UPDATE: Ejectors achieve 15% energy savings in commercial refrigeration system

By Janet Thompson, Mar 10, 2014, 11:40 2 minute reading

At the supermarket Migros Bulle in Switzerland, Frigo Consulting’s first transcritical CO2 system operating with ejector technology has registered an energy efficiency increase of 15% compared to traditional CO2 systems. In total, the system generates 150 kW of cooling capacity. + VIDEO

Since July 2013, the first transcritical CO2 system with ejector technology, designed by Frigo Consulting, has registered 15% energy savings by reduced internal losses. Thanks to the efficiency of the systems, 60,000 kWh of electrical energy can be saved per year, the equivalent of a 9,200kg CO2 reduction. The data already collected provides useful information for further optimizing the CO2 refrigerating system and the ejector technology.

How the system works

The CO2 circulates in the closed circuit, whereby it is compressed and expanded at different pressure levels. When compressing CO2 with compressors, energy is absorbed. When the CO2 is expanded, energy is released. Until now, this energy has not been used; however, with an ejector, this unused energy is used to relieve the compressors.

The ejector has no movable parts; its relatively simple integration is based on standard components and thereby ensuring a high operational safety and low investment costs.

Liquid CO2 in the suction line of the medium pressure compressor is separated in the low pressure receiver. From there, the ejector, which is powered by the until-now-unused-energy, pumps the liquid CO2 back to the medium pressure receiver. From there, the CO2 is again brought to the evaporators. The ejector makes is possible to forgo the complete evaporation of CO2 in the evaporators without endangering the compressor through a sudden surge of liquid. This means that the evaporation temperature can be increased and energy can be saved.
It is only a matter of time until ejectors have their breakthrough on a large scale and significantly increases efficiency of transcritical CO2 refrigeration systems, particular in commercial refrigerating systems in southern regions,” says Jonas Schönenberger, Frigo-Consulting Ltd.

A collaborative effort

This milestone in energy efficiency was achieved with the trust of Migros Neuchâtel-Fribourg and the support of the Swiss Federal Office of Energy (SFOE). For over a year, engineers and refrigeration experts from Frigo Consulting, SINTEF, Enex and Alpiq InTec West worked together on the implementation of the ejectors.

About Frigo Consulting

Founded in 1988, Frigo Consulting has been mainly active in the fields of commercial and industrial refrigerating systems with a focus on sustainable engineering as well as subcritical and transcritical CO2 systems. The company, with its head office located in Bern, Switzerland, offers support in design and engineering of innovative refrigerating systems and implementing them into overall facility concepts.


By Janet Thompson

Mar 10, 2014, 11:40

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