Talk to anyone you choose in the grain industry. Ask them for advice about selecting a new grain dryer, and one thing is certain. You can bet they will tell you to at least consider a mixed-flow grain dryer before making your final choice.

The concept behind mixed-flow grain dryers isn’t new. Mixed-flow dryers have been on the market for decades, and many have performed admirably at elevators and commercial grain operations. However, they have not typically been found in on-farm grain systems. Why are they making their way to farms now?

“Higher grain quality is a big advantage for mixed-flow dryers over most conventional dryers,” explains Jeff Cravens, GSI regional director for sales in the eastern Corn Belt and Canada. “They operate at lower cfm [cubic feet per minute] per bushel than other conventional, portable dryers, and that delivers better grain quality.

“It’s similar to airflow with a GSI TopDry system, which is technically an in-bin dryer. TopDry systems also produce good grain quality and are very efficient.

“Fuel efficiency is the other big advantage for mixed-flow dryers over most other portable, conventional dryers. They are very economically friendly to operate.”

GSI is putting finishing touches on a mixed-flow dryer and plans to launch it for the 2025 season.

No screens

Jeff Cruzen, dryer business development representative for AGI, says another beneficial feature of mixed-flow dryers is that they don’t have screens like conventional dryers. There are no screens that can plug up with beeswings and other debris, and no screens to worry about cleaning and maintaining.

That’s where mixed-flow dryers pick up part of their efficiency and extra capacity, he explains. Screens take up room and reduce space available for corn kernels, especially as they collect material over time during dryer operation.

Why else are mixed-flow dryers more efficient? Industry experts who have worked with the concept for a long time say the higher efficiency centers around lower airflow requirements, as noted earlier.

Conventional dryers with screens may require 80 cfm or more per bushel, while mixed-flow dryers often require 45 to 55 cfm per bushel, depending upon the model.

Grain stays in the dryer longer but at lower temperatures. The result is up to 30% lower energy costs and fewer stress cracks compared to grain dried in conventional dryers, based on numerous industry reports.

Reasons for the trend

So, is it all pluses for mixed-flow dryers? Why haven’t they appeared on farms earlier? Visit with reps from different companies at any major show, like the National Farm Machinery Show, Farm Progress Show or Husker Harvest Days, and you will discover that when the concept first took hold over 40 years ago, it was typically used in dryers at elevators and commercial grain operations. Most mixed-flow dryers were large machines.

Two trends are intersecting: On-farm grain handling operations are increasing in size, and companies are designing and installing different sizes of mixed-flow dryers, including ones suitable for small to medium-sized farm operations.

Brock introduced a new mixed-flow dryer recently called the Vector Energy Miser. Most companies now offer a mixed-flow dryer in their lineup.

One drawback with mixed-flow dryers is that more beeswings and similar materials wind up in the air, Cruzen says. For commercial elevators, which typically don’t have houses nearby, this may be less of a problem. However, it can be a consideration for an on-farm dryer, especially if the farmhouse is nearby.

“We’re offering a precleaner for our AGI mixed-flow dryer,” he notes. “It’s a brand-new feature, and it pulls off beeswings and other debris instead of letting them go into the atmosphere.”

INSIDE LOOK: This cutaway display from AGI shows the inside of a section of a mixed-flow dryer. Grain starts at the top and works its way down around the baffles. No screens are used in the drying process, simplifying maintenance with these dryers. 

How a mixed-flow dryer works

Not all mixed-flow grain dryers are alike. Some have unique designs, especially when it comes to how grain flows out of the dryer. But the basic concept is the same.

By definition, a mixed-flow dryer mixes air currents instead of air moving in only one direction. Cruzen uses a display model of the cross-section of a mixed-flow dryer to explain the concept. Look at the picture above.

“We’re changing airflow and flow of the grain,” he explains. “As grain moves down from the top, it is diverted by baffles, which have heat and air underneath. It continues moving down through a series of these baffles.”

As corn moves through the column, each kernel dries at an even heat. That’s one of the advantages of mixed-flow drying — less airflow and lower overall heat typically results in higher-quality grain.

Once corn reaches the bottom of the AGI dryer, two metering rolls regulate flow out of the dryer. There are various options in terms of augers for moving grain away from the dryer.