PROJECT
INCORPORATING COLD CHAIN
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Precool Cold Storage perishable products , according to the required temperatures for such export . This accreditation ensures fulfilment for required protocols .
PROJECT CHALLENGES
One of the main challenges during this project was the earthworks that needed to be done and pushing through the rainy season ( and flooding ). Because of the gradient on the property this required extensive civil work that included piling and erecting various immense and complex earth retaining systems across the property which also contributed significantly to the costs on the project .
In terms of the refrigeration , the ability to change the rooms from low temperature to medium temperature and vice versa , as specified by the client , was
a noteworthy challenge for Commercial Refrigeration Services ( CRS ) who designed and installed the refrigeration .
This required valve changeover stations at the packs and common suction lines to each blower coil . The packs were then designed to handle the maximum low temperature or maximum medium temperature requirement .
According to CRS engineers , generally if you think about any cold storage facility , it will have a dedicated freezer room and cold room ( so it operates as either of these ). Precool Cold Storage wanted the functionality of multitemperature choice in order to maximise the utilisation of the cold store throughout the year . Essentially being able to operate as a medium temperature cold store or freezer facility while waiting for the next season ’ s produce to be ready for export .
The coils had to thus be designed to handle both option ’ s operation . The difficulty came in here for CRS , but managed to come up with a design
1 . The gas coolers installed outside the main refrigeration plant room .
2 . The facility has seven docks - ready to handle deliveries and collections .
3 . The steri-rooms have a 2 500 pallet capacity .
4 . Guard beams are installed at every entrance to protect against any forklift bumps or damage .
5 . An open picking isle in one of the room ’ s mobile racking system .
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solution for the low temperature . Not all the coils would then operate when low temperature options are implemented . This particular design was something CRS had not done before , so the piping is quite different because with this CO 2 system there is not only a common liquid line that goes to all of the evaporators , but also a common suction line that had to be designed to ensure proper operation under medium temperature or freezer applications – so this method changed the design and the installation in the plant room with changeover valves , and so on .
ENERGY EFFICIENCY
The system ’ s impact on energy efficiency and sustainability includes an energy efficient CO 2 system with adiabatic gas
coolers , parallel compression , hot gas defrost and heat reclaim . Variable speed drives ( VSD ) on driven compressors , electronic controls and permanent magnet compressors also provide exceptional efficiency . The use of CO 2 is relevant to address the environmental aspects in terms of global warming potential .
The hot gas from the system that comes from the discharge of the medium temperature compressors is circulated through the system and this defrosts the coils instead of using electrical defrost elements , which creates a substantial saving . This energy saving technique works very well and has been vastly implemented worldwide – basically using free heat through the discharge . The coils do have electrical elements as a backup , as this was specified by the client , but they won ’ t operate unless manually switched on if required .
VSDs have been around for a long time and play a key role in driving efficiency . On each temperature group they allow the user to start up the pack slowly ( soft start ) reducing the initial energy use at the start and also allows the system to operate at different capacities – essentially meaning one does not have to operate the plant at 100 % capacity all the time , wasting energy – if you need to run down to 10kW , this can be done , where all of the compressors will be off , except the one with the variable speed drive in operation .
24 www . coldlinkafrica . co . za COLD LINK AFRICA • March / April 2021