FEATURE
INCORPORATING COLD CHAIN
Matador Refrigeration
As a result , there has been a dramatic shift in the approach to refrigeration , but more so improved designs that professionals in this space are responsible for , and the facility design and operations as a whole will have to continue to evolve ”, notes Permacold Engineering .
Natural refrigerants as the major drive in engineering design changes have increasingly proven their value and safety over the last decade . The move to higherefficiency , leaner systems that rely on natural refrigerants like CO₂ and ammonia , are essentially already the norm on a global scale , particularly as more international investment is seen in South Africa , and as we compete on the international level , such clients are become increasingly aware and more demanding in better sustainability throughout the supply chain .
“ As the shift towards natural refrigerants progresses , looking back , CO₂ technology has shown rapid adoption locally . What was first introduced into South Africa started out with equipment for retail clients where subcritical CO₂ designs were used . We then started to move to first world transcritical technology and systems based on Beijer Ref Italian company , SCM Frigo designs . Our first transcritical unit was supplied into South Africa in 2018 . From then onwards the technology and range of CO₂ equipment has just grown . The range in CO₂ equipment today includes everything from small applications right through to multi-megawatt facility applications . We can offer a full solution on CO₂ units while this as a refrigerant allows a green solution for our clients and to meet the demands , we are moving in that direction . We all know that we need to be moving to natural refrigerants , and the reasons behind this . CO₂ is obviously not the only green or natural solution out there . On smaller applications in future , we will definitely see R290 coming up the ranks into the selection pool as well . From the commercial side we believe CO₂ will be prominent while on the higher end of the industrial scale , above three megawatts , ammonia will remain the most competitive solution for now . We will continue to support all of our clients in whichever natural solution they choose ,” says Metraclark , part of the Beijer Ref Group .
Permacold Engineering adds , “ In the future , the refrigeration systems operated and maintained in many facilities will no doubt have to meet certain criteria and may be characterised by having a smaller footprint , be limited in their power
A typical transcritical CO₂ plant . consumption , and rely on the latest technologies developed , catering to natural refrigerants only . The increasing demand for high efficiency , low maintenance systems will also inevitably force a change in the typical approach to systems designs as clients themselves will seek out far lower energy bills , the reduction in use and costs of resources such as water , sewage and chemicals , and improved sustainability of system and component materials .”
The South African sector has seen the largest growth in CO₂ systems over the last two years as well as the availability and supply of CO₂ system components from international suppliers .
“ Using CO₂ as a refrigerant is definitely not anything new though . This refrigerant has in fact been used for over 15 years already , and in different forms . At the beginning stages of its use , CO₂ was primarily used for low temperature applications ( freezer applications ). In the medium temperature applications ( chillers ), and the high temperature ( drop-down areas ). CO₂ wasn ' t used as a refrigerant because it operates at high pressures and the technology at that stage did not exist to use it . Typically , at that time , designs made use of a cascade method , while today the use of CO₂ has been very well refined and can be used for all applications . Transcritical CO₂ plants are common as they enable the handling of low to medium temperatures and high temperatures through the inclusion of intermediate or parallel compressors . This method has now been in use for about six years and locally various larger supermarket groups have been shifting over to transcritical CO₂ over recent years ”, according to Matador Refrigeration .
Although adoption of natural refrigerant plants has seen a lot of activity for bigger players , initial capital costs are higher , and so at this point in time not all companies have the necessary funds to make a shift and must rely on maintaining their existing plants .
“ We have to all understand that natural refrigerants are the future and are going to take over the market at some point whether companies like it or not . This is a particular drive for internationally recognised chains who are on the fast track to go green but further than that these new systems are far more energy efficient and provide significant savings in operational costs quite quickly . CO₂ plants ( especially transcritical ) also work differently because there is for example no condensing ( when the refrigerant reaches transcritical state ), and state change occurs through gas coolers . Liquid tanks are also different to traditional Freon systems , as well as the compressors and piping . Due to the high pressures involved copper cannot contain the pressures reached during transcritical state so stainless-steel tubing need to be used ,” notes Matador Refrigeration .
