Small-scale vapour-compression systems play a key role in modern life, being extensively employed for satisfying many fundamental human needs (e.g. food preservation, medicine storage, water heating, cooling/heating of living spaces). The term small-scale refers to units whose required refrigeration/cooling and/or heating duties range between 2 kW and 20 kW (e.g. condensing units).
The energy and environmental policy implemented by the European Union is pushing small-scale vapour-compression systems to take a new and sustainable growth path. However, although immediate action is mandatory, such a large and ever-growing industry suffers for the lack of appropriate future-proof (i.e. eco-friendly, safe and high efficient) solutions. The overall aim of ECO2-RAPJECT is to bridge this technological gap by experimentally and numerically investigating a novel vapour-compression unit, offering:
- negligible direct contribution to global warming thanks to the use of CO2 as the only refrigerant;
- great energy efficiencies with the aid of a two-phase ejector featuring an innovative capacity control technique.
The new capacity control methodology is the focal point in the research/innovation project and based on pulse-width modulation (PWM) of the refrigerant flow through the ejector. Currently, two-phase ejectors cannot readily be capacity controlled without sacrificing ejector and system efficiency in small-scale vapour-compression systems.
Therefore, the specific objectives of ECO2-RAPJECT are to:
- establish the experimental evidence and expertise regarding a novel capacity control methodology for two-phase ejectors;
- numerically optimize the ejector and involved system sizing for improved ejector and system efficiency.
The project involves Danfoss A/S as a research partner.