REFRIGERANTS Booster CO2 with emerson stream and scroll


refrigeration — are becoming a thing of the past. There is no one-size-fits-all solution within the next generation of refrigeration technologies. In addition to selecting alternative refrigerants, end users must make refrigeration decisions based upon a much broader set of criteria, including: leak identification and mitigation; energy-efficiency goals; sustainability initiatives; maintenance, servicing and operational requirements; and system costs (both first and lifecycle costs). New store layouts and available architectures are also something that end users must factor into their decision making. Keeping all these factors in mind, here are some of the leading refrigeration architectures that use low-GWP refrigerants.  CO2


transcritical booster — In hypermarkets,


supermarkets and convenience stores, CO2 transcritical booster technology has established itself as a viable natural solution for LT and MT cooling for the foreseeable future. Currently in Europe, more than 20,000 systems are already operating in food retail operations. To ensure a successful CO2


deployment,


operators should have access to a trained, skilled workforce for service and maintenance, and utilise a robust design to avoid shutdowns and charge losses. In moderate climates, CO2


Floor layouts are easy to change, and new stores (or refits) can be deployed and opened faster. Throughout Europe an estimated 9,000 stores are operating on integral display cases with a water loop, of which over 3,000 are using R290. There are known challenges with R290 as well. Because of its flammability, industry best practices recommend using the smallest charge possible. In addition, more compressors are typically needed than would be in a centralised system.


 Large condensing units — Another relatively new trend in Europe (particularly in France) is the use of multiple large condensing units in a ‘decentralised’ architecture. Instead of a centralised rack with single LT and MT circuits, several condensing units (up to two to three for LT and three to four for MT) are used to provide the total cooling requirement. Retailers have come to appreciate the benefits of a multi- system approach, which include the speed and simplicity of installation, less risk to total food loss due to multiple circuits, and the lower susceptibility of leakage with factory-made units. Compared to centralised systems, the ability to optimise each system’s evaporating temperature setpoint can also provide significant energy savings.


However, this approach is not always easily scalable to larger formats, where too many units would be needed to meet the total cooling load. As of today, there are limited options available


that utilise very low-GWP refrigerants; both CO2 and A2L units for LT are not yet broadly available for the required capacities.


systems


typically deliver high energy efficiency levels, but in warmer climates (South Europe), efficiency can be more challenging to achieve. Technology enhancements, such as parallel compression and the use of ejectors have helped to bring energy efficiencies in CO2


system to acceptable levels,


although at some additional cost. A persistent challenge with CO2


technology,


however, is economic scalability. The smaller the system, the higher the CO2


premium relative to


traditional refrigerant technology. Operators of smaller store formats are therefore more likely to explore other alternative refrigerant options.


 Integral R290 display cases — These flexible and efficient natural refrigerant options offer very low charges (more than 90% less than a centralised system) and are based on factory- built, hermetically sealed systems — which are usually considered by end users as less likely to have issues with potentially leaking refrigerant.


 A2L racks — Similar to multi-scroll HFC systems already used in the UK for many years, A2L racks are becoming established as currently viable alternatives for stores from 300 to 2,000 m² that should also be compliant with anticipated future regulations. Offering low-GWP and lower flammability than R290, these gases are used in systems with smaller charges and have shown to reduce both energy consumption and total equivalent warming impact (TEWI). Manufacturers and system designers are successfully mitigating flammability risks via close attention to incorporating appropriate safety measures into these systems. By adopting a similar architecture to current HFC systems, operators can complete a sustainable, efficient and cost-effective refrigeration migration without having to significantly disrupt existing maintenance standards or store layouts.


 R290 chillers — Another natural option on the rise is the use of R290 chillers, which have been developed to service a store’s entire MT load. Indirect chillers often use R290 as their


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primary refrigerant — contained only in the chiller — and a glycol secondary refrigerant provides the cooling. If accessibility to the system is controlled, these chillers can use a higher refrigerant charge and cover a wide range of MT capacities. While this system is considered to be compliant with anticipated future regulations, its main disadvantages are the absence of an LT option, and some experts believe that these secondary systems are usually less efficient.


Options for smaller retail segments If we consider even smaller convenience formats — such as city stores, independent grocers and other express offerings — the challenges of costs increase. Within them we see similar architectures to those described above, but also the use of many smaller racks or factory-built, packaged units. Not only are smaller CO2


units becoming more


affordable, the gap between them and their HFC equivalents is likely to close further in the future. We are also likely to see the introduction of new variants in this market as well, such as packaged condensing units for LT and MT applications with A2Ls.


Regardless of the retail format, size or


segment, the pace of the transition away from HFCs is quickening. Since the early phases of the refrigerant transition, Emerson has partnered with equipment manufacturers and end users alike to design and develop future-oriented, low-GWP refrigerant technologies. From our wide range of energy-efficient compressors, flow controls and smart electronics to fully integrated packaged systems, we’re helping our customers transition to sustainable refrigeration strategies that align with their unique facility requirements and business objectives.


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