AHT
Many plug ‘ n play cabinets and island fridges / freezers already make use or R290 ( propane ) refrigerant in retail applications .
Not all geographic areas however can accommodate CO₂ systems currently . In Northern Africa , for example , the technology is not there yet in terms of using transcritical in high ambient conditions . In time it is expected that this challenge will be resolved and a successful solution in all ambient conditions will be developed . The main concern in this ( under current technology circumstances ) is the standing pressure ( the plant not being in-use for whatever reason ). Plant equipment or any vessel currently on the market is just not able to withstand the overall pressure as this may exceed 110 Bar . Equipment may well be able to be manufactured of course , but the costs would be excessive .
“ We have chosen to offer CO₂ solutions to our clients because in various trials we have discovered that this refrigerant could produce equal results in large scale industrial plants where ammonia has been a better solution in the past . Also , when considering the other natural refrigerant – R290 , volumes required in commercial and industrial applications cannot be met , or don ’ t make sense ,” Matador refrigeration adds .
THE LATEST IN EQUIPMENT AND COMPONENTS Each category in the refrigeration sector is continually developing to enhance efficiency through not only improved design but new techniques , materials , and electronic controls .
“ As the sector evolved a lot with Freon plants over the year , so too will the next stage be in terms of natural refrigerants . Each small component in a system makes a difference in the overall goal of energy savings . What we have been trying with our CO₂ plants is de-superheating in the system which is quite new method and cools the gas in a quicker way . Other equipment performance worth mentioning is the improvements in variable frequency drives and fan motor technology ,” says Matador Refrigeration .
Facility insulation , door and loading area seals , internal facility heat loads , and general monitoring and control methodology are all additional factors that continue to gain improvement in facility lifespan and plant performance .
“ Variable speed drives , which are really a complex system of control hardware , power supply and software , are designed to adjust the power supplied to a motor from the main power input to modulate operating speed . They can manage the performance of compressors , pumps , or fans . This means that these components can operate at variable capacity , bringing significant energy savings to refrigeration systems . Compressors are the most energy consuming components of refrigeration circuits , thus the use of inverters to increase their performance is being rapidly extended .
In practice , inverters provide the best way to avoid inefficient on / off cycles that reduce the compressor ’ s seasonal efficiency . This means that , at part load or in low load conditions , an inverter-driven compressor adapts cooling capacity to system requirements without stopping it completely . Currently , the most efficient technology for inverter-driven compressors is called BLDC ( BrushLess Direct Current ) or simply DC . Permanent magnet brushless motors differ from more traditional asynchronous motor technology in that the compressor rotor consists of a permanent magnet instead of an electric coil . This allows higher motor efficiency ( no energy is consumed to magnetise the rotor , as in the case of asynchronous motors ) and a wider range of speeds , from 600 to 8000 rpm , while asynchronous motors are limited to 1500-6000 rpm . These features of DC compressors , together with the use of inverters , highlight their efficiency at part loads , giving higher seasonal efficiency and performance in terms of cooling or heating capacity control , with precise load management and constant control of the compressor envelope . It should be noted that inverter technology cannot be used without adopting electronic control systems that instantly calculate the optimum compressor speed , and electronic expansion valves , the only expansion technology that can adapt to the variations generated by the compressor ,” notes Carel Industries .
As the planet heats up too , according to International Energy Agency ( IEA ), it ’ s estimated that globally 3.5 times more cooling will be required by 2050 than today . At present , refrigeration and air conditioning systems already consume around 15 % of global electricity production .
“ In addition to the transition to natural refrigerants , another hot topic these days is the use of heat pumps in refrigeration applications . GEA recognised the application potential and benefits of heat pumps
20 www . coldlinkafrica . co . za COLD LINK AFRICA • October 2021