The conversion to new refrigerants generates 40% of energy savings CITY2 case study with RC group – Belgium

Tuesday, 28 July, 2015
While conversion to alternative refrigerants and compliance to F-Gas directives in Europe require heavy investments, end users have real opportunities of very quick returns on investment

At first sight, renovating an air-conditioning systems is expensive. While conversion to alternative refrigerants and compliance to F-Gas directives in Europe require heavy investments from the OEMs and component manufacturers, end users have real opportunities of very quick returns on investment. Because the new air conditioning systems will also be using more modern and energy efficient cooling technologies. That is what City 2, the 51,000 m² and largest urban shopping centre in Belgium experiences.

Located in “Rue Neuve”, City 2 is in the heart of the city of Brussels. From more than 35 years, City 2 attracts a loyal audience with nice architecture, natural lighting through two glass roofs that creates a pleasant surrounding environment, all while being independent of external climate. This pleasent environment keeps the space not too hot in the summer and not too cold in the weather.

The situation could seem familiar for many HVAC installers. In 2012, Cofely Axima noted that City 2 chillers could cause problems in the short term because they were still using R22 refrigerant. The R22 refrigerant has reached the end of an era, and is no longer allowed to be used as of January 2015. 

“It’s astonishing that there are still many air conditioning systems in Europe using R22 with a high risk of immediate stop. This leaves the system with no refrigerant available for replacement and with a probability of refrigerant loss. This scenario could lead to the negative consequences for the cost and environment” says Jeremy Holef, Aircotech SA Sales & Technician.

This has not been the case of City 2. The end user, the installation company and the importer met in 2012 to find a solution before having any service complications.
In the first phase, five of the existing chillers with R22 refrigerant have been replaced with four air cooled liquid chillers UNICO TURBO 590 T2 Y5 (550kW – R134a) equipped with Danfoss Turbocor® compressors. “The chillers substitution matched the City 2 commercial centre energy reduction general plan, so the energy consumption of the new equipment was carefully monitored. As expected the results were particularly good.” says Jeremy Holef (Aircotech SA Sales & Technician). “The proposed solution is exceeding the expectations of the final user. The new RC Group Turbocor chillers are so energy efficient that the return of the investment is within two years and that the owner of the building decided to replace the remaining two chillers to save more on maintenance issues with two UNICO TURBO FL 680 T2 VT6 earlier than in the investment plan “ he adds.

These units are the newest version of UNICO TURBO and are available in cooling capacity range from 280 to 1500kW. UNICO TURBO FL is an air-cooled chiller equipped with Danfoss Turbocor® oil-free centrifugal compressors with magnetic levitation bearings. The high quality of the different components and the design of the unit increased the lifetime of the system. The single pass evaporator or counter current evaporator is replaced by a flooded evaporator in this version. The evaporation temperature is only 1 degree higher than the liquid outlet temperature. A lower temperature differential means higher energy savings.

Thanks to the highly efficient devices installed in City 2 we plan to obtain 35% energy savings” says Holef. “Today, six units replace seven old larger and noisier units that provide more overall efficiency of the installation. All the UNICO TURBO units working together at part-load lead to produce 5% additional energy savings. It’s absolutely possible to realize savings by intelligently selecting the units.

City 2 is located in the centre of Brussels. “The sound emissions of the chillers were an important parameter for the selection of the new units“ says Jeremy Holef. “Our UNICO TURBO has good results in this area. We have provided a low noise version with 60dB(A). We obtained satisfactory results thanks to the installation of Danfoss Turbocor compressors in a soundproofing box and credits the frequency regulator for unabling the compressor work in the most silent mode as much as possible.” 

Another improvement of the A/C system is the microchannel condensing coil replacing the standard aluminum-copper coil. This means a larger exchange area and a more efficient energy transfer. The use of a microchannel condensing coil produces a significant weight reduction of the unit and a substantial reduction of the refrigerant volume. The microchannel condensing coil is also treaded in this application with an epoxy coating (TK PRO) to protect against aggressive atmospheric agents in this very high urban traffic area 24h per day.

The next step is the conversion to HFO 1234ze refrigerant with the Go Green Chillers, the new RC Group Ecorange Chillers featuring Danfoss Turbocor TG oil-free centrifugal compressors: the fastest way to meet the F-Gas requirements and take the environmental leadership. RC Group makes use of refrigerants innocuous to the atmosphere. The HFO1234ze results to be an excellent solution for the replacement of R134a thanks to its high environmental compatibility linked to high energy efficiency. Another benefit is its higher critical temperature which allows rating at much higher condensation temperatures while retaining a good thermodynamic efficiency. Go Green chillers range from 260-1260 kW.

Innovation is a priority for the Italian Manufacturer RC Group. RC Group was the first Italian manufacturer to introduce the free-cooling in its range. This is why RC Group is an ideal partner for market introduction of air and water-cooled chillers equipped with Danfoss Turbocor® compressors. Aircotech SA is RC Group subsidiary in Belgium.

Pre-existing A/C system:
7x air cooled liquid chillers equipped with screw compressors (5x510kW; 2x700kW). R22 refrigerant charge.

New A/C system:

  • Cooling Capacity: 3600 kW
  • 6x air cooled liquid chillers equipped with Danfoss Turbocor® oil-free centrifugal compressors with magnetic levitation bearings  
  • 4x UNICO TURBO 590 T2E Y4 manufactured by RC Group (4x550kW)
  • 2x UNICO TURBO FL 680 T2 VT6 manufactured by RC Group (2x680kW)