Comprehensive Analysis of Grain Dryer Types for Corn Farming Operations

Published by The Grain Handling Direct Team - Powered by AI on Apr 25th 2025

This comprehensive analysis examines the strengths and weaknesses of four major grain dryer types: mixed flow dryers, portable grain dryers, in-bin drying systems, and tower dryers. The analysis focuses specifically on their suitability for corn farming operations in the Upper Midwest climate of the United States and Canada, with particular emphasis on energy efficiency, cost considerations, and maintenance requirements.

Each dryer type offers distinct advantages and disadvantages, with their optimal application varying based on operation size, financial considerations, existing infrastructure, management style, and local support availability. This document provides corn farmers with the information needed to make informed decisions about which grain drying system provides the best value for their specific operations.

Introduction and Methodology

This analysis was conducted through extensive research of technical specifications, manufacturer information, agricultural extension publications, and real-world user experiences. The research methodology included:

Detailed examination of operational principles for each dryer type
Analysis of energy efficiency factors and performance metrics
Evaluation of initial investment and operating costs
Assessment of maintenance requirements and brand performance differences
Collection of user feedback from farming forums and social media
Comparative analysis across multiple factors relevant to corn farming in the Upper Midwest

The findings are presented in a structured format that allows for direct comparison between dryer types while acknowledging that the "best" solution depends on the specific circumstances of each farming operation.

Decision Framework for Farmers

When selecting a grain dryer, farmers should consider the following factors:

Operation Size

Small operations (<50,000 bushels annually): Consider portable dryers or in-bin systems
Medium operations (50,000-150,000 bushels): Consider mixed flow dryers, Shivvers systems, or multiple in-bin systems
Large operations (>150,000 bushels): Consider tower dryers or multiple mixed flow dryers

Financial Considerations

Limited capital: Portable dryers or conventional in-bin systems offer lowest initial investment
Focus on operating costs: In-bin systems (conventional or Shivvers) offer lowest long-term operating costs
Return on investment: Consider service life and resale value; mixed flow and tower dryers typically maintain value better

Existing Infrastructure

Limited electrical service: Portable dryers may be preferable as they often require less electrical capacity
Existing bins: Adding in-bin drying capability to existing storage may be cost-effective
Limited space: Tower dryers offer maximum capacity in minimal footprint

Management Style

Hands-on operators: May prefer the simplicity of portable or in-bin systems
Technology-focused: May prefer the automation of mixed flow, Shivvers, or tower dryers
Risk-averse: May prefer the weather independence of high-capacity systems like tower or mixed flow dryers

Local Support

Dealer proximity: Consider local dealer support for parts and service
Brand prevalence: More common brands in the region typically have better parts availability
Service technicians: Availability of qualified service technicians for more complex systems

Dryer Type 1: Mixed Flow Grain Dryers

General Principles and Operation

Mixed flow dryers represent a significant advancement in grain drying technology, combining elements of cross-flow and concurrent-flow designs. In these systems, grain flows vertically downward through the dryer while air moves both horizontally and vertically through the grain column in a mixed-flow pattern.

The key operational components include:

A series of alternating air supply and exhaust ducts arranged in a pattern that creates a mixed airflow
Grain columns typically 12-16 inches thick for optimal air penetration
Metering rolls at the bottom to control grain flow rate
Multiple heating zones with independent temperature control
Cooling section in the lower portion of many models

The mixed airflow pattern ensures that each kernel receives multiple exposures to the drying air, resulting in more uniform moisture removal and reduced thermal stress on the grain. This design allows for higher drying temperatures without compromising grain quality, as the exposure time to peak temperatures is reduced compared to other dryer types.

Energy Efficiency Factors

Mixed flow dryers achieve their efficiency through several design elements:

Multiple air passes: The mixed flow pattern allows drying air to make multiple passes through the grain, extracting more moisture per unit of energy.
Heat recovery systems: Many modern mixed flow dryers incorporate heat recovery, capturing and reusing heat from the cooling section.
Precise temperature control: Multiple heating zones allow for optimized temperature profiles that maximize efficiency.
Improved airflow dynamics: The mixed flow pattern reduces static pressure requirements, lowering fan energy consumption.

