Bulk Storage Systems

For potatoes, onions and root vegetables

Storing in bulk is suitable mostly for potatoes, onions and some root vegetables. The main advantage of a bulk storage system is the fact that air passes around each tuber and therefore can better influence the storage process (compared with pallet storages). However, this system places significantly higher demands on the precision of ventilation and refrigeration technology, because the impact on the produce is immediate. Demands for air supply are also higher than in the case of pallet storages. Required air supply ranges between 100 - 300 m3/t/hour at 150 - 300 Pa air pressure depending on the type of produce. The advantage of storing in bulk, however, lies in a better possibility of influencing the quality of produce.

Bulk storage

Mixing chambers of bulk storage areas are usualy built as a part of storage construction. Aeration ducts can be placed above or below a storage floor. Agroel supplies wooden triangular or metal semi-circular aeration ducts. Underground aeration ducts can be covered with wooden or metal grids. The correct design, dimensions and shape of aeration ducts and mixing chambers are the subject of a qualified calculation. Let an Agroel professional do it for you!

Comparsion of box-storage advantages and disadvantages

Even aeration in the pile because of pressure-air ventilation
Efficient post-harvest surface drying of the produce
Better possibility of maintaining even temperatures in the whole storage area

Limited possibilities of storing different varieties in a single storage unit
Not as flexible as pallet storages for loading and unloading
Building adaptations for a bulk storage are usually more demanding (in comparison with pallet storages)
Higher energy costs in comparison with pallet storages

See how Agroel bulk storages work

Components of bulk storage

Agroel supplies complete solutions for box storage. Below you can find information on their main components:

1. A fan distributes air throughout the storage.
2. An inlet control hatch lets the fresh outdoor (ambient) air enter the storage area. The ambient air can be mixed by the hatch with indoor air in order to achieve the required temperature of the air that enters the storage area(compare to a bathroom water valve). The hatch is operated by an electric linear or radial actuator with a position sensor.
3. An outlet hatch lets the warm air leave the storage area. The hatch is usually placed near the storage ceiling in one of the outside walls, often in the same wall as the inlet hatch. It is also operated either by a radial or a linear actuator.
4. An evaporator (cooler cools recirculated indoor air that passes through it. An evaporator consists of copper pipes for refrigerant distribution and lamellas for heat transfer.
5. Air-humidifying panels not only humidify the air that passes through them, but can also provide a significant cooling effect.
6. Hatch toothed drive racks can be used for operating multiple inlet and outlet hatches. Racks are not needed if linear electric actuators are installed, because usually one linear motor controls one hatch.
7. Radial or linear electric actuators are used for operating hatches.
8. Retaining walls. The walls of some storage facilities are not constructed to withstand the high pressure of a produce pile. For that purpose, Agroel supplies removable retaining walls. These removable retaining walls can also be used to partition a large storage unit into smaller cells.
9. Pressure chamber (plenum) is a very important part of a ventilation system. It distributes air pressure into lateral ducts. The pressure chamber, mixing chamber and lateral ducts are subject to qualified calculation and design.
10. Ventilation ducts can be placed above or below the floor. For storage adaptations, where the concrete floor is usually finished, the above-floor ducts are usually more favourable. In other cases, we recommend underground ducts.

Examples of some bulk storage designs

Mixing chamber

Mixing chamber - inlet and outlet hatches and fans


Outlet hatches and their operation by a radial electric actuator and racks

Pressure chamber

Pressure chamber with humidifying panels

Mixing chamber

Mixing chamber - inlet hatches and fans

Storage solutions and a project preparation

A professional design of a ventilation system is fundamental for your future storing success. Agroel specialists will be glad to offer their advice to solve any of your storage problems and help you meet your needs. We provide consulting services free of charge to all our customers.It is not a simple task to correctly design and calculate aspects of storage facilities. We have already created hundreds of alternatives for customers with bulk storage facilities - let us create alternatives for you as well.

Design and calculations. The following details outline what calculations and designs are necessary to successfully create an appropriate storage facility to suit our customers' needs.

● Calculating the required air volumes for all storage phases and choosing the right fans
● Calculating the inlet and outlet hatch areas
● Calculating and designing the mixing chamber
● Calculating and designing the pressure chamber
● Selecting and designing ventilation ducts. This process includes the calculation of gaps in the ducts for even air distribution along the whole length of a storage area.
● Correct programming and setting of the Agroel control system with regards to the storage type and requirements for the particular product that is going to be stored