Process Freezer Humidity Control Case Study: Reducing Ice and Condensation
See how controlled dehumidification reduced unstable humidity from 60-80% RH to approximately 20% RH around a process freezer at a Queensland food processing facility, helping control condensation, fog and ice.
PROJECT AT A GLANCE
Client: Large meat processing facility
Application: Process freezer and antechamber humidity control
Location: Queensland, Australia
Challenge: Humidity fluctuating between approximately 60-80% RH, contributing to condensation, fog and ice
Target humidity: Approximately 20% RH
Solution: Dehumidification combined with improved management of door openings and strip curtains
Monitoring: Data logger testing before and during controlled operation
Outcome: Humidity stabilised at approximately 20% RH, with substantially reduced fog and ice build-up
THE CHALLENGE
A large Queensland meat processing facility was experiencing unstable humidity within the controlled area adjoining a process freezer, with recorded relative humidity regularly fluctuating between approximately 60% and 80%
The site already had automatic doors, strip curtains and dehumidification equipment in place. However, extended door-opening periods and strip curtains being held open allowed warm, moisture laden air to enter the controlled area.
As humidity increased, condensation, fog and ice began to return - creating less stable operating conditions and increasing the moisture load on the refrigeration system.
BASELINE HUMIDITY CONDITIONS
Data loggers were used to measure temperature and relative humidity within the antechamber adjoining the process freezer.
Blue line: humidity. Yellow line: temperature
Data logging over a three day period showed significant variation in relative humidity. At times, RH increased towards 60–80%, well above the approximately 20% RH required for stable operation.
This process freezer has automatic doors, strip curtains and a dehumidifier installed. However… door opening times were sometimes longer than necessary and strip curtains were pulled up and left up.
As you can see the humidity is all over the place (blue line). And condensation, fog and ice began to creep back into the storage area.
HUMIDITY CONTROL WITH DEHUMIDIFICATION
Below Graph - Same process freezer – data over a four-day period.
Blue line: humidity. Yellow line: temperature
During the monitoring period, the dehumidifier was switched off and then recommissioned, allowing the effect on room humidity to be clearly observed.
Once dehumidification was restored - together with better control of door-opening times and strip curtains - relative humidity stabilised at approximately 20%.
The comparison demonstrates the importance of both effective dehumidification and good operational practices. Dehumidification removes the moisture entering the space, while limiting door open time reduces the moisture load entering in the first place.
THE OUTCOME
With the dehumidifier operating correctly and staff reducing unnecessary door-open times, relative humidity became considerably more stable at approximately 20% RH.
The lower and more consistent moisture level substantially reduced the conditions responsible for fog, condensation and ice formation around the process freezer.
RESULT AT A GLANCE
~20% RH maintained
compared with 60–80% RH fluctuations previously
Why Does Ice Build Up IN COLD STORAGE?
Ice forms when warm, moisture-laden air enters a cold store or freezer and contacts cold surfaces. Water vapour condenses and then freezes on floors, walls, doors and evaporator coils.
Door openings are one of the most common sources of moisture ingress. The longer a door remains open, the greater the amount of humid ambient air entering the controlled space.
Three Ways to Reduce Ice in Cold Storage and Process Freezers:
1. Minimise door-open time
Every time a cold-store or freezer door opens, warmer moisture-laden air can enter the space. Reducing how long doors remain open helps minimise the moisture load on the refrigeration and dehumidification systems. Rapid doors, timers and good operating practices can all help.
2. Use strip curtains or rapid doors
Strip curtains provide an additional barrier between the controlled environment and ambient air while allowing staff and equipment to move through the opening. They won't eliminate moisture ingress entirely, but they can significantly reduce the amount of warm, humid air entering the space.
3. Control incoming moisture with dehumidification
A correctly designed dehumidification system removes moisture from the air before it can contribute to fog, condensation and ice formation. In cold-storage applications, dry, low-dew-point air can be supplied around entry points to help maintain more stable humidity conditions despite regular door openings.
Experiencing condensation, fog or ice in a cold store or process freezer? Humiscope can assess the moisture load and design a dehumidification solution to maintain more stable conditions.