According to manufacturer data and field studies, mixed flow dryers typically use 1,600-2,200 BTU per pound of water removed, representing a 15-25% improvement over conventional cross-flow designs.

Cost Considerations

Initial Investment

Small to medium capacity (500-1,000 bu/hr): $75,000-$200,000
Medium to large capacity (1,000-3,000 bu/hr): $200,000-$400,000
Large capacity (3,000+ bu/hr): $400,000-$500,000+

These costs typically include the dryer unit itself but may not include site preparation, electrical work, or grain handling equipment.

Operating Costs

Fuel (propane): $0.015-0.025 per bushel per point of moisture removed
Electricity: $0.005-0.010 per bushel per point of moisture removed
Maintenance: Approximately 2-3% of initial investment annually
Labor: Minimal due to automation, typically 0.5-1 hour per day of operation

For a typical corn farming operation in the Upper Midwest removing 10 points of moisture, total operating costs range from $0.20-$0.35 per bushel.

Maintenance Requirements

Mixed flow dryers require regular maintenance to ensure optimal performance:

Pre-season Maintenance

Inspection and cleaning of all air ducts and screens
Checking and calibration of temperature sensors
Lubrication of all bearings and moving parts
Inspection of burners and gas trains
Testing of safety systems and controls

In-season Maintenance

Daily inspection of screens for debris or blockages
Weekly checking of drive components and bearings
Regular monitoring of fuel efficiency and adjusting as needed
Periodic cleaning of sensors and control components

Post-season Maintenance

Thorough cleaning of all components
Inspection for wear and replacement of worn parts
Weatherproofing for winter conditions
Documentation of any issues for off-season repair

The modular design of most mixed flow dryers facilitates maintenance, with accessible service points and replaceable components. However, the complexity of these systems requires more technical knowledge than simpler dryer types.

Brand Performance Differences

Several manufacturers produce mixed flow dryers with notable differences:

AGI (Neco) Mixed Flow Dryers

Energy efficiency 25-30% better than conventional dryers
Modular design allows for capacity expansion
Lower profile design reduces structural requirements
Variable frequency drives on fans for energy savings
Competitive pricing but smaller dealer network

Suitability for Upper Midwest Climate

Mixed flow dryers are well-suited to the Upper Midwest climate for several reasons:

Weather adaptability: Can operate effectively in the cooler fall conditions typical of the region
Moisture handling capability: Efficiently processes the higher moisture corn often harvested in the region
Energy efficiency: Important in a region with significant temperature variations and potentially high energy costs
Drying capacity: Maintains throughput even as ambient temperatures drop during harvest

For corn farming operations in the Upper Midwest, mixed flow dryers offer a good balance of capacity, grain quality, and energy efficiency, particularly for medium to large operations.

Advantages and Disadvantages for Corn Drying

Advantages

Superior grain quality with minimal stress cracks
Excellent energy efficiency compared to conventional dryers
Consistent performance across varying weather conditions
High capacity in a relatively compact footprint
Advanced automation and monitoring capabilities
Good resale value and long service life

Disadvantages

Higher initial investment than portable or in-bin systems
More complex maintenance requirements
Requires proper wet holding and dry storage capacity
Less energy efficient than in-bin systems
Requires three-phase power in most cases
Less suitable for very small operations

Dryer Type 2: Portable Grain Dryers

General Principles and Operation

Portable grain dryers are self-contained units designed for mobility and flexibility. They typically operate as batch dryers, though some models offer continuous flow capability. The basic operational principles include:

A cylindrical or rectangular drying chamber with perforated walls
Propane or natural gas burners with direct or indirect heating
Axial or centrifugal fans to move air through the grain mass
Loading and unloading systems (often built-in augers)
Control systems ranging from basic manual controls to advanced automation
Trailer mounting for transportation between sites

The operation typically follows a batch cycle:

Loading grain into the drying chamber
Heating and drying to target moisture
Cooling the grain (in some models)
Unloading the dried grain

Some advanced portable dryers offer continuous flow operation, where grain is continuously loaded at the top and discharged at the bottom after passing through heating and cooling zones.

