Danfoss Store CO2
Danfoss 'Smart Store' in Nordborg, Denmark. Photo Credit: Danfoss.

Danfoss ‘Smart Store’ Helps Determine the Most Energy-Efficient Way to Integrate CO2 Technologies

Ejnar Luckmann, the store’s Technical Manager, gave ATMOsphere an exclusive tour of the smart store.

Last summer, Danish component manufacturer Danfoss opened a “smart store” next door to its headquarters in Nordborg, Denmark, which provides an opportunity to showcase its latest CO2 refrigeration technology and conduct R&D. The store shows what’s possible with an integrated CO2 system.

The smart store is a working supermarket with 813m2 (8,751ft2) of floor space and a 240m2 (2,583ft2) machine room, which houses the R&D lab, known internally as the application development center (ADC). A major focus of the store is energy savings and efficiency, and to that end its integrated CO2 system provides refrigeration, heating and cooling. In addition, there are 100kW solar panels installed on the roof that supply most of the store’s electrical power.

Ejnar Luckmann serves as the store’s Technical Manager, and he gave Marc Chasserot, Founder and CEO of ATMOsphere, a tour of the ADC, highlighting the energy savings realized in the year since the store’s opening and possible further system integrations. ATMOsphere is the publisher of NaturalRefrigerants.com.

Heat producers

Luckmann noted that when it comes to heating, the smart store has been self-sufficient. It is equipped with Danfoss’s heat recovery unit, which supplies comfort heating and domestic hot water. The company’s heat recovery unit was nominated for the ATMO 2023 Innovation of the Year Award for North America as part of the 2023 ATMO America Summit.

Excess heat is sold to the local district heating network, and Luckmann said sales have been brisk.

“Since its commissioning in May 2023, the store has bought 87kWh of heat ‒ required for the system startup ‒ and sold over 15,000kWh to district heating,” Luckmann said.

He noted that the system produced one and a half times the heat needed by the store and the ADC in a test conducted during the winter with a −6°C (21.2°F) nighttime temperature and a roughly 0°C (32°F) daytime temperature.

“Being able to create energy at very low temperatures to get the highest performance in our area is what it is about,” Luckmann said. “The CO2 system is a heating machine and a refrigeration system.”

An optimized system

The Danfoss store contains two CO2 refrigeration racks: a standard one and an “energy pack” with all the “bells and whistles,” including parallel compression and ejector technology, Luckmann said.

The energy pack covers refrigeration, heating and comfort cooling in one rack, with connections to a ground-source heat pump and a Danfoss heat recovery unit. The store’s medium-temperature cooling capacity is 30kW (8.5TR), and its low-temperature capacity is13kW (3.7TR).

In addition, a heat recovery wheel in a standard air handling unit recovers heat from the air sucked out of the supermarket.

According to Luckmann, the efficiency of the wheel runs a little above 80% heat recovery, adding that it is not about optimizing the wheel but rather streamlining the entire system.

A total of 50 electrical and heating meters monitor and help optimize the store’s energy usage, with digitalization providing an overview of all the applications. “Optimization is a compromise between the applications and not a suboptimization of one application,” he added.

Suitable to every climate

The Danfoss smart store is equipped with a roof-mounted adiabatic gas cooler despite the absence of high ambient temperatures in Nordborg, with summer temperatures rarely climbing above 26.7°C (80°F).

Luckmann explained that the store experiments with different technologies for different environments. “In a hot climate, an adiabatic gas cooler, using a little bit of water, gives 5‒7K (5‒7°C/9‒12.6°F) extra cooling; CO2 systems operating in countries closer to the equator need that cooling.”

The store contains Danfoss CO2 technologies for colder and hotter climates than those in Denmark and for different-sized stores, including hypermarkets and smaller grocery outlets. “We are showcasing it here, and we can bring customers from around the world to have a good dialogue about what makes sense for them,” Luckmann said.

Additional tech

According to Luckmann, Danfoss has determined the appropriate size for a battery storage unit to add to the system based on the energy stream data for the year. “Battery storage will allow us to optimize electrical energy flow, storing it at low prices and offloading it at high prices,” he said, adding that the company plans to build it this year.

Other technologies in the works include cold and heat storage, car charging stations for electric vehicles and hydronic heating/balancing.

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