BROCHURE

Process Freezing
Eliminate ice and frost, increase throughput,and exceed quality requirements

Humidity control is essential
in process freezing
High volume, fast-paced production systems in continuous operation make up themajority of process freezing operations. Uncontrolled humidity in food production
facilities can cause expensive and unproductive interruption because of the need todefrost evaporators and remove ice from conveyors, floors and walls.
Desiccant dehumidification removes moisture from the air before it can form frost
and ice on equipment. With ice build-up and defrost cycles significantly reduced,
process freezing operations can run smoothly and at high speeds year round,regardless of season.

2Desiccant dehumidification
for blast and spiral freezers
A blast or spiral freezer is a criticalcomponent in most frozen food production
processes. One of the largest challenges
to maintaining performance of blast or
spiral freezers is frost build up in the freezer
and on evaporator coils. A Muntersdesiccant dehumidification system canprovide dry air to blast and spiral freezers
with the following benefits:

Munters ICA• Significantly reduce or eliminate frost on freezer cooling coils to minimize or
eliminate defrost cycles, resulting in improved freezer cooling performance.
Evaporator coils with minimal frost have higher cooling capacity. This allows moreconsistent and higher product flows through the freezer because the cooling coils
can cool more effectively and efficiently.
• Significantly reduce or eliminate frost at the freezer inlets, outlets, and conveyors.
This insures higher food quality by eliminating product damage caused by contact
with frost or damage by conveyor malfunction due to frost build up.
• Eliminate the need for employees to remove frost manually or by complete
freezer shutdown and defrosting with a heat source. This can significantly
improve productivity and reduce the chances for workers to be injured due toslipping or falling.

3

Moisture infiltration anddew point control
The principal design concerns for food freezers are quantifying the moisture infiltrationand determining the appropriate control dew point.
If the installation is already in place, the designers job is as simple as taking surface
temperature readings on the walls, floor, and conveyor supports where ice formationmust be at a minimum. The control dew point will be slightly below that surfacetemperature.
In some cases, the temperature is so low that it would be economically impracticalto maintain the dew point low enough to prevent all ice formation. It may be necessary
to determine what temperature is economically feasible and assume there will be some
ice formation, but at a much reduced rate.
The lower the dew point, the more efficient the refrigeration system becomes. The
result is less frost on ceilings and conveyors. By removing the moisture at its source –before entering the cold space – the system will operate more efficiently.
Determine the loads
Moisture loads come from air infiltrating through doors and conveyor openings, as wellas, evaporation from the product.
Infiltration air – Factory or outside air entering the space carries the largest moistureload. Air enters as a door is opened, or continuously through openings aroundconveyors. In both cases, it is important to reduce this load to a minimum through theuse of entry tunnels and vestibules. Additionally, door openings inside on the freezer
should be limited to minimum.
Product moisture – Water vapor from the product is relatively easy to quantify by simply
weighing the product entering and exiting the freezer. The difference in weight is largely
moisture. If the product is wrapped before freezing, this load will be close to zero.
4The Munters Solution
Munters dehumidifiers have a desiccant wheel that rotates slowly between two
primary airstreams, process and reactivation. In the process airstream water vapor
is removed as it passes through the desiccant wheel. This dehumidified air is thendelivered to a manufacturing process or space. The wheel then rotates into thereactivation sector where a heated airstream is passed through the wheel. The
desiccant wheel releases the water vapor to this airstream.
In contrast to cooling, the desiccant process becomes more efficient as thetemperature of the air decreases. Munters units have no difficulty producing air
dew points of -30° F and lower. This allows you to create dry, wintertime moisture
conditions during the summer.
Since the Munters unit removes moisture from the air to levels below theevaporator’s temperature, it no longer freezes on cold surfaces in the room, whichmeans refrigeration equipment operates more efficiently, with fewer evaporator
defrost cycles, fewer conveyor jams due to ice build-up and safer, less slippery floors.
Munters has spent decades improving and optimizing the desiccant dehumidification
process including patenting technologies like PowerPurge® which significantly reduces
reactivation energy requirements and post cooling requirements.
Munters HoneyCombe® Rotor Technology with PowerPurge™