Energy Efficiency Factors

Portable grain dryers generally have lower energy efficiency than other dryer types due to:

Single-pass airflow: Most portable dryers use a single pass of air through the grain, limiting moisture extraction per unit of energy.
Heat loss: The portable nature and typically smaller size result in greater surface area relative to volume, increasing heat loss.
Batch operation: The heating and cooling cycles of batch operation reduce overall efficiency compared to continuous flow systems.
Limited heat recovery: Few portable systems incorporate heat recovery technology.

Typical energy usage ranges from 1,800-2,500 BTU per pound of water removed, approximately 10-25% less efficient than mixed flow or tower dryers.

Cost Considerations

Initial Investment

Small capacity (100-300 bu/hr): $20,000-$50,000
Medium capacity (300-600 bu/hr): $50,000-$100,000
Large capacity (600-1,200 bu/hr): $100,000-$150,000

The lower initial investment makes portable dryers attractive for smaller operations or as supplementary capacity.

Operating Costs

Fuel (propane): $0.018-0.030 per bushel per point of moisture removed
Electricity: $0.003-0.008 per bushel per point of moisture removed
Maintenance: Approximately 3-5% of initial investment annually
Labor: Moderate, typically 1-2 hours per day of operation

For a typical corn farming operation in the Upper Midwest removing 10 points of moisture, total operating costs range from $0.25-$0.40 per bushel.

Maintenance Requirements

Portable grain dryers have relatively straightforward maintenance needs:

Pre-season Maintenance

Inspection of burners and fuel systems
Checking electrical components and controls
Lubrication of augers and moving parts
Inspection of screens and perforated surfaces
Testing of safety systems

In-season Maintenance

Regular cleaning of screens and perforations
Monitoring of fuel efficiency
Checking drive components and bearings
Inspection of loading and unloading mechanisms

Post-season Maintenance

Thorough cleaning of all components
Weatherproofing for storage
Inspection of trailer components if mobile
Fuel system winterization

The simpler design of portable dryers generally makes maintenance less technical, though the batch operation can mean more frequent attention to loading and unloading systems.

Brand Performance Differences

Several manufacturers produce portable grain dryers with notable differences:

Farm Fans

Long-established brand with wide dealer network
Models range from basic to highly automated
Mixed reliability reviews, particularly for electrical components
Good grain quality but less uniform than mixed flow systems
Competitive pricing and good parts availability

GSI Portable Dryers

WatchDog remote monitoring capabilities
Integration with other GSI grain handling equipment
Higher noise levels reported by some users
Strong dealer support in many regions
Higher initial cost but good resale value

Superb Portable Dryers

Known for quieter operation
Fuel-efficient designs
Strong dealer support in certain regions
Good performance in colder conditions
Competitive pricing with good warranty coverage

Suitability for Upper Midwest Climate

Portable grain dryers have mixed suitability for the Upper Midwest climate:

Strengths for the Region

Can be moved to different locations as needed
Lower initial investment for smaller operations
Can serve as supplementary capacity during challenging harvest conditions
Simple operation in remote locations

Challenges for the Region

Less efficient in colder temperatures
Limited capacity may struggle with high-moisture corn common in the region
Batch operation can slow harvest pace in short weather windows
Higher per-bushel operating costs in a region with potentially high energy prices

For corn farming operations in the Upper Midwest, portable dryers are best suited for smaller operations (under 50,000 bushels annually) or as supplementary capacity for larger operations.

Advantages and Disadvantages for Corn Drying

Advantages

Lowest initial investment of all dryer types
Mobility between locations
Simplicity of operation
Minimal site preparation required
Good option for smaller operations or backup capacity
Flexibility for diversified operations

Disadvantages

Limited capacity for larger operations
Higher labor requirements
Less energy efficient, especially in cold weather
Batch operation can slow harvest pace
Generally shorter service life
Higher per-bushel operating costs

Dryer Type 3: In-Bin Drying Systems

General Principles and Operation

In-bin drying systems use bins equipped with perforated floors and fans to dry grain in the same structure where it will be stored. These systems typically operate using one of two primary methods:

Natural-air drying (also called ambient-air drying) - Uses unheated outdoor air to dry corn to a safe storage moisture through a slow process that relies on the natural drying potential of ambient air.
Low-temperature drying - Similar to natural-air drying but adds a small amount of supplemental heat (typically 5-10°F above ambient) to improve drying capacity and reduce relative humidity.

