Ejectors bring CO2 to warm climates

ITALY: A collaboration between two of the refrigeration industry’s leading firms could lead to improvements on efficiencies of transcritical CO2 systems in warmer climates.

Controls and humidification specialist Carel has joined forces with Carrier Commercial Refrigeration Europe to develop a range of modulating ejectors. These, they say, could put an end to the concept of the “CO2 equator”, the until-now accepted geographical limit for the cost-effective deployment of CO2 systems in stores.

In addition to its energy-saving capabilities, the modulating ejector is also claimed to reduce installation costs and complexity, as it can continuously and instantly adapt to specific operating conditions.

Exploiting Venturi effect

The modulating ejectors are being unveiled for the first time this week at Atmosphere Europe 2016 in Barcelona in a paper being presented by Carel’s retail solutions business unit manager Diego Malimpensa.

While in-depth details of the new ejectors have not been made available at this time, ejectors are known to exploit the Venturi effect, using a primary fluid flow – typically the high pressure gas cooler outlet – which is then accelerated to draw in, mix and carry a secondary fluid at lower pressure to the suction side or liquid receiver. The use of ejectors reduces the compression ratio and the flow-rate handled by the compressor.

Although based on complex physical principles, integrated and intuitive controllers used to automatically configure the new modulating ejectors are said to make them simple to install and easy to use.

Carel has contributed to this project with the design experience acquired in the development of its own range of continuous-modulation electronic valves and high-efficiency control solutions. Carrier’s experience in transcritical CO2 refrigeration systems brought a significant reduction in fluid-dynamic design times.

“The cooperation between Carel and Carrier represents an example of synergy in which different competencies combine to bring to market technologically innovative solutions”, stated Francesco Nalini, Carel group managing director. “Through this cooperation we have made a tangible contribution to extending the use of natural refrigerants, in line with our guiding strategy: innovate to generate energy savings and reduce environmental impact.”