Experimental Investigation of a Lab-Scale, Cross-Flow Grain Dryer for Testing of Drying Efficiency and Characteristic Profiles of a Packed Bed

2015 ◽  
Author(s):  
Taylor N. Suess ◽  
Michael P. Twedt ◽  
Stephen P. Gent
Keyword(s):  
Energy Use ◽  
Cross Flow ◽  
Electric Heating ◽  
Packed Bed ◽  
Operating Conditions ◽  
Heating Process ◽  
Air Temperatures ◽  
Two Factors ◽  
Forced Air ◽  
Drying Efficiency

This study investigates the drying mechanisms of corn when it is exposed to air at elevated temperature and velocity within a cross-flow packed bed dryer. A highly-instrumented laboratory-scale experimental test dryer was constructed to batch-dry samples of 0.03 m3 (1 ft3) of high moisture corn. This is achieved using a perforated wall drying chamber with forced air at temperatures ranging from 180–240°F. The high temperature, high velocity air entering the column is supplied by a variable speed fan and a variable Wattage electric heating coil through a 0.09 m2 (1 ft2) square air duct. This device is able to precisely control the drying air temperate and flow rate, while also measuring the temperature and humidity of the air exiting the dryer. In creating and instrumenting this apparatus, tests were performed to analyze both energy use and drying rate to determine the operating conditions that find a balance between energy and time requirements for moisture removal. This study used a variety of supply air temperatures and air flow rates in drying samples of corn at two initial moisture contents (19%MC and 24%MC) to 15%MC. This is done to determine if there are notable differences in energy requirements (Btu/pound water removed) between different operating conditions. This study determined that corn undergoes a significant pre-heating process before peak drying efficiency is achieved. Current grain dryer designs should focus the most energy just after that pre-heating process for highest overall efficiencies. Additionally, this study found an inverse relationship between dry time and energy efficiency, which showed that an optimum balance between those two factors should be identified.

Experimentally Investigating the Thermal Effects of Cross Flow Corn Drying

2012 ◽  
Author(s):  
Stephen P. Gent ◽  
Michael P. Twedt ◽  
Chad R. Abrahamson
Keyword(s):  
Thermal Effects ◽  
Crop Yields ◽  
Cross Flow ◽  
Packed Bed ◽  
The United States ◽  
Pilot Scale ◽  
High Energy ◽  
Operating Conditions ◽  
Column Height ◽  
Grain Drying

This study measured the thermal effects of corn drying within a continuous cross-flow grain dryer based on a variety of operating conditions. The dryer contains a column of grain that acts as a packed bed in which the air flows through the voids between the kernels. The study analyzed the following parameters and their effects on corn drying: dryer column thickness, air flow rate per volume of corn, air drying temperature, and incoming and outgoing corn moisture. A pilot-scale cross flow corn dryer with variable column thickness, variable drying air temperature, and variable fan speed was used to experimentally dry corn. The pilot scale dryer has a drying column height of 3.35 m (132 in.), column width of 0.61 m (24 in.) and a variable thickness of 0.203 m to 0.305 m (8 to 12 in.). An array of thermocouples was arranged through the packed bed of corn to measure the thermal profile as the air propagated through the corn. The thermal profiles from the experiments were compared and evaluated among the experiments. In the United States, corn is a primary grain commodity. Improved farming practices, in conjunction with improved grain genetics, have resulted in increased grain yields and the ability to grow crops in locations not possible two decades prior. After harvesting, most grains require supplemental drying to prevent spoilage. Continuous flow grain dryers have become a common method of drying and conditioning large amounts of grain. Grain dryers are required to dry grain faster and more efficiently without sacrificing grain quality. However, higher energy costs and increased crop yields have made grain drying the second largest expense for grain producers due to their high energy consumption of propane or natural gas. The overarching goal of this study is to determine the primary factors that influence heat propagation within the packed bed of grain with the intention of incorporating these effects into numerical grain drying models.

Cake Formation in Cross-Flow Microfiltration Systems

1992 ◽  
Vol 25 (10) ◽  
pp. 149-162 ◽  
Author(s):  
V. L. Pillay ◽  
C. A. Buckley
Keyword(s):  
Cross Flow ◽  
Operating Conditions ◽  
Waste Waters ◽  
Domestic Waste ◽  
Time Curve ◽  
Good Correspondence ◽  
Operating Variables ◽  
Start Up ◽  
Turbulent Flow Regime ◽  
Cake Formation

Cross-flow microfiltration (CFMF) has potentially wide application in the processing of industrial and domestic waste waters. Optimum design and operation of CFMF systems necessitates a knowledge of the characteristic system behaviour, and an understanding of the mechanisms governing this behaviour. This paper is a contribution towards the elucidation and understanding of the behaviour of a woven fibre CFMF operated in the turbulent flow regime. The characteristic flux-time curve and effects of operating variables on flux are presented for a limestone suspension cross-flow filtered in a 25 mm woven fibre tube. The phenomena contributing to the shape of the flux-time curve are discussed. A model of the mechanisms governing cake growth and limit is presented. Predicted steady-state fluxes show a notably good correspondence with experimentally measured values. It is also found that the flux may not be uniquely defined by the operating conditions, but may also be a function of the operating path taken to reach the operating point. This is of significance in the start-up and operation of CFMF units.