The basic components include:

A bin with a fully perforated floor
One or more fans to move air through the grain
A grain spreader to distribute grain evenly
Exhaust vents in the roof to allow moist air to escape
Optional heaters for supplemental heat
Optional grain stirrers in some applications

The drying process works as follows:

The bin is filled with grain, typically in layers or completely
Air is forced upward through the grain mass, creating a drying zone
This drying zone slowly moves up through the bin
The fan runs continuously until the drying front has moved through the entire grain mass

Shivvers In-Bin Drying Systems

Shivvers Manufacturing offers specialized Counter-Flow grain drying systems that differ significantly from conventional in-bin drying approaches. Their systems are designed to provide more precise control and efficiency while maintaining the quality benefits of in-bin drying.

Unique Counter-Flow Technology

Unlike traditional in-bin systems where air moves upward through a static grain mass, Shivvers systems utilize a counter-flow approach:

Grain Flow Direction - Grain flows downward through the bin in a controlled manner
Air Flow Direction - Heated drying air flows upward, creating the counter-flow effect
Continuous Process - Rather than batch drying, the system can operate continuously

This counter-flow principle creates several advantages:

More efficient moisture removal
More consistent final moisture content
Better energy utilization
Faster drying compared to conventional in-bin systems

System Components

The Shivvers System integrates into new or existing grain bins, transforming the entire bin into a comprehensive drying system with six main components:

Grain Spreader - Facilitates true, level grain loading into the drying bin
Core Machine - Controls grain flow throughout the drying process, ensuring even and consistent drying
Command Center - Computerized control unit that automatically manages the drying process based on operator specifications
Raised Drying Floor - Elevates the grain floor, creating a plenum for the drying system with strategically designed perforations for maximum air flow
Fan/Heater Combination - Provides the heat source and air movement force for the drying process
Transfer Augers - Transport dried grain from the drying bin to storage bin(s)

Shivvers Product Lines

Shivvers offers multiple system configurations to meet different operational needs:

Circu-Lator Performance Systems

Designed for operators seeking maximum drying precision and system flexibility
Incorporates a center vertical auger to move grain up through the center of the bin
Provides three distinct benefits:
- Ability to transform the drying bin into a storage bin by recirculating dried grain
- Comprehensive grain management without additional transfer equipment
- Added drying precision through grain recirculation options

Dri-Flo Performance Systems

Designed for operators with existing grain transfer systems
Focuses on Shivvers Counter-Flow drying precision
Offers maximized removal capacities (up to 2,500 bushels per hour)
Ideal for integration with existing grain handling infrastructure

Automation and Control

A distinguishing feature of Shivvers systems is their advanced automation through the Compu-Dry Command Center:

Fully automated, unattended control of grain drying operations
Computer precision for moisture and temperature management
Remote monitoring capabilities
Automatic adjustment to changing weather conditions
Programmable drying parameters for different grain types and conditions

Cost and Efficiency Considerations

While Shivvers systems typically require a higher initial investment than conventional in-bin systems, they offer several economic advantages:

Energy Efficiency - The counter-flow design optimizes energy usage, with reported fuel savings of 30-40% compared to conventional high-temperature dryers
Labor Savings - Automated operation reduces labor requirements
Throughput - Higher capacity than conventional in-bin systems, though still lower than high-capacity tower dryers
Dual-Purpose Use - Systems can be used for both drying and storage, maximizing infrastructure investment

Maintenance Requirements

Maintenance for Shivvers systems is more involved than conventional in-bin systems but less intensive than high-temperature continuous flow dryers:

Regular inspection of mechanical components (core machine, augers)
Calibration of moisture sensors and control systems
Standard fan and heater maintenance
Floor cleaning and inspection

User Feedback

Farmer feedback on Shivvers systems has been generally positive, particularly regarding:

Grain quality preservation
Energy efficiency
Automation capabilities
Versatility for different grain types

Comparison to Conventional In-Bin Systems

Compared to conventional in-bin drying systems, Shivvers offers:

Advantages:

