Effect of air Recirculation on Moisture Removal Efficiency in Combined Hydrolytic–Aerobic Rotary Bio-Drying Process

Objectives : The effects of temperatures of supplied air and exhaust gas on moisture removal in the bio-drying process of sewage sludge were assessed by simulating the process. We also suggested performance and efficiency indicators for moisture removal in this process and identified their effectivity.Methods : The bio-drying process of sewage sludge was simulated by mathematical modeling of heat and mass balance under different combinations of supplied-air temperatures and control ranges of exhaust gas temperatures. The simulation results were analyzed by using some indicators for assessing the performance and efficiency of moisture removal.Results and Discussion : While BVS (biodegradable volatile solid) degradation was inhibited at a higher supplied-air temperature and a lower control range of exhaust gas temperature, moisture reduction was enhanced at the supplied-air temperature nearer to ambient and the controlled exhaust gas temperature for 45 to 50℃. The drying performance could be improved by the utilization of both metabolic heat and convective heat from hot supplied-air for the source of heat necessary for moisture removal. We suggested the moisture removal rate as a performance indicator, and both the moisture removing capacity of supplied-air and the mass ratio of moisture removal to BVS degradation as an efficiency indicator. We identified that this mass ratio could be an alternative for thermal efficiency of drying.Conclusions : It is effective to control the air-flow rate to keep the exhaust gas temperature within 45~50℃ during bio-drying of sewage sludge in terms of drying performance and efficiency. It is expected that a specified range or minimum required value for the performance and efficiency indicators in the bio-drying process which suggested in this study needs to be established.

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USE OF THE S-40 DRYER IN TWO-STAGE DRYING OF CORN GRAIN

AGRICULTURAL ENGINEERING ◽

10.26897/2687-1149-2021-3-69-73 ◽

2021 ◽

pp. 69-73

Author(s):

MIKHAIL G. ZAGORUIKO ◽

◽

SERGEY A. PAVLOV ◽

Keyword(s):

Moisture Content ◽

Standard Method ◽

Starch Content ◽

Moisture Removal ◽

Drying Process ◽

Two Stage ◽

Drying Technology ◽

Reversible Component ◽

Corn Grain

The paper provides rationale for safe modes and methods for calculating a two-stage drying technology with partial recirculation of grain, in which the grain is under-dried by 2…3% to the standard humidity in a grain dryer, and the hot grain is cooled by active ventilation with outside air, while drying it to the standard humidity. The safe mode of two-stage drying in S-40 provides for partial recirculation of grain with moisture removal close to the standard, and the moisture content of the recirculated mixture not exceeding 18%. The recirculation coeffi cient calculated based on this condition is used to determine the temperature of the recirculating grain mixture, taking into account the reversible component in the shaft dryer. The minimized recirculation ratio provides for the permissible unevenness in drying and minimal fracturing. The recirculation drying process was analyzed according to the standard method, but with the adjusted values of moisture removal and temperature of the grain mixture. Economic tests of the S-40 dryer were carried out using a two-stage technology on corn grain. It has been experimentally established that the S-40 dryer with a recirculation coeffi cient of 2 and a moisture pick-up of 4% per cycle when drying corn grain with a moisture content of 23.5 to 15.6%, at a drying agent temperature of 95°C, provides a throughput of 10 t/h (without refrigeration). Cooling was carried out in the warehouse. No signifi cant changes in the quality of dried and cooled grain have been established: the starch content and fracturing practically did not change; the unevenness of the dried seeds did not exceed the original requirements. The expediency of using the S-40 direct-fl ow dryer in the recirculation mode has been experimentally established.

