Technology innovations: integrated systems, parallel compression, ejectors

By Janet Thompson, Oct 25, 2013, 11:47 4 minute reading

Some of the major technical advances presented at ATMOsphere Europe 2013 were integrated systems, which can provide refrigeration, air conditioning and heat reclaim, parallel compression and the use of ejectors. Advansor, Carel, Green & Cool and Frigo-Consulting provided insight into these technologies, their application and efficiency results.

Both Advansor and Carel presented their newest CO2 technology development, an integrated system with parallel compression that meets all of a supermarket’s thermal needs by supplying refrigeration, air conditioning and heat recovery at ATMOsphere Europe 2013, which took place on 15 & 16 October 2013 in Brussels. Green & Cool and Frigo-Consulting also spoke about their experiences with parallel compression, which has shown higher energy savings compared to a traditional CO2 booster system, especially in high ambient temperatures. Frigo-Consulting further elaborated on its use of ejectors for optimising efficiency.

Advansor’s Swedish experience

Jens Kallesoe, Advansor’s Nordic Sales Manager, presented Advansor’s Sigma system, which provides refrigeration, air conditioning and heating for a new Coop Maxi store in Tocksfors, Sweden. It incorporates technologies such as parallel compression and heat pump function with artificial loads on the cabinets.
We can combine all thermal demands of the supermarket now in one system,” says Jens Kallesoe, Nordic Sales Manager, Advansor 

With no access to district heating, one of the store’s main specifications was that it needed to be self reliant for heating in the winter, meaning all the heat from the system would need to be reclaimed. To meet this challenge, Advansor installed two heat recovery units in the system. Efficient heat reclaim is achieved with parallel compression, which takes the gas directly from the receiver to the high-pressure side without using a gas bypass valve, and a false load evaporator. Since the parallel compressor is being used to gain heat, it has a better COP factor (heat COP of 3.2) compared to the LT or MT compressors. Kallesoe explained that with the artificial load, the store produces more heat than it needs and delivers the surplus heat for a district heating system for the local community.

The two systems operating in Sweden have shown 700kW of AC production capacity, which should fit the needs of every store, even in southern Europe, said Kallesoe. Today, Advansor has installed nine of these systems in Europe, seven of which include the AC evaporator and two of which only have the parallel compressor for high ambient temperatures.

Carel applies its controller to CO2 integrated system in Germany

Diego Malimpensa, from Carel, introduced a similar innovation, a system providing refrigeration, AC and heat recovery that can be controlled by a single controller, installed in a medium-sized supermarket in southern Germany. The integrated system features two MT compressors with a capacity of 60kW, one LT compressor with a capacity of 8kW, one parallel compressor with a 12m3/h flow rate, one heat recovery heat exchanger with 75kW and one air conditioning heat exchanger of 30kW. Using parallel compression and flash gas valve synchronisation, the system is optimised for warm climates.
We have an entire system that is managed by one single device. That means: lower installation costs; increased usability (one point of access); faster commissioning; and improved efficiency”, said Diego Malimpensa, Carel Industries 

Green & Cool’s latest CO2 developments

Stig-Göran Lind, Marketing Director for Green & Cool, provided an update of the company’s CO2 R&D progress on its ‘ECO’ products for warm climates. Latest developments include parallel compression, flash gas removal and an improved control system that can achieve a higher COP even in high ambient temperatures.

Ejectors and parallel compression by Frigo Consulting

Jonas Schönenberger from Frigo-Consulting presented a project at a Migros Bulle store in Neuchâtal-Friboug. In incorporating ejectors into the system with parallel compression, two of the key benefits compared to standard booster systems were that the evaporation temperature can be increased and part of the vapour can be shifted from the MT compressors to the parallel compressor, reducing the work load on the other compressors.

The system incorporates ejectors and a low pressure receiver, as well as a parallel compressor. The ejectors recover throttling losses in the system and allow liquid or vapour to be sucked out of the low pressure receiver and fed back into the medium pressure receiver. As a result, the superheat can be reduced to zero Kelvin and fed to the evaporators. The flooded evaporators show a much higher heat exchange efficiency and the evaporation temperature can be increased to approximately -1.5°C, a considerable difference from the standard booster system’s 8°C evaporation temperature.

Overall, the system has a MT cooling capacity of 120kW and a LT cooling capacity of 55kW. The measured efficiency increase thanks to the use of ejectors to recover throttling losses is 12% compared to a CO2 booster system with a parallel compression unit. The higher the ambient temperature, the recovery of the throttling losses increases, as does the potential to increase efficiency.

View presentations

Integrated CO2 booster for high-efficiency cooling, heating and air-conditioning by Jens Kallesoe, Advansor

CO2 integrated systems for warm climates by Diego Malimpensa, Carel Industries

Today and the future for CO2 technology by Stig-Göran Lind, Green & Cool

Advanced CO2 booster system for warm climates by Jonas Schönenberger, Frigo-Consulting


By Janet Thompson

Oct 25, 2013, 11:47

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