How CO₂ scroll technology boosts retail refrigeration


07 April 2022
Copeland ZTW variable speed scroll compressors are designed for use in CO₂ medium temperature refrigeration systems

With its New Cool initiative, Emerson promises nothing less than a reinvention of CO₂ refrigeration, combining reduced system complexity with significant energy efficiency, reliability and sustainability benefits. Eric Winandy, Director OEM Solutions Development and Sales, explains the technical details.

Emerson has put major research and development effort into advancing sustainable refrigeration through Copeland scroll technology for transcritical CO₂ refrigeration systems. CO₂ itself has been well-established as a refrigerant for decades, so what's really new about The New Cool?

It truly is a major leap in technology. In short, our innovative technology removes the complexity previously associated with CO₂-based refrigeration systems, making them easier to manage and lowering costs. This not only renders the natural refrigerant affordable, but also lays the foundation for highly flexible, future-proof CO₂ refrigeration systems that meet regulatory requirements and allow for particularly sustainable operation in all climates. All market participants benefit from the drastic reduction in system complexity that comes with The New Cool: OEMs can develop simple and cost-efficient CO₂ booster systems, installers will find the new CO₂ system architecture much easier to work with and end users are guaranteed to get future-proof technology with optimal energy efficiency, regardless of the climate.

What sets your CO₂ technology apart from others?

The main difference is the use of a new generation of scroll compressors to replace the piston compressors commonly used in commercial CO₂ refrigeration. Our newly developed compressors are equipped with an innovative injection technology for flash gas management, which we call dynamic vapor injection (DVI). It is complemented by a suite of advanced electronics, at the heart of which is the new Copeland XC Pro CO₂ scroll controller that has been specifically designed for CO2 scroll booster applications.

The XC-Pro system controller enables a plug-and-play-like solution with pre-configured and pre-tested components

This combination brings numerous benefits. DVI renders a separate parallel compressor unnecessary and allows for a reduced footprint and weight of the rack. This in turn facilitates the design of CO₂ booster systems and their installation in confined environments such as urban retail stores in pre-existing structures. In such environments, another advantage comes into play: due to their continuous compression process, our CO₂ scroll compressors also run much smoother and quieter than piston compressors, only producing low noise emissions that are further reduced by the enclosure design. In addition, our scroll compressors’ extremely low vibration level eliminates the risk of piping ruptures – a technical advantage that applies to all installations regardless of location. 

In this context, it is also worth mentioning that our CO₂ scroll solutions are fully compatible with heat recovery through the XC Pro controller, offering the ability to supply the energy required for store or domestic hot water heating. This is an important argument for store owners as it leads to significant energy savings.

You highlighted Dynamic Vapor Injection technology as one of the key innovations. How exactly does it improve flash gas handling in conjunction with the scroll compressor?

Using Dynamic Vapor Injection, flash gas is directly injected into the intermediate stage of the continuous compression process of the scroll, while the controller adjusts the injection pressure to optimise system performance. To prevent the injected gas from flowing back into the flash tank, our engineers have developed a solution with a dedicated check valve. Compare this to semi-hermetic compression: here the flash gas is either injected at the suction side, which is simple but less efficient, or the flash gas is managed by an added parallel compressor, which is efficient but also more expensive. With our DVI technology, there is no need for an additional parallel compressor to handle flash gas, while its efficiency is even higher. Thanks to this simplified system architecture, CO₂ flash gas can be compressed in a very cost-effective and efficient way, allowing a single booster design for all climates.

The Copeland CO₂ scroll booster circuit features compressors equipped with innovative dynamic vapor injection technology (DVI), rendering a parallel compressor unnecessary

To what extent does the elimination of parallel compression and reduced complexity create new opportunities for system design? Can you give some examples?

