It demonstrates that the proposed approach can effectively monitor the curing process of composite repair patch at a constant temperature of 120 °C. Hence, the presented approach in this paper is expected to be a novel, robust, and real-time monitoring method for structural maintenance with the composite patch.

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