Energy Efficiency Study on Two Wisconsin Grain Drying Systems: Mixed Flow and Continuous Cross Flow Grain Dryers

2010 ◽  
Author(s):  
Jennifer L Brinker ◽  
Jennifer L Brinker ◽  
Alex Johnson
Keyword(s):  
Energy Efficiency ◽  
Cross Flow ◽  
Mixed Flow ◽  
Grain Drying

scholarly journals Energy and Exergy Analyses of Tube Banks in Waste Heat Recovery Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2094 ◽  
Author(s):  
Mustafa Erguvan ◽  
David MacPhee
Keyword(s):  
Energy Efficiency ◽  
Reynolds Number ◽  
Heat Recovery ◽  
Waste Heat ◽  
Cross Flow ◽  
Exergy Efficiency ◽  
Circular Cylinders ◽  
Published Data ◽  
Energy And Exergy ◽  
Exergy Analyses

In this study, energy and exergy analyses have been investigated numerically for unsteady cross-flow over heated circular cylinders. Numerous simulations were conducted varying the number of inline tubes, inlet velocity, dimensionless pitch ratios and Reynolds number. Heat leakage into the domain is modeled as a source term. Numerical results compare favorably to published data in terms of Nusselt number and pressure drop. It was found that the energy efficiency varies between 72% and 98% for all cases, and viscous dissipation has a very low effect on the energy efficiency for low Reynolds number cases. The exergy efficiency ranges from 40–64%, and the entropy generation due to heat transfer was found to have a significant effect on exergy efficiency. The results suggest that exergy efficiency can be maximized by choosing specific pitch ratios for various Reynolds numbers. The results could be useful in designing more efficient heat recovery systems, especially for low temperature applications.

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.

scholarly journals Effect of Mixed-Flow Fans with a Newly Shaped Diffuser on Heat Stress of Dairy Cows Based on CFD

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4315 ◽  
Author(s):  
Yao ◽  
Shi ◽  
Zhao ◽  
Ding
Keyword(s):  
Energy Efficiency ◽  
Heat Stress ◽  
Dairy Cows ◽  
Cfd Simulation ◽  
Elevation Angle ◽  
Maximum Flow ◽  
Dynamics Simulation ◽  
Mixed Flow ◽  
Wind Speeds ◽  
Flow Flux

Mixed-flow fans (MFF) are widely used to reduce the heat stress in dairy cows in summer. Our research team developed MFFs with a newly shaped diffuser with the length of 250 mm and the circumferential angle of 150°, which have better performance in terms of maximum flow flux and energy efficiency. However, how the elevation angle of the diffuser influences the performance of MFFs and how the optimal fan perform in the field experiment has not been studied yet. In this paper, the diffuser was optimized by CFD (Computational Fluid Dynamics) simulation of the fan and a laboratory prototype test. An orthogonal test showed no interaction among length, circumferential angle, and elevation angle. The diffuser with an elevation angle of 10° performed better than that with an elevation angle of 0°, showing increased jet lengths, flow flux, and energy efficiency by 0.5 m, 0.69%, and 1.39%, respectively, and attaining greater axial wind speeds and better non-uniformity coefficients at the dairy cattle height. Then, through on-site controlled trials, we found that the 10°/150°/250 mm diffusers increased the overall average wind speeds by 9.4% with respect to the MFFs without a diffuser. MFFs with the newly shaped diffuser were used for field tests, and their effectiveness in alleviating heat stress in dairy cows was evaluated by testing environmental parameters and dairy cows’ physiological indicators. Although the temperature–humidity indexes (THIs) in the experimental barn with the optimized fan at different times were lower than those in the controlled barn, the environmental conditions corresponded to moderate heat stress. However, this was not consistent with cow's respiratory rate and rectal temperature. Finally, on the basis of the CFD simulation of a dairy cow barn, the equivalent temperature of cattle (ETIC), which takes into account the effect of air velocity, showed that the environment caused moderate heat stress only at 13:00, but not at other times of the day. This shows that ETIC is more accurate to evaluate heat stress.

scholarly journals Parameters Online Detection and Model Predictive Control during the Grain Drying Process

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Lihui Zhang ◽  
Helei Cui ◽  
Hongli Li ◽  
Feng Han ◽  
Yaqiu Zhang ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Constant Velocity ◽  
Variable Temperature ◽  
Structural Characteristics ◽  
Cross Flow ◽  
System Control ◽  
Drying Process ◽  
Grain Drying ◽  
Set Up

In order to improve the grain drying quality and automation level, combined with the structural characteristics of the cross-flow circulation grain dryer designed and developed by us, the temperature, moisture, and other parameters measuring sensors were placed on the dryer, to achieve online automatic detection of process parameters during the grain drying process. A drying model predictive control system was set up. A grain dry predictive control model at constant velocity and variable temperature was established, in which the entire process was dried at constant velocity (i.e., precipitation rate per hour is a constant) and variable temperature. Combining PC with PLC, and based on LabVIEW, a system control platform was designed.