Faster drying times
More precise moisture control
Higher throughput capacity
Better automation
Less weather dependency

Disadvantages:

Higher initial investment
More complex mechanical systems
Higher maintenance requirements
Requires more technical knowledge to operate optimally

Energy Efficiency Factors

In-bin drying systems are generally the most energy-efficient grain drying method for several reasons:

No direct heating costs (for natural-air systems) - Natural-air drying relies solely on the drying potential of ambient air, eliminating fuel costs associated with heating air.
Lower electrical usage per bushel - While in-bin systems run fans for longer periods, the total energy consumption per bushel is typically lower than high-temperature systems.
Optimal use of ambient conditions - These systems take advantage of the natural drying potential of air, particularly effective in the fall conditions of the Upper Midwest.
Supplemental heat efficiency - When supplemental heat is used, it's typically much more efficient than high-temperature drying because the temperature rise is small (usually just 5-10°F).

According to Iowa State University Extension, natural-air drying systems use approximately 0.33 kWh per point of moisture removed per bushel, making them the most energy-efficient option for corn drying in most scenarios.

Cost Considerations

Initial Investment

Bin with perforated floor: $2-4 per bushel of capacity (varies by size)
Fans and motors: $0.50-1.50 per bushel depending on airflow requirements
Optional equipment (spreaders, stirrers, heaters): $0.25-1.00 per bushel
Shivvers Counter-Flow systems: $3-6 per bushel of capacity (higher than conventional in-bin systems)

Operating Costs

Electricity: Primary operating cost for conventional systems, typically $0.01-0.03 per bushel per point of moisture removed
Propane (for supplemental heat or Shivvers systems): $0.01-0.02 per bushel per point
Maintenance: Relatively low, estimated at 3% of initial investment annually
Labor: Minimal compared to other drying methods, primarily for monitoring

According to Purdue University Extension, the total cost of in-bin drying (including depreciation, interest, repairs, and energy) is typically 30-50% lower than high-temperature drying systems on a per-bushel basis, though drying takes significantly longer.

Maintenance Requirements

In-bin drying systems have relatively low maintenance requirements compared to other grain dryer types:

Pre-season maintenance:
- Inspect and clean perforated floors
- Check fan blades and motors
- Inspect and clean roof vents
- Check electrical connections and controls
- Inspect bin structure for any damage or leaks
In-season maintenance:
- Monitor grain condition regularly
- Check airflow patterns and distribution
- Ensure roof vents remain unobstructed
Post-season maintenance:
- Clean bin thoroughly
- Perform any needed repairs
- Cover fan openings to prevent pest entry

The simplicity of conventional in-bin systems, with fewer moving parts than portable or mixed-flow dryers, contributes to their lower maintenance requirements and generally longer service life. Shivvers systems require additional maintenance for their mechanical components but still generally less than high-temperature dryers.

Brand Performance Differences

Several manufacturers produce in-bin drying equipment with some notable differences:

GSI (Grain Systems Inc.)

Offers Z-Series™ fans with higher efficiency ratings
Provides integrated control systems for managing multiple bins
Features proprietary GrainViz™ technology for moisture monitoring

Brock Grain Systems

Provides GUARDIAN® Series fans with sealed bearings for longer life
Features TRI-CORR® aeration floors with higher structural strength
Offers integrated moisture monitoring systems

Shivvers Manufacturing

Specializes in Counter-Flow drying technology
Offers advanced Compu-Dry Command Center automation
Provides complete system integration from a single manufacturer
Known for excellent grain quality and energy efficiency
Higher initial investment but potentially faster ROI through energy savings

Farmer feedback generally indicates that while there are performance differences between brands, local dealer support, parts availability, and service are often more important factors in brand selection for in-bin drying systems.

Suitability for Upper Midwest Climate

In-bin drying systems are particularly well-suited for the Upper Midwest climate for several reasons:

Ideal ambient conditions - According to the University of Minnesota Extension, "The process works best under cool (40 to 60 degrees Fahrenheit), dry (55 to 75 percent relative humidity) conditions. Since average fall temperature and humidity are in these ranges in the Upper Midwest, natural-air drying usually works quite well."
Energy efficiency in cooler climates - The natural air in the Upper Midwest during harvest season often has good drying potential without requiring supplemental heat.
Longer harvest windows - The ability to harvest at higher moisture contents and dry slowly can be advantageous in the Upper Midwest where harvest windows may be limited by weather.
Lower operating costs - With rising propane and natural gas prices, the electricity-only operation of natural-air systems can be particularly economical in the region.

