Ed Whinyates of Stonegrove Refrigeration and Simon Mills of dehum examine the issues that moisture can cause in cold storage facilities and the most efficient and cost effective solutions to resolve this.
High humidity can often play havoc within many manufacturing processes. Unfortunately, it is hard to detect and often overlooked as the reason why production is being affected or even halted.
Creating the correct environment can improve production efficiency, reduce downtime, eliminate bottlenecks, ensure consistent production rates and improve Health & Safety standards.
Chilled food distribution centres and commercial cold stores present their own unique issues to deal with. Anywhere that reduced temperatures are required to protect or store chilled or frozen products, has the potential for serious issues in relation to:
- Ice and snow inside the cold store
- Risk of falling ice
- Frost shock on product
- Failure of door mechanisms
- Increased running costs of refrigeration plant
- Increased defrost cycles
- Health & Safety
Why does moisture develop?
We have all seen snow and ice on product, ceilings and internal evaporators within cold storage facilities. This is created when store openings allow moist warmer air in adjacent areas (marshalling or ambient stores, for example).
Each time a door is opened to a cool or cold area, air and moisture enter from any adjoining untreated source. This air is then rapidly cooled and the moisture contained within it is deposited on the coldest surfaces. Depending on the temperature in the room, this moisture will then appear as condensation or frost.
This can build up and create Health & Safety issues for personnel and for the transportation of goods.
How can moisture be prevented?
The use of a desiccant dehumidifier⁴ in these instances deals with the moisture at source and the units themselves create a low dew point in the air in any neighbouring areas. By removing the moisture at source, the dew point can be reduced dramatically to a point where there is simply not enough moisture to condense on the cold surfaces. This means that when the doors into the cold areas are opened, there is insufficient moisture to create condensation or snow/ice within the facility.
Simple dew point control can be incorporated into the control software in the units to ensure that only the minimum amount of energy is consumed to create the condition needed to overcome the risk.
Removal of moisture in this way also has the added benefit (for the cooling plant) of removing the latent elements of the load from the air, allowing evaporators to run drier, with fewer defrosts and improved plant efficiency.
What should you do next?
Speak to a specialist in this field and arrange a site visit, so your facility can be assessed. dehum has a range of dedicated cold store machines which have been developed to deal with the rigours of installations in these types of hostile environments and effectively manage the humidity within cold storage.
¹ Psychrometrics – the science behind the behaviour of air. Used to calculate how the various conditions that interact with air can be modified, to produce the ideal conditions required by a multitude of production processes.
² Relative humidity (RH%) – measured as a percentage of the amount of water vapour in the air relative to the amount of water the air can hold at saturation.
³Dew point (dpt) – measured in 0C dpt, it is the temperature of the air at saturation. The point at which the air can no longer hold the moisture; 100%RH is reached and water starts to condense.
⁴ Desiccant dehumidifier – a specific type of dehumidifier used to extract moisture from the air. A desiccant dehumidifier uses a slowly rotating wheel which holds the desiccant material. It is particularly effective, even when used in extreme temperatures.