Energetic and exergetic investigation of a mixed flow dryer: A case study of maize grain drying

2020 ◽  
pp. 1-15 ◽  
Author(s):  
Md. Hasan Tarek Mondal ◽  
Md. Ayub Hossain ◽  
Md. Abdul Momin Sheikh ◽  
Md. Akhtaruzzaman ◽  
Md. Sazzat Hossain Sarker
Keyword(s):  
Mixed Flow ◽  
Grain Drying ◽  
Maize Grain

Modeling of grain drying in continuous cross-flow sliding bed dryers

1996 ◽  
Vol 74 (5) ◽  
pp. 797-805 ◽  
Author(s):  
S. Miguel A. Mayta ◽  
Giulio Massarani ◽  
José Carlos Pinto
Keyword(s):  
Cross Flow ◽  
Grain Drying

Optimization of mixed flow dryers to increase energy efficiency

2017 ◽  
Vol 35 (8) ◽  
pp. 985-993 ◽  
Author(s):  
F. Weigler ◽  
H. Scaar ◽  
G. Franke ◽  
J. Mellmann
Keyword(s):  
Energy Efficiency ◽  
Mixed Flow ◽  
Increase Energy Efficiency

Turbulence-Induced Vibration of Tube Bundle in Cross and Parallel Jet Mixed Flow

1989 ◽  
Vol 111 (4) ◽  
pp. 352-360 ◽  
Author(s):  
K. Kawamura ◽  
A. Yasuo
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Field ◽  
Tube Bundle ◽  
Cross Flow ◽  
Jet Flow ◽  
Fretting Wear ◽  
Baffle Plate ◽  
Mixed Flow ◽  
The Cross

In the multi-tube type of heat exchanger, baffle plates are located at appropriate intervals to support the heat transfer tubes. Depending on the baffle plate type employed, the flow field in the tube bundle will consist of a mixture of the cross flow (the fluid flows at right angles to the tube bundle along the baffle plate surfaces) and the parallel jet flow (the fluid streams through channels such as the flow holes of the baffle plates in the form of jets and flows in parallel with the tube bundle). Vibrations induced by the flow can cause fretting wear and fatigue of the heat transfer tubes. Therefore, it it essential to establish a method of evaluating heat transfer tube vibrations induced by the mixed flow for the purpose of evaluating the integrity of heat exchanger tubes. In this paper, three different flows, that is, cross, parallel jet and mixed flows, were simulated in order to clarify the relationships between the flow conditions and vibration of the tube bundle, and to study a method for evaluating tube bundle vibrations induced by turbulence in the mixed flow field by using the vibration characteristics in the cross flow field and the parallel jet flow field.

A Numerical Case Study: Effect of Heat Leakage on Thermodynamic Efficiency of Cylinders in Cross-Flow

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Mustafa Erguvan ◽  
David W. MacPhee
Keyword(s):  
Energy Efficiency ◽  
Reynolds Number ◽  
Cross Flow ◽  
Exergy Efficiency ◽  
Thermodynamic Efficiency ◽  
Inlet Temperature ◽  
Heat Leakage ◽  
Lower Reynolds Number ◽  
Energy And Exergy ◽  
Artificial Heat

Numerical and thermodynamic analyses have been undertaken in this study to examine energy and exergy efficiencies of in-line tube banks for unsteady cross-flow. Pitch ratio (PR) and the number of in-line tubes are varied for Reynolds numbers of 500 and 10,000, and artificial heat leakages are modeled as a source term. Numerical results are compared with published values, and good agreements are obtained regarding Nusselt number and pressure drop. Whereas the energy efficiency varied between 72% and 99%, the exergy efficiency ranged from 40% to 70%. It was found that while viscous dissipation has a low effect on energy and exergy efficiencies for the lower Reynolds number, it has a significant effect for the higher Reynolds number. On the other hand, heat leakage had a greater effect on exergy efficiency compared to energy efficiency, especially for the lower Reynolds number case. Overall, this study verified how heat leakage could play a vital role on efficiency for low-inlet temperature heat recovery systems.

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