compact Kältetechnik, a Dresden, Germany-based refrigeration manufacturer, has extended its *carbo-Box line of transcritical CO2 condensing units, originally designed for medium-temperature applications, to deep freezing.

The units are designed to serve cold rooms and display cases in small food markets and to extend existing systems, said compact on its website.

Launched in 2018, the medium-temperature (-10°C/14°F evaporating temperature) units deliver cooling capacities ranging from 8.8 to 16.5kW (2.5 to 4.7TR) in three models. The new deep-freezing units (-30°C/-22°F evaporating temperature) cover a cooling demand of 9.6 to 20kW (2.7 to 5.7TR) in four performance classes. Evaporation temperatures are available between  -26°C/-15°F and -38°C/-36°F for a wide range of applications, enabling the highest possible evaporation temperature to save energy.

compact describes the *carbo-Box as “a plug-and-play complete system” ideal for “small cooling points with only one temperature level.” It is designed for outdoor installation, “so that no additional space is required inside the building.”

The heart of the *carbo-Box, said compact, is a frequency controlled transcritical two-stage compressor; only one is needed, rather than two. “This reduces the space requirement within the housing enormously,” the company said.

Another efficiency-increasing measure is the use of a medium-pressure separator with internal heat exchanger. This subcools the liquid refrigerant in the receiver and superheats the suction gas before it enters the compressor. “Even with very long liquid lines, the subcooling prevents unwanted vapor formation in the liquid phase,” said compact, adding that the superheating of the suction gas “protects the compressor from liquid inflow and guarantees safe operation of the system.”

Superheating also enable the stable operation of the system due to the higher final compression temperature, which means a larger average temperature difference with the ambient temperature. This “drastically improves the heat dissipation/rejection of the gas cooler and desuperheater,” said compact. “The cooling capacity always remains constant even in very hot summer temperatures.”

Global customers

compact’s marketing area is mainly Germany, Austria and Switzerland, though it’s equipment is also installed in Norway, the Netherlands, and areas outside of Europe, including China.

compact offers other types of CO2 systems, including racks, heat pumps and chillers, with applications for supermarkets, hypermarkets and warehouses. It also offers systems using ammonia/NH3 (R717) and propane (R290). In 2020,

approximately two-thirds of its sales  came from products using natural refrigerants.

“This trend has been growing strongly in recent years,” the company said. “This is one of the reasons why we have expanded our product portfolio in the field of CO2 solutions and developed standard solutions for faster delivery times.” But the company also offers customized solutions as well.

compact noted that government subsidies may be available for natural refrigerant systems, “which is why system technology with natural refrigerants is not necessarily more expensive.”

compact’s production and CO2 training facility can be viewed here and here.

“Even with very long liquid lines, the subcooling prevents unwanted vapor formation in the liquid phase.”

compact Kältetechnik

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Author Michael Garry