R744.com on location at Carnot Refrigeration NH₃/CO₂ installation in Québec

With the aim of minimising environmental impacts and reducing operational costs, Carnot Refrigeration provided the Courchesne Larose warehouse with an ammonia/CO₂ refrigeration system that involves innovative new technologies, such as hot gas defrost and heat recovery.

The installation is also featured as one of the case studies in the publication "Guide 2013: Natural Refrigerants - Market Growth for North America" that was recently published by shecco.

Discharge gas heat recovery leads to significant energy savings

The hot gas defrost offers the possibility to heat the docks and all other areas of the warehouse as needed, avoiding additional energy expenditure and the need to use additional mechanical equipment (pumps, loop glycol, heaters, etc.).

The NH₃/CO₂ refrigeration system is designed to recover direct heat from the discharge gases of the CO₂ compressors to fuel recovery coils and to heat the ambient air of offices and warehouse spaces, such as the shipping dock and work shop, which require heat. This option provides recovery capacity up to 8 times greater than the use of an intermediate loop glycol.

Key advantages of the NH₃/CO₂ system

With a surface area of 100,000 ft² (9,290 m²) and a height of 40 ft. (around 12 meters), the Courchesne Larose warehouse is able to accommodate over 2,000 tonnes (4,563,442 lbs) of food per day. It includes 22 ripening rooms for bananas, a main dock with 19 garage doors, and a banana dock with 3 garage doors. The temperature in the rooms varies between 0 and 15˚C (32 to 59°F).

Additional advantages of the Carnot Refrigeration technology include:

• Completely eliminates the use of HFCs and / or HCFCs
• Ammonia charge reduction without an energy penalty
• Reduces piping and insulation size by more than half and the related labour and material costs by 31.5%
• Reduces the use of paraseismic hangers and the structural need to support the pipes
• Provides full heat reclaim (if needed) for space heating or water heating (domestic or process)

TFC mode - Free Cooling

Using CO₂ by direct expansion in cascade with ammonia, allows the use of the TFC mode (free cooling) when the outside temperature is below 8°C. This mode is maintained for 4000 hours in the Montreal area. During the hours of TFC mode, NH₃ compressors remain completely stopped. These breaks increase the lifetime of the compressors, the lubrication system, and other components of the ammonia loop.

About Carnot Refrigeration

Established in 2008, Carnot Refrigeration offers integrated services for the design, manufacturing and installation of high quality and eco-efficient CO₂ systems for supermarkets, industrial applications and ice rinks. Carnot Refrigeration makes a conscious effort to design refrigeration systems and heat pumps that cut down on the use of polluting refrigerants. It has taken the lead in its field by creating high-efficiency refrigeration systems designed by specialised engineers and manufactured in an environmentally controlled plant or at a constraint-free site.