5

Wet Air
OutletWet AirOutlet

Honeycombe®
Dehumidifier

Reactivation
Inlet Air

Reactivation
Inlet AirDry Air
SupplyAir fromPlant or OA

Tunnels Added atFreezer Openings

Process Freezer

Figure 1. Makeup
AirTunnels with Tunnels
Fig.
1 System
Makeupwith
Air System

Dry Air
SupplyCoils

Return Air

Coils

Conveyor

Honeycombe®
Dehumidifier

Conveyor
Openings
or Doors

Return Air

Process Freezer

Conveyor
Openings
or Doors

Figure 2. Air System
Fig. with
2 Air Vestibule
System with Vestibule

Types of process freezers
No Vestibule (Figure 1) – Frequently a spiral freezer or blast freezer is built without avestibule. While vestibules are often impossible to install for space reasons, conveyor
tunnels are essential to minimizing icing inside the freezer. Figure 1 explains thesystem graphically. Air is taken from the ambient plant (or outside air if the plant has anegative pressure), processed through the dehumidifier and supplied to the conveyor
tunnels. The air should be enough to maintain a minimum of 100 FPM air velocity forthe conveyor openings.
Vestibule System (Figure 2) – When space allows, the vestibule system may be allthat is required to minimize moisture in the process freezer. It has the advantages of low
cost and simplicity in installation. Figure 2 explains the system graphically. Air is takenfrom the vestibule, processed through the dehumidifier and returned to the vestibule
area just in front of the freezer conveyor entrance. This ensures that any air that
infiltrates into the freezer is dry air with a moisture level below the temperature of theevaporators. The dehumidifier can be switched on by a condensation controller, set tomaintain the air at a specific dew point.

6Conventional systems
cannot efficiently removemoisture
Process freezing systems are designed to remove sensible heat from a product rapidly
and efficiently. However, they are not designed to efficiently remove latent heat –moisture – from the air inside the freezing chamber.
While cooling coils can be automatically defrosted, ice on conveyors and floors
must be removed manually, causing production to slow down or stop. Additionally,
the defrosting of coils adds a heat load to the freezer and takes the coil off line, which
can impact the freezers ability to keep cold temperatures. Also, the cooling capacityof the evaporator coil is reduced significantly as the coil builds up frost, so the amountof product cooling is reduced. This means that product cooling rates can vary with coil
frost, yielding uneven production quality and throughput.
For some freezers, the need for a defrost cycle causes production to stop or slow
down due to loss in capacity, resulting in expensive and unnecessary delays.
To reduce icing, the moisture in the air must be reduced. Refrigeration systems lack thecooling capacity to produce low air dew points when humidity is high. The coils freeze
with condensed moisture before a low dew point can be achieved. Also, when you use
an evaporator coil to remove moisture, it discharges air at saturation which means that it
does not have the ability to absorb any additional product or infiltration moisture.

7Munters Service With you all the way
With Munters as your service partner, your air treatment equipment will receive theattention, care and maintenance needed to reach its maximum life expectancy.
Throughout each phase of the equipment life cycle, the knowledge and expertiseof Munters Service will insure optimal operation, minimum energy consumption, andextension of the life of your investment.
Our range of services available through our global network of Munters ServiceEngineers and Technicians include:• Comprehensive installation and start-up services• PrimaCaire™ (extended warranty) agreement• Flexible ServiceCaire™ maintenance agreements to fit your specific needs• Performance checks and optimization

BR-PROCESS FREEZING -202104-EN• Numerous upgrade options for substantial energy savings and improvedperformance

Find your nearest Munters office at www.munters.com
Munters reserves the right to make alterations to specifications, quantities, etc., for production orother reasons, subsequent to publication. © Munters AB, 2021