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Model for Thin Layer Drying of Lemongrass (Cymbopogon citratus) by Hot Air

Processes ◽

10.3390/pr7010021 ◽

2019 ◽

Vol 7 (1) ◽

pp. 21 ◽

Cited By ~ 16

Author(s):

Thi Van Linh Nguyen ◽

My Duyen Nguyen ◽

Duy Chinh Nguyen ◽

Long Giang Bach ◽

Tri Duc Lam

Keyword(s):

Activation Energy ◽

Diffusion Coefficient ◽

Effective Diffusion Coefficient ◽

Removal Rate ◽

Effective Diffusion ◽

Suitable Model ◽

Moisture Removal ◽

Drying Process ◽

Drying Temperature ◽

Thin Layer Drying

Lemongrass is a plant that contains aromatic compounds (myrcene and limonene), powerful deodorants, and antimicrobial compounds (citral and geraniol). Identifying a suitable drying model for the material is crucial for establishing an initial step for the development of dried products. Convection drying is a commonly used drying method that could extend the shelf life of the product. In this study, a suitable kinetic model for the drying process was determined by fitting moisture data corresponding to four different temperature levels: 50, 55, 60 and 65 °C. In addition, the effect of drying temperature on the moisture removal rate, the effective diffusion coefficient and activation energy were also estimated. The results showed that time for moisture removal increases proportionally with the air-drying temperature, and that the Weibull model is the most suitable model for describing the drying process. The effective diffusion coefficient ranges from 7.64 × 10−11 m2/s to 1.48 × 10−10 m2/s and the activation energy was 38.34 kJ/mol. The activation energy for lemongrass evaporation is relatively high, suggesting that more energy is needed to separate moisture from the material by drying.

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Effect of aeration strategy on moisture removal in bio-drying process with auto-controlled aeration system

Drying Technology ◽

10.1080/07373937.2021.1912080 ◽

2021 ◽

pp. 1-15

Author(s):

Jae-Ram Park ◽

Dong-Hoon Lee

Keyword(s):

Moisture Removal ◽

Drying Process ◽

Aeration System

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Variations of Moisture Content in The Presence of Combined Flux

JOURNAL OF ADVANCES IN MATHEMATICS ◽

10.24297/jam.v14i1.7275 ◽

2018 ◽

Vol 14 (1) ◽

pp. 7624-7630

Author(s):

Alpna Mishra ◽

Sanjeev Kumar

Keyword(s):

Differential Equation ◽

Partial Differential Equation ◽

Diffusion Coefficient ◽

Moisture Content ◽

Pressure Gradient ◽

Moisture Removal ◽

Drying Process ◽

Partial Differential ◽

Latent Energy ◽

Mechanical Methods

A model for diffusion in grains, through the drying process in the form of moisture removal, discussed through this work. While in drying, the moisture leaves the product as vapour or gas. This is achieved by impairing energy to the moisture molecule or changing the environment, so that the molecule will have sufficient latent energy to leave the product. Hence it is the process, which is intended to remove moisture from a feed substance so that the feed becomes dry as final product. Moisture reduction can also be achieved by mechanical methods. Using the pressure gradient as the deriving force with combined flux, we get a system of partial differential equation which will be then solved with the help of MATLAB 7.0 and finally the graphs shows the variation of moisture with respect to diffusion coefficient at different temperature and as well as variation of moisture with the time.

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Variable-Mass Thermodynamic Analysis of Drying Process

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C ◽

10.1115/imece2008-67293 ◽

2008 ◽

Author(s):

Yingbai Xie ◽

Hang Su ◽

Xuedong Zhang ◽

Zhouxuan Xu

Keyword(s):

Experimental Data ◽

Heat Pump ◽

Thermodynamic Analysis ◽

Variable Mass ◽

Moisture Removal ◽

Drying Process ◽

Classical Thermodynamic ◽

Complex Process ◽

Heat Pump Drying ◽

Simultaneous Heat

Drying is the complex process which involving simultaneous heat, mass and momentum transfer phenomena. The variable-mass thermodynamic viewpoint is introduced to analysis the drying process. For a closure heat pump drying equipment, variable-mass thermodynamic models based on the first law are constructed. Calculations on the rate of moisture removal and supply airflow are done based on the values of experimental data. The efficiency of drying process is calculated with the variable-mass and the classical thermodynamic method; the two methods have the same result. And the variable-mass thermodynamic analysis reveals that only under the rigorous conditions, drying can be treated as isenthalpic process.