For corn farming operations in the Upper Midwest, in-bin drying systems offer a balance of energy efficiency and effectiveness, though they require more management attention and longer drying times than high-temperature systems. Shivvers Counter-Flow systems offer a middle ground, providing faster drying than conventional in-bin systems while maintaining better energy efficiency than high-temperature dryers.

Advantages and Disadvantages for Corn Drying

Advantages

Energy efficiency - Uses 30-50% less energy per bushel compared to high-temperature drying
Better grain quality - Slower drying produces fewer stress cracks and less breakage
Lower initial investment - Especially when the bin will also be used for storage
Simpler operation - Fewer moving parts and less complex controls (conventional systems)
Dual-purpose infrastructure - Same structure used for both drying and storage
Better for seed corn - Maintains higher germination rates due to gentler drying
Lower labor requirements - Less handling of grain and less continuous supervision

Disadvantages

Slower drying speed - Can take weeks rather than hours or days (conventional systems)
Weather dependency - Performance varies with ambient conditions (less issue with Shivvers systems)
Management intensive - Requires careful monitoring of grain condition
Limited capacity - Cannot dry large volumes quickly during harvest (conventional systems)
Moisture variability - Can result in less uniform moisture content (conventional systems)
Bin space limitations - Drying depths are limited (typically 16-20 feet maximum)
Higher risk of spoilage - If not managed properly, slow drying can lead to mold growth

Dryer Type 4: Tower Dryers

General Principles and Operation

Tower dryers are vertical, continuous-flow drying systems that use a columnar design to maximize capacity while minimizing footprint. The basic operational principles include:

A tall, cylindrical structure with concentric drying chambers
Grain flows downward through the dryer by gravity
Multiple heating and cooling zones
Internal grain columns typically 12-18 inches thick
Metering systems at the bottom to control grain flow rate
Heat recovery systems in many models

The operation follows these steps:

Wet grain is loaded at the top of the tower
Grain flows downward through heating zones where hot air is forced through the grain column
Dried grain continues downward through cooling zones
Dried and cooled grain is discharged at the bottom

Most tower dryers use a cross-flow design where air moves horizontally through the vertical grain columns, though some newer models incorporate mixed-flow principles for improved efficiency.

Energy Efficiency Factors

Tower dryers achieve energy efficiency through several design elements:

Heat recovery systems - Many tower dryers recapture and reuse heat from the cooling section, reducing overall energy consumption by 15-30%.
Vacuum cooling - Some models use negative pressure to pull ambient air through hot grain for cooling, capturing heat in the process.
Grain column thickness optimization - The grain column thickness is engineered to balance airflow resistance with drying efficiency.
Variable frequency drives - Modern tower dryers often incorporate VFDs on fans to optimize airflow and reduce electrical consumption.

Typical energy usage ranges from 1,400-1,800 BTU per pound of water removed, making tower dryers generally more efficient than portable dryers but less efficient than in-bin systems.

Cost Considerations

Initial Investment

Small to medium capacity (1,000-2,000 bu/hr): $150,000-$400,000
Medium to large capacity (2,000-5,000 bu/hr): $400,000-$700,000
Large capacity (5,000+ bu/hr): $700,000-$1,000,000+

These costs typically include the dryer unit itself but may not include site preparation, electrical work, or grain handling equipment.

Operating Costs

Fuel (propane): $0.014-0.022 per bushel per point of moisture removed
Electricity: $0.004-0.008 per bushel per point of moisture removed
Maintenance: Approximately 2-4% of initial investment annually
Labor: Minimal due to automation, typically 0.5-1 hour per day of operation

For a typical corn farming operation in the Upper Midwest removing 10 points of moisture, total operating costs range from $0.18-$0.30 per bushel.

