Crop Systems have recently undertaken a major project for a large fresh produce supplier.

 

The project included updating existing cold storage facilities for over 1500 tonnes and design and installation of a ground-breaking 840 tonne warming store.

Warming Store:

The 840 tonne system has been designed from scratch using 14 individual warming pods.

Moving away from the current warming systems available, this innovative design uses low temperature air to warm the potatoes to approximately 10 degrees in 3 to 4 days. This has lead to a massive reduction in thumbnail cracks, whilst also maintaining the advantage of reducing the bruising that is prevalent in processing low temperature potatoes . The has also lead to another major advantage being the option to use low-grade heat from ambient air, whether used directly or from air source heating.

Specially designed control systems run the 14 pods automatically, each with its own variable speed fan, to match the incoming produce temperature. This enables the potatoes to be warmed from any given temperature to the target temperature regardless of loading patterns & differentiating crop conditions, but matching the time requirement for throughput. Even though there may be 14 different target temperatures, the crops within the pods can be loaded and/or unloaded seamlessly regardless of loading patterns and input temperatures.

Heating, cooling and an inline humidification system that continuously feeds the 14 pods have been designed using an air source heating system that has been utilising low grade heat from the ambient air since December 2008 (throughout the coldest periods since its commissioning!). A backup heat system drops in for the odd time it needs to defrost the air-handling coil and backs up the system when starting from empty.  The system again has variable speed drives to optimise the output to suit the ever variable requirements. The unit has an approximate COP (Co-efficient Of Performance) rating of 3.3 to 1 that gives very cost effective energy.

The system also takes waste heat from the adjoining cold store condenser unit when available. The heat unit being inverter driven to take advantage constant changes in the British weather.

In a reverse of the cooling process, the air system is optimised to take advantage of ambient air whenever available. Similarly, highly insulated air inlet doors in rubber sealed frames utilise the age-old industry method of air-mix with the advantage of modern leak-proof construction.

The system is extremely easy to use and very forklift driver friendly - insert a sensor, load the pods, wait 4 days, unload the pods, start the next cycle!

We have worked on a design that exploits energy transfer between the different requirements of the produce on an annual basis, saving energy whilst degrading stock is not an option.

The benefits of this system are far-reaching and are still becoming apparent with less wastage, less downtime, reduced reprocessing of substandard material, massive savings on energy and the ability to plan factory requirement schedules.

Following a recent visit to the site by Sutton Bridge Experimental Unit’s Adrian Cunnington, he had this to say:

‘The industry has not seen a warming chamber of this size and sophistication before. It has the potential to make a step-change in the reduction of damage and wastage incurred in the packing sector’.

Adrian Cunnington

National storage advisor

Potato Council