30 September 2020
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The Aurora pack from Arctic Circle
As it prepares to celebrate its 35th anniversary, Hereford-based Arctic Circle continues to lead the way in innovation with its latest refrigeration solution.
Arctic Circle’s latest LT-only transcritical booster system, known as the Arctic Aurora, delivers up to 300kW of cooling at -30°C SST. The pack was developed and created with JD Cooling for a world-renowned food processing company in the UK and is now up and running in its new home in the east of England.
Mark Culley, Managing Director, of the JD Cooling Group, said: “Arctic Circle was the natural partner to choose to fulfil the exacting requirements of our client, a leading global food manufacturer. As a result of this collaboration we have developed a truly class-leading product, with the correct level of detail and specification for the industrial end user’s needs. We are proud that even during the height of the Covid-19 outbreak, we were able to deliver this turnkey project on time and on budget.”
The development of the Arctic Aurora was conceived and designed by Arctic Circle’s engineering design team who have consistently delivered pioneering refrigeration to the market for 35 years.
The Arctic Aurora is a standalone low temperature natural refrigeration solution optimized for efficiency with a dynamic resilience control. The pack incorporates a patent pending control strategy which ensures the two compressor stages work seamlessly together to guarantee that the compressors are always available to run. The result is uncompromised performance and high resilience; the optimized operation protects the compressor by recognizing low superheat conditions and acts accordingly. This model of the Arctic Aurora incorporates BITZER 6TME-35K-40P compressors, the first non ECOLINE+ Varistep models in the UK.
Radically rethought
Arctic Circle Business Development Manager Patrick Knight said: “We saw an opportunity to bring our existing CO2 transcritical platform to the industrial cooling market. Using CO2 in place of other refrigerants can reward the end user with significant capital cost savings and significantly reduced direct carbon emissions. As a natural fluid with a low global warming potential, ongoing costs of CO2 as a refrigerant are largely unaffected by the F-Gas phase down and will continue to remain very low for the foreseeable future.
“All things considered, the total cost of ownership of such systems when compared against the status quo can be very attractive. As market leaders of CO2 refrigeration system design and manufacturing in the UK, this product has its foundations in our existing expertise but has been radically rethought to match the demands of the industrial and food processing sectors.”
Liam Grice, Lead Electrical Project Engineer at Arctic Circle, said: “Schneider PLCs were used for both the primary and backup controllers for this project. The flexibility of the PLCs meant that bespoke software could be created within Arctic Circle; optimising the unique requirements of the LT Only transcritical booster system.
“Resilience was important to the customer so the pack was configured with the N+1 format. The bespoke software meant the number of compressors running at a given time could be limited whilst equalizing the run hours for even wear and automatically starting a spare compressor if a fault occurred.
“To aid commissioning and maintenance, 7” colour HMIs were used displaying a full pack schematic with operating conditions. For external communication sharing pack information the MODBUS standard was used.”
Exciting year
The Arctic Aurora has been extensively system modelled using Arctic Circle’s bespoke software, which has been developed over the course of six years in collaboration with customers, suppliers and partners. It incorporates a verification stage where real time energy consumption of the system is collated and compared against theoretical modelling. This allows for the efficiency data to be as fluid and true to real life as possible. The refrigeration industry has been pressured to ensure that energy consumption remains low and system verification modelling shows that the pack offers a 6% reduction in energy consumption against a typical transcritical system.
The industrial specification means the system has been designed with a number of additional provisions to ensure it is fit for purpose. These include additional liquid holding capacity, increased design pressures, extra-large suction accumulators to protect against liquid flood back or condensation within the suction line, full back-up PLC controls and instrumentation and back-up high pressure control valve and flash gas control valve.
2020 is proving to be an exciting year for Arctic Circle, with the appointment of Mike Gittoes as Managing Director at the beginning of April and the celebration of its 35th anniversary this November. The company believes the Arctic Aurora to be an outstanding demonstration of its proven ability to drive innovation in the market.
Brains and brawn behind BITZER's ECOLINE
BITZER compressors for transcritical CO2 applications have been used around the world since 2004 with great success. The six-cylinder units employed in the Arctic Circle application are from BITZER’s ECOLINE semi-hermetic range, designed for high efficiency transcritical CO2 projects.
Available in 2-, 4- and 6-cylinder versions, they are said to be suitable for use in a wide range of applications, delivering excellent reliability and environmental protection. The latest generation employs a new housing design with optimised suction and discharge gas channels and high efficiency motors.
Key technical features include:
- The capacity range covers displacements from 3.3 to 38.3cu m/hr. The six-cylinder units specified by Arctic Circle include the largest in the range, the ECOLINE 6CTE-50K. Powered by two motors, this behemoth has a cooling capacity of more than 81kW (at -10°C), and weighs in at over 240kg.
- Energy efficiency is a key design priority. To help optimise this, the units include:
- suction gas-cooled motors;
- cylinder heads with separate, thermally isolated high and low pressure chambers;
- a highly efficient valve design.
- Use of the latest Line Start Permanent Magnet (LSPM) motors increases motor efficiency and seasonal performance. A strong seasonal performance is important in reducing both Total Equivalent Warming Impact (TEWI) and the end user’s operating costs. As a result of performance improvements in the most common operating range, LSPM motors can increase annual efficiency by up to 14%.
- ECOLINE units have a high pressure housing that does not require the use of a bottom plate, enabling maximum permissible pressure levels of up to 160Bar on the high side, and 100Bar on the low side of the system.
- To enhance reliability and extend working life, compressors run on multi-layer bearings and wear-resistant drive gear.
- Units are designed to optimise oil management to ensure smooth operation and extend working life. This also helps minimise noise and vibration.
The BITZER IQ Modules used on the project carry out multiple tasks, acting as an intelligent overseer, monitoring, protecting and analysing compressor operation.
Important performance parameters are monitored in real-time. These include motor and discharge gas temperature, high pressure switch and oil level and pressure.
It provides early warning of potential problems, flagging operating conditions approaching specified safe limits. Technicians and end users can access stored logs of alarms and warnings, with a full archive of run-time and load statistics for more detailed analysis.
Kevin Glass, Managing Director of BITZER UK, said: “Carbon dioxide systems, and transcritical applications in particular, require compressors with a combination of strength, reliability, efficiency and control. The ECOLINE range has proved its abilities in all of these key areas. The addition of the IQ Module adds the other vital ingredient – intelligent oversight. It is a powerful package that delivers for contractors, end users and the environment.”