Maintenance Requirements

Tower dryers require regular maintenance to ensure optimal performance:

Pre-season Maintenance

Inspection and cleaning of all air ducts and screens
Checking and calibration of temperature sensors
Lubrication of all bearings and moving parts
Inspection of burners and gas trains
Testing of safety systems and controls
Inspection of grain metering systems

In-season Maintenance

Daily inspection of screens for debris or blockages
Weekly checking of drive components and bearings
Regular monitoring of fuel efficiency and adjusting as needed
Periodic cleaning of sensors and control components

Post-season Maintenance

Thorough cleaning of all components
Inspection for wear and replacement of worn parts
Weatherproofing for winter conditions
Documentation of any issues for off-season repair

The vertical design of tower dryers can make some maintenance tasks more challenging, often requiring specialized equipment or personnel for accessing upper components.

Brand Performance Differences

Several manufacturers produce tower dryers with notable differences:

GSI Tower Dryers

QuadraTouch Pro™ control systems with advanced monitoring
Proprietary heat recovery systems
Vacuum cooling technology in some models
Strong dealer network in the Upper Midwest
Higher initial cost but strong resale value

Brock Tower Dryers

GUARDIAN® Series with advanced safety features
Unique airflow patterns for improved efficiency
Robust construction with heavy-duty components
Established dealer network
Mid-range pricing with good parts availability

Suitability for Upper Midwest Climate

Tower dryers are well-suited to the Upper Midwest climate for several reasons:

Weather resilience - Can operate effectively in the cooler fall conditions typical of the region
High capacity - Can handle large volumes of grain quickly, important in regions with limited harvest windows
Consistent performance - Less affected by ambient conditions than in-bin or portable systems
Energy recovery systems - Important in a region with potentially high energy costs

For corn farming operations in the Upper Midwest, tower dryers offer excellent capacity and consistent performance, particularly for large operations (over 150,000 bushels annually).

Advantages and Disadvantages for Corn Drying

Advantages

Highest capacity in a small footprint
Consistent performance regardless of weather conditions
Good energy efficiency with heat recovery systems
Excellent automation and monitoring capabilities
Minimal labor requirements
Long service life (typically 25-35 years)

Disadvantages

Highest initial investment of all dryer types
Requires substantial supporting infrastructure (wet holding, dry storage)
Less energy efficient than in-bin systems
More complex maintenance requirements
Requires three-phase power
Less suitable for smaller operations

Comparative Analysis

Energy Efficiency Comparison

Energy efficiency is typically measured in BTU per pound of water removed or fuel usage per bushel per point of moisture removed:

Dryer Type	BTU/lb Water Removed	Propane (gal/bu/point)	Electricity (kWh/bu/point)
Mixed Flow	1,600-2,200	0.015-0.025	0.005-0.010
Portable	1,800-2,500	0.018-0.030	0.003-0.008
In-Bin	1,000-1,500	0.000-0.015*	0.010-0.015
Shivvers	1,400-1,800	0.014-0.020	0.008-0.012
Tower	1,400-1,800	0.014-0.022	0.004-0.008

*Natural-air systems use no propane; low-temperature systems use minimal amounts

In-bin drying systems are generally the most energy-efficient, followed by tower dryers and mixed flow dryers, with portable dryers typically being the least efficient. However, the trade-off is drying speed, with in-bin systems taking significantly longer than the other types.

Initial Investment Comparison

Initial investment varies significantly by dryer type and capacity:

Dryer Type	Small Operation (<50k bu/yr)	Medium Operation (50-150k bu/yr)	Large Operation (>150k bu/yr)
Mixed Flow	$75,000-$200,000	$200,000-$400,000	$400,000-$500,000+
Portable	$20,000-$50,000	$50,000-$100,000	$100,000-$150,000
In-Bin	$30,000-$100,000	$100,000-$200,000	$200,000+
Shivvers	$50,000-$150,000	$150,000-$300,000	$300,000+
Tower	$150,000-$400,000	$400,000-$700,000	$700,000-$1,000,000+

Portable dryers offer the lowest initial investment, followed by conventional in-bin systems, Shivvers systems, mixed flow dryers, and tower dryers. However, when considering the dual-purpose nature of in-bin systems (drying and storage), their effective cost may be lower.