Cometabolism in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 215-225 ◽  
Author(s):  
Gerald E. Speitel ◽  
Robert L. Segar
Keyword(s):  
Chlorinated Solvents ◽  
Packed Bed ◽  
Operating Conditions ◽  
Mixed Cultures ◽  
Treatment Technology ◽  
Hydraulic Residence Time ◽  
Slow Growth Rate ◽  
Biofilm Reactors ◽  
Aerobic Cometabolism ◽  
Degrading Bacteria

Aerobic cometabolism of chlorinated aliphatic solvents in biofilm reactors is a potential treatment technology for contaminated water and air streams. This research investigated cometabolism by pure and mixed cultures of methanotrophs and mixed cultures of phenol-degrading bacteria. Initial experiments with continuous-flow, packed-bed bioreactors proved unsuccessful; therefore, the major focus of the work was on sequencing biofilm reactors, which cycle between two modes of operation, degradation of chlorinated solvents and rejuvenation of the microbial population. Particular success was obtained with a mixed culture of phenol degraders in the treatment of chlorinated ethenes (e.g., trichloroethylene - TCE). Under the best operating conditions, 90% removal of TCE occurred at a 14-minute packed-bed hydraulic residence time. The bioreactors required only two, 1.5 h biomass rejuvenation periods per day to sustain this removal. Experiments with Methylosinus trichosporium OB3b were less successful because of the organism's slow growth rate, relatively poor ability to attach to surfaces, and its inability to successfully compete with other methanotrophs in the bioreactor environment. Overall, however, the research demonstrated the potential attractiveness of sequencing biofilm reactors in treating water contaminated with chlorinated solvents.

Multilevel cross flow rotating packed bed to enhance gas film control mass transfer process

2021 ◽  
Vol 161 ◽  
pp. 108321
Author(s):  
Qing-Qing Duan ◽  
Zhi-Guo Yuan ◽  
You-Zhi Liu ◽  
Shan-Shan Duan ◽  
Xi-Fan Duan
Keyword(s):  
Mass Transfer ◽  
Transfer Process ◽  
Cross Flow ◽  
Mass Transfer Process ◽  
Packed Bed ◽  
Rotating Packed Bed

Effects of Air Temperature on Combustion Characteristics of LPG Diffusion Flame

2020 ◽  
Vol 1008 ◽  
pp. 128-138
Author(s):  
Ahmed M. Salman ◽  
Ibrahim A. Ibrahim ◽  
Hamada M. Gad ◽  
Tharwat M. Farag
Keyword(s):  
Air Temperature ◽  
Diffusion Flame ◽  
Nitrogen Addition ◽  
Flame Length ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Low Oxygen ◽  
Air Temperatures ◽  
Air Stream ◽  
Wide Range

In the present study, the combustion characteristics of LPG gaseous fuel diffusion flame at elevated air temperatures were experimentally investigated. An experimental test rig was manufactured to examine a wide range of operating conditions. The investigated parameters are the air temperatures of 300, 350, 400, 450, and 500 K with constant percentage of nitrogen addition in combustion air stream of 5 % to give low oxygen concentration of 18.3 % by mass at constant air swirl number, air to fuel mass ratio, and thermal load of 1.5, 30, and 23 kW, respectively. The gaseous combustion characteristics were represented as axial and radial temperatures distributions, temperatures gradient, visible flame length and species concentrations. The results indicated that as the air temperature increased, the chemical reaction rate increased and flame volume decreased, the combustion time reduced leading to a reduction in flame length. The NO concentration reaches its maximum values near the location of the maximum centerline axial temperature. Increasing the combustion air temperature by 200 K, the NO consequently O2 concentrations are increased by about % 355 and 20 % respectively, while CO2 and CO concentrations are decreased by about % 21 and 99 % respectively, at the combustor end.

scholarly journals Data-driven Modelling of Microfiltration Process with Embedded Static Mixer for Steepwater from Corn Starch Industry

2017 ◽  
Author(s):  
Laslo Šereš ◽  
Ljubica Dokić ◽  
Bojana Ikonić ◽  
Dragana Šoronja-Simović ◽  
Miljana Djordjević ◽  
...  
Keyword(s):  
Corn Starch ◽  
Desirability Function ◽  
Specific Energy Consumption ◽  
Cross Flow ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Static Mixer ◽  
Permeate Flux ◽  
Experimental Conditions ◽  
Starch Industry

Cross-flow microfiltration using ceramic tubular membrane was applied for treatment of steepwater from corn starch industry. Experiments are conducted according to the faced centered central composite design at three different transmembrane pressures (1, 2 and 3 bar) and cross-flow velocities (100, 150 and 200 L/h) with and without the usage of Kenics static mixer. For examination of the influence of the selected operating conditions at which usage of the static mixer is justified, a response surface methodology and desirability function approach were used. Obtained results showed improvement in the average permeate flux by using Kenics static mixer for 211 % to 269 % depending on experimental conditions when compared to the system without the static mixer. As a result of optimization, the best results considering flux improvement as well as reduction of specific energy consumption were obtained at low transmembrane pressure and lower feed cross-flow rates.

scholarly journals Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

2016 ◽  
Vol 20 (6) ◽  
pp. 576-580 ◽  
Author(s):  
Cristian F. Costa ◽  
Paulo C. Corrêa ◽  
Jaime D. B. Vanegas ◽  
Fernanda M. Baptestini ◽  
Renata C. Campos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Drying Process ◽  
Drying Temperature ◽  
Air Temperatures ◽  
Nutritional Qualities ◽  
Forced Air ◽  
Air Circulation ◽  
Best Fit

ABSTRACT Jabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba) were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s-1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol-1. Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.

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