Think of an original equipment manufacturer (OEM), for instance. With our technology, they only need to develop a single system design that can be used in all climates, as the benefit of parallel compression is integrated in our DVI technology. Thanks to eliminating the parallel compressor and its drive, the OEM also needs fewer system components such as related piping, heat exchangers, pressure switches and oil control, so both development and material costs are reduced. The administrative overhead is also decreased because the OEM needs fewer bid specifications, fewer piping and instrumentation plans, fewer quotes from suppliers, fewer parts to order and fewer maintenance schedules. They only have to select from a small number of perfectly matched components to be able to offer a wide range of planning options suitable for all target applications. In fact, this type of standardisation greatly facilitates system design not only at the OEM level – its benefits ultimately extend to installers and end users as well.

Your newly developed CO2 scroll technology replaces piston compression widely used in CO2 booster systems. Apart from cost and efficiency, what other specific advantages does this offer?

Our scroll compressors – operating at twice the speed of piston compression – deliver more capacity per volume. The scroll compressor footprint is about half that of the equivalent semi-hermetic. Combined with the elimination of the parallel compressor, this allows the OEM to reduce the size of the booster rack, creating more vending space for the end users.

What are the benefits of using this CO₂ scroll technology with your new, soon to be launched refrigeration units?

Emerson’s new range of refrigeration units translates the potential of Copeland CO₂ scroll technology into real-world benefits for retailers. It allows for highly flexible planning and installation thanks to the units’ light weight, compact dimensions and their unique modularity concept. These characteristics make them particularly suitable for urban environments, as well as for refurbishments where space is limited. 

In addition, the need for high energy efficiency is addressed. Complementing DVI technology and advanced controls, dedicated variable speed compressors with specific high efficiency Brushless Permanent Magnet (BPM) motors and drives also help to minimise energy consumption. Using these motors allows for a wide range of capacity modulation and for the system to adapt to changing cooling needs with reduced on/off cycles. Thus, it always operates at optimum efficiency, regardless of daily load fluctuations or seasons.

Another important advantage is that these units contribute to the goal of sustainability. Thanks to their high energy efficiency, they comply with the European Ecodesign Directive and are not affected by the F-Gas regulation due to the use of the natural refrigerant CO₂. For retailers, this creates legal certainty and future viability.

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In connection with The New Cool, you also emphasise that your new CO₂ scroll refrigeration units are applicable even for the warmest climates, with guaranteed uninterrupted operation up to 44°C ambient temperature. How do you ensure that, technically?

The superior operational reliability of our CO₂ scroll products is achieved by combining dynamic vapor injection with advanced controls to operate CO₂ easily, safely and reliably in all climates. Our innovative control concept includes unique features such as envelope control and fault detection, as well as diagnostic functions that ensure reliable operation and reduce the risk of food spoilage. The fact that The New Cool refrigeration units feature high standstill pressures provides additional safety and a time buffer for operators during downtime periods. Last but not least, the use of our DVI technology enables operations at high ambient temperatures and eliminates the need for an adiabatic cooling system.

Another aspect Emerson highlights with regard to the refrigeration units is the modular design concept. What does that refer to exactly?

It is our answer to challenges retailers face in meeting a wide range of requirements, especially in urban areas where they deal with demanding installation conditions, space constraints and strict noise regulations. Emerson’s Copeland CO₂ scroll technology has been designed with a strong focus on small and medium-sized stores, ensuring units are lightweight, compact and optimised for silent operation. To maximise flexibility for the target application, our concept allows refrigeration units to be installed packaged or split, indoor or outdoor. A gas cooler that can be positioned horizontally, vertically and stand-alone opens up further installation alternatives. Combined, the options provided by our modular design concept add up to maximum flexibility in building integration.

You also offer your technology as a complete solution that includes the compressor and drive, plus electronics. But in general, system manufacturers already work with a dedicated electronic supplier/system controller – so what’s in it for them?