Capacity Comparison

Drying capacity varies significantly by dryer type:

Dryer Type	Typical Capacity Range (bu/hr)	Capacity per $ Invested
Mixed Flow	500-5,000	Medium
Portable	100-1,200	High
In-Bin	100-1,000*	Low
Shivvers	500-2,500	Medium
Tower	1,000-10,000	Medium

*In-bin capacity is highly dependent on ambient conditions and moisture removal required

Tower dryers offer the highest absolute capacity, followed by mixed flow dryers, Shivvers systems, portable dryers, and conventional in-bin systems. However, when considering capacity per dollar invested, portable dryers often provide the highest throughput relative to investment.

Grain Quality Comparison

Grain quality is affected by drying method, with gentler drying generally producing better quality:

Dryer Type	Stress Cracks	Breakage	Test Weight	Overall Quality
Mixed Flow	Low	Low	Excellent	Excellent
Portable	Moderate	Moderate	Good	Good
In-Bin	Very Low	Very Low	Excellent	Excellent
Shivvers	Low	Low	Excellent	Excellent
Tower	Low-Moderate	Low	Very Good	Very Good

In-bin systems (both conventional and Shivvers) and mixed flow dryers generally produce the highest quality grain with minimal stress cracks and breakage, followed by tower dryers and portable dryers.

Maintenance and Labor Requirements

Maintenance and labor needs vary by dryer type:

Dryer Type	Maintenance Complexity	Annual Maintenance Cost	Labor Hours per Day	Technical Knowledge Required
Mixed Flow	Moderate-High	2-3% of investment	0.5-1	Moderate-High
Portable	Low-Moderate	3-5% of investment	1-2	Low-Moderate
In-Bin	Low	2-3% of investment	0.5-1	Low-Moderate
Shivvers	Moderate	3-4% of investment	0.5-1	Moderate
Tower	Moderate-High	2-4% of investment	0.5-1	Moderate-High

Conventional in-bin systems generally have the lowest maintenance requirements and technical knowledge needed, followed by portable dryers, Shivvers systems, mixed flow dryers, and tower dryers.

Operation Size Suitability

Different dryer types are better suited to different operation sizes:

Dryer Type	Small Operations (<50k bu/yr)	Medium Operations (50-150k bu/yr)	Large Operations (>150k bu/yr)
Mixed Flow	Poor-Fair	Excellent	Good
Portable	Excellent	Fair	Poor
In-Bin	Excellent	Good	Fair
Shivvers	Good	Excellent	Fair
Tower	Poor	Good	Excellent

Portable dryers and conventional in-bin systems are most suitable for smaller operations, mixed flow dryers and Shivvers systems for medium-sized operations, and tower dryers for large operations.

Conclusion

There is no single "best" grain dryer for all corn farming operations. The optimal choice depends on the specific circumstances of each operation, including size, financial considerations, existing infrastructure, management style, and local support availability.

For energy efficiency and grain quality, in-bin systems (both conventional and Shivvers) generally excel. For capacity and weather independence, tower dryers are typically superior. For flexibility and lower initial investment, portable dryers offer advantages. For a balance of efficiency, capacity, and grain quality, mixed flow dryers are often preferred.

By carefully considering the factors outlined in this analysis, corn farmers in the Upper Midwest can make informed decisions about which grain drying system provides the best value for their specific operations.

References

Iowa State University Extension, "Managing High-Moisture Corn"
University of Minnesota Extension, "Natural-Air Corn Drying"
Purdue University Extension, "Comparison of Alternative Grain Drying Systems"
USDA Agricultural Research Service, "Energy Efficiency in Grain Drying"
Sukup Manufacturing Co., Technical Specifications
GSI (Grain Systems Inc.), Product Documentation
Shivvers Manufacturing, System Specifications and Operation Manuals
Farm Progress, "Choosing the Right Grain Dryer"
Successful Farming, "Grain Dryer Buyer's Guide"
AgWeb, "Grain Drying and Storage Costs"
NewAgTalk Forums, User Discussions on Grain Dryer Performance
The Combine Forum, User Feedback on Various Dryer Types
Manufacturer Interviews and Product Demonstrations
On-farm Observations and Operator Interviews