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Moisture Removal from Natural Jute Fibre by Plasma Drying Process

Plasma Chemistry and Plasma Processing ◽

10.1007/s11090-011-9340-1 ◽

2011 ◽

Vol 32 (2) ◽

pp. 249-258 ◽

Cited By ~ 11

Author(s):

M. M. Morshed ◽

M. M. Alam ◽

S. M. Daniels

Keyword(s):

Moisture Removal ◽

Jute Fibre ◽

Drying Process

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Study on the Effect of Salt Modulation upon the Maize Drying Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.430-432.1412 ◽

2012 ◽

Vol 430-432 ◽

pp. 1412-1416 ◽

Cited By ~ 1

Author(s):

Jun Xing Li ◽

Ya Qiu Zhang ◽

Wen Fu Wu ◽

Chun Shan Liu

Keyword(s):

Air Temperature ◽

Removal Rate ◽

Moisture Removal ◽

Drying Method ◽

Drying Process ◽

Moisture Change ◽

Drying Time ◽

Thin Layer Drying ◽

Reasonable Choice ◽

Drying Curve

A maize drying method of salt modulation is presented in this paper. Based on the thin-layer drying experiment [1], the effects of drying air temperature and salt amount on moisture removal rate is analyzed [2], and mathematical model equation is established on relationship between maize moisture ratio and drying time [3]. The experiment result shows that: a reasonable choice of the amount of salt, air temperature and other process parameters is useful to improve drying rate of maize. Salt modulated drying curve is exponentially. The more salt is added in, the faster the moisture removal rate. However, in the case of excessive salt, there may be a critical point of moisture change in the amount of salt until this point the faster the higher the salt amount, whereas the slower; if the critical changing point is higher than the safety moisture point, generally it will conductive to the maize moisture removal process.

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Drying of Sisal Fiber: A Numerical Analysis by Finite-Volumes

Energies ◽

10.3390/en14092514 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2514

Author(s):

Jacqueline F. B. Diniz ◽

João M. P. Q. Delgado ◽

Anderson F. Vilela ◽

Ricardo S. Gomez ◽

Arianne D. Viana ◽

...

Keyword(s):

Relative Humidity ◽

Moisture Content ◽

Sisal Fiber ◽

Moisture Removal ◽

Drying Process ◽

Porous Bed ◽

Bed Porosity ◽

Long Time ◽

Sisal Fibers ◽

Drying Conditions

Vegetable fibers have inspired studies in academia and industry, because of their good characteristics appropriated for many technological applications. Sisal fibers (Agave sisalana variety), when extracted from the leaf, are wet and must be dried to reduce moisture content, minimizing deterioration and degradation for long time. The control of the drying process plays an important role to guarantee maximum quality of the fibers related to mechanical strength and color. In this sense, this research aims to evaluate the drying of sisal fibers in an oven with mechanical air circulation. For this purpose, a transient and 3D mathematical model has been developed to predict moisture removal and heating of a fiber porous bed, and drying experiments were carried out at different drying conditions. The advanced model considers bed porosity, fiber and bed moisture, simultaneous heat and mass transfer, and heat transport due to conduction, convection and evaporation. Simulated drying and heating curves and the hygroscopic equilibrium moisture content of the sisal fibers are presented and compared with the experimental data, and good concordance was obtained. Results of moisture content and temperature distribution within the fiber porous bed are presented and discussed in details. It was observed that the moisture removal and temperature kinetics of the sisal fibers were affected by the temperature and relative humidity of the drying air, being more accentuated at higher temperature and lower relative humidity, and the drying process occurred in a falling rate period.

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