The XC-Pro system controller is one of the main advantages of this CO₂ solution package for OEMs, as it enables a plug-and-play-like solution with pre-configured and pre-tested components. All integrated components, such as the scroll compressors with DVI and their drives, are already paired by Emerson to enable a faster time to market, while components like the high pressure or the bypass valve – to name just a few – are already optimised for efficient and reliable interaction managed by the XC-Pro system controller. This eliminates a time-consuming configuration of the system controller with the system components, significantly reducing development and design time for the OEM. In addition, the system controller can be easily integrated into any store’s Building Management System.

Does your new technology also represent a fundamental change in Emerson's commercial refrigeration portfolio, shifting the focus from propane to CO₂ or even abandoning propane altogether? 

In commercial refrigeration there is no “one solution fits all”. In fact, applications can vary widely, depending on shop format and system architecture, climate, neighbourhood issues, skills and strategies. That is why we support all customers regardless of the refrigerant – our goal is to provide them with a reliable, efficient and future-proof solution that meets all regulatory demands in terms of sustainability. The non-flammable R744 combines favorable properties like a low global warming potential (GWP) and low toxicity with a high heat transfer coefficient, but R290 also offers many advantages like a low working pressure and high efficiency. Hence, our portfolio will continue to contain CO₂ and propane products. Both are viable options for sustainable refrigeration. However, the selection of the appropriate refrigerant must always be tailored to the customer's requirements. In the long term, all market participants will need to shift to refrigerants with a low GWP.

You have already outlined the benefits of CO₂ as a natural refrigerant. Does your unit’s technology also meet the growing sustainability demands in other areas?

Yes, it does – in fact, the new refrigeration units take sustainability to another level. They use smart electronics to increase energy efficiency by continuously matching the cooling capacity to the actual demand. The heat recovery option is another important way to reduce energy demand: because it recovers energy that would otherwise be wasted and makes it usable for heating or hot water supply, it helps to reduce the overall energy demand of the respective store. But our efforts go beyond the CO₂ footprint. The new CO₂ refrigeration units not only contribute to reducing power consumption, but also manage to reduce noise emissions. The advantage of low vibration and the scroll compressors’ low noise level is further enhanced by the compressor compartment’s special sound insulation. In addition, the latest generation of EC fans help to keep noise emissions low. Finally, redundancy of compressors and fans, intelligent controls with fault detection and communication with the building management system ensure reliable 24/7 operation and help to keep food quality at a high level, while avoiding food spoilage.

When will your new CO₂ compressors and refrigeration units be available to the market?

The introduction of our Copeland CO2 scroll compressors has already started in Europe. It will gradually be extended globally. Our new range of refrigeration units featuring DVI technology and smart electronics will be launched soon and will be limited to the European market.

Let’s look into the future: to what extent is your technology prepared to make digitalisation applicable to refrigeration, for example through IoT and cloud-based data analysis?

Digitalisation is already an essential element of The New Cool. We aim to provide customers with system solutions that can be operated, monitored and maintained quickly, easily and productively with maximum reliability and efficiency. For us, this means collecting, analysing and evaluating operational data from the system and its components, to take action to improve system efficiency. We are IoT-ready and provide data in an open, non-proprietary way.

Emerson is well equipped for this task. We not only design and manufacture components, but also develop the controls and algorithms needed to turn mere data into actionable information. For us, digitalisation is ultimately a means to continuously improve our customers’ refrigeration systems, their performance and reliability and to help them achieve their business goals.

Eric Winandy has 30 years of experience in air conditioning and refrigeration research and applications. He has authored and co-authored papers and articles on compressors and applications topics, and he is reviewer of the International Journal of Refrigeration and a member of the scientific committee of Gustav Lorentzen Conference on natural refrigerants.

He is also an active member of the HVAC&R professional associations, ASERCOM (Association of European Refrigeration Compressor and Controls Manufacturers), IIR (International Institute of Refrigeration (IIR), IoR (Institute of Refrigeration) and EHPA (European Heat Pump Association).