Carnot case studies proving CO2 is clear answer to R22 phase out

By Robert Davidson, Oct 19, 2015, 16:59 2 minute reading

Carnot Refrigeration presented four case studies in shecco’s GUIDE to Natural Refrigerants in North America, demonstrating the vast appeal of CO2 as a prime replacement for R22, including office server rooms and retail food applications.

As the special supporter of the GUIDE to Natural Refrigerants in North America - State of the Industry 2015, Carnot put forward four examples of their recent installations in North America using CO2 refrigeration. The two case studies presented below illustrate the virtues of replacing the moribund R22 with R744, in terms of environmental compliance and energy efficiency.

Carnot’s innovative CO2 system keeping Bell Canada’s servers cool

In 2012, Carnot was approached by telecommunications company Bell Canada to replace the R22 refrigeration system used in its server rooms, located in Ottawa, with Carnot’s Aquilon CO2 transcritical system. To ensure an optimal product, the development of the system involved close collaboration between the engineering departments of Bell Canada and Carnot Refrigeration.

This resulted in a construction that prioritised ease of maintenance, meaning all parts and equipment could be maintained from the front of the system as well as being able to be withdrawn from the front of the machine. Other key components of the 105kw cooling capacity system include:

  • Two semi-hermetic reciprocal compressors
  • Integrated control system
  • Stainless steel piping

The system also integrates Carnot’s patented Rain Cycle technology, which allows for continual refrigeration in the room without using the compressors, operating when outside conditions permit.

Results aquired between October 2014 – April 2015 reveal the system is functioning beyond expectations. The total electricity consumption during the period was 20,191 kWh all the while maintaining a server-room temperature of 25oC. The results also indicate the effectiveness of the Rain Cycle technology, with the free cooling functioning 95% of the time, meaning the system relies on its compressors only 5% of the time, saving significant energy.

Transcritical CO2 system as replacement to R22 at Alexis-Nihon Plaza

Carnot was tasked with replacing two old R22 systems with a CO2 transcritical systems with a capacity of 400 kW at Atwater supermarket in Montreal. The system designed was divided into three equipment parts: the transcritical section, the subscritical section and a gas cooler.

The transcritical section consists of eight semi-hermetic reciprocal compressors and integrated control. The subscritical section consists of two tanks, three semi-hermetic reciprocal compressors and integrated control, while the gas cooler has eight very quiet fans. Overall, the system incorporates two direct heat recovery circuits and a heat recovery system for domestic hot water, further saving energy and costs.

Preliminary numbers from the installation at the Alexis-Nihon Plaza show that this type of equipment will bring savings of around 10% per year in electricity usage alone in addition to heat recovery from the compressors used to heat the store, further reducing costs.


By Robert Davidson

Oct 19, 2015, 16:59

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