FabricAir A/S
Islandsvej 3
4681 Herfolge
Denmark
Phone (+45) 5665 2110
Fax (+45) 5665 9907
info@fabricair.com

FabricAir Ltd.
2 Sherwood Crescent
Rotherham, S60 2NJ
Phone (+44) 01709 835 989
Fax (+44) 01709 835987
to@fabricair.com


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07.06.2004

Air Distribution in Cold Stores

Optimal air distribution in cold stores will improve the product quality significantly, and will contribute to ensure low energy consumption. Unfortunately, far too many cold stores are made without any particular regard for the air distribution, thus producing poor results. Considerable funds are spent on investments producing a poor effect, and besides the end customer will frequently land up with poor operating economy.

By Brian Refsgaard

These problems are frequently due to traditional solution choices which do not allow for the individual problem complexes of the end customer. FabricAir A/S has taken its stand on this phenomenon. In lieu of this, solely customized solutions, always documented based on the particular problem complexes, will be applied.

Cold Store Build-Up

Cold stores are currently built up with pallet racks upon which the goods are replaced at varying intervals. New arrivals will frequently have a temperature higher than that of the other products in the room. This demands a great deal from the air distribution as quick equalizing of the temperature differences is required with a view to the quality of the product as well as to the operating economy of the cold store.

At Dragsbæk A/S, FabricAir A/S has supplied textile channels with nozzles used in the high-rise store of that company. This solution provides air distribution without heavy temperature gradients.

Dragsbæk A/S accurately monitors the temperature distribution in all the company production and storage sections. In the areas having textile systems, the temperature gradients are 0 – 0.5 °C. Compared to similar rooms without textile systems, these will frequently see gradients of more than 2° C. High gradients lead to variable product quality.

The air throw length is simulated using CFD. Despite the high velocity out of the nozzles, all systems are basically dimensioned with a view to establishing a draught-free common zone.

On account of the optimized air distribution, a cold store may normally be established with very low temperature gradients. The CFD simulation shows an example of the temperature distribution in a cold store with pallet racks.

Procedure

FabricAir A/S has, in a manner highly successful, supplied several air supply solutions for cold stores based on textile channels with nozzles. Textile channels have been used for many years in cold workrooms – particularly because the air is supplied free of draught, noise, and condensation. When the textile channel is made with nozzles, entirely different injection principles will be applied but the solution will remain entirely free of condensation and will, made correctly, yield no noise.

Uniform temperature distribution requires good mixing of the air. If temperature gradients are to be avoided, the focus must be on the air distribution. In rooms having high ceiling height, the risk of a temperature difference between floor and ceiling is obviously very considerable so a good knowledge is required of the movements of the air in the room to identify the optimal solution. Further, air inlet equipment with extremely high flexibility for exhaust will be required. A textile channel with nozzles meets these criteria.

The throw length on the air supplied will depend on many parameters; the following will, for instance, bear heavily on this: Pstat in the textile channel, temperature difference, room temperature, thermal air flows in the room, etc. An exact view of the result expected will be impossible without specific computation.

Through CFD simulations, IPS ventilation A/S will attack each particular cold store individually, and not until the optimal positioning of nozzles has been found, and the correct throw lengths calculated, will the channels be produced.

References

One example of a well functioning cold store is that of Dragsbæk in Thisted (see photo). This cold store has pallet racks with products, and here the air distribution is certainly most important. This cold store has been supplied by York Køleteknik A/S who chose IPS Ventilation for the making of an air distribution system.

Similar solutions have been supplied for stores particularly at Novo Nordisk and Arla.

Facts on FabricAir A/S

Over the last 30 years, FabricAir A/S has been specializing in air distribution of sub-cooled air. This know-how is to-day supported by CFD calculations for documentation of the optimized distribution. In addition to the supply of textile systems, FabricAir A/S also runs a complete service & maintenance program offered to all customers in Denmark. Our company employs a staff of about 75, with sales offices in Denmark, England, and the USA. Our company runs production in Denmark and in Lithuania.

The nozzles may be placed entirely as required on the textile channels. Thus allowing for full optimizing of the air distribution based on the CFD calculation implemented.