Rapid pulse width modulated CO2 ejector for small-scale vapour-compression systems

Project Information

ECO2-RAPJECT

Grant agreement ID: 844924

DOI

10.3030/844924

Project closed

EC signature date 29 April 2019

Start date 5 August 2019

End date 4 August 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 207 312,00

EU contribution

€ 207 312,00

Coordinated by

DANMARKS TEKNISKE UNIVERSITET
Denmark

Periodic Reporting for period 1 - ECO2-RAPJECT (Rapid pulse width modulated CO2 ejector for small-scale vapour-compression systems)

Reporting period: 2019-08-05 to 2021-08-04

Summary of the context and overall objectives of the project

Small-scale cooling and heating systems are widely used in several vital applications, such as food preservation, medicine storage, cooling and heating of living spaces. However, this industry features both a significant direct contribution to global warming due to the massive use of environmentally deleterious refrigerants and a considerable indirect global warming impact owing to its substantial energy voracious.
The overall goal of ECO2-RAPJECT was to experimentally and numerically study an innovative small-scale system, offering:
(1) negligible direct contribution to global warming thanks to the use of CO2 as the only refrigerant;
(2) great energy efficiencies thanks to the implementation of a two-phase ejector featuring a novel flow modulation technique.
Establishing the experimental evidence and expertise regarding the new capacity control methodology, being based on the pulse-width modulation (PWM) of the refrigerant flow through the ejector, was the focal point of the project. No simple and cost-effective flow modulation mechanisms, in fact, were available for two-phase ejectors installed in small-scale cooling and heating systems. It was found that the PWM ejector offers energy savings above 10 %, thus offering much higher energy efficiency enhancements than today’s competitors. Having no practical size or application constraints, the suggested capacity control mechanism can lead to lay robust foundations for a significantly more sustainable future in the whole cooling and heating sector.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The work performed during the project included:
• project plan, coordination and management;
• development of a data management plan;
• establishment of the experimental evidence and expertise regarding the PWM capacity control methodology;
• experimental evaluation of the appropriateness of the installed ejector suction nozzle solenoid valve;
• upgrading and testing of the experimental apparatus;
• implementation of a comprehensive experimental campaign to investigate the effect of the frequency of the PWM on the performance of both the ejector and the overall system;
• conduction of an extensive experimental campaign to study the influence of the muffler presence and size on the performance of both the PWM ejector and the overall system;
• implementation of an exhaustive experimental campaign of a small-scale CO2 system equipped with the PWM ejector for refrigeration, air conditioning and heating purposes;
• conduction of a thorough experimental campaign of a small-scale basic CO2 system (i.e. without ejector) for refrigeration, air conditioning and heating purposes (as the benchmark);
• proof of the possible combination of the PWM ejector with an overfed evaporator to promote further energy savings;
• proof of the possible replacement of the PWM ejector with the PWM ejector motive nozzle in subcritical operating conditions;
• training in experimental campaign implementation, experimental Thermodynamics and data interpretation;
• Master courses in Experimental fluid dynamics and Computational Fluid Dynamics;
• attendance of introductory courses on Danish language and Data Management Plan implementation;
• supervision of a Master student and an Erasmus intern;
• establishment of new academic research collaborations;
• presentation of project results at international conferences and internal events;
• preparation and submission of journal articles for dissemination activities;
• outreach activities through participation in European Researcher night and Marie Curie Alumni Association.
The results of the project included:
• the proof of the novel flow modulation technique effectiveness and its greater potential compared to its today’s competitors;
• development of a wide and unique expertise about a very promising solution;
• unnecessariness of muffler adoption;
• availability of the experimental measurements collected from the test rig.
The outcomes were disseminated in 2 conference publications (i.e. 6th International Conference on Contemporary Problems of Thermal Engineering and 14th IIR-Gustav Lorentzen Conference on Natural Refrigerants), 1 international conference (i.e. ATMO/DTI Technical Conference on the Future of Air Conditioning) and 2 journal publications. Also, the results of the project will also be presented at the 1st Electric Vehicle CO2 Heat Pump Workshop as well as at the 7th International Symposium on Advances in Refrigeration and Heat Pump Technology after the end of the project (i.e. 30 August and 4 October, respectively). Furthermore, 3 scientific articles and 2 contributions to two international conferences in 2022 will be submitted in the next few months. The project activities were also disseminated via LinkedIn, ResearchGate, Twitter, Zenodo, fellow’s personal website and the project website. All these dissemination activities allowed reaching stakeholders (from both industry and academia) and favouring the outcomes towards industry. The outcomes of the results were transferred to the industrial partner by implementing two annual reports as well as by technical and status meetings. The outcome of the projects will contribute to fill the technological gap represented by the lack of a future-proof solution for small-scale cooling and heating applications. Therefore, a further step towards the achievement of the Sustainable Development Goals will be taken and the foundations for considerable enhancements for business and society concerning cooling and heating industry will be laid.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The progress of the project beyond the state of the art was:
• the cost-effective use of two-phase ejectors was successfully extended to small-scale refrigeration, air conditioning and heating applications;
• the groundwork for a future-proof solution for small-scale refrigeration, air conditioning and heating applications was done.
The project will pave the way for the commercialization of the next generation of small-scale cooling and heating systems, thus contributing to value creation and increased competitiveness for the industrial sector industry. Furthermore, developing expert knowledge in this field will help to stimulate investment and creating new jobs and businesses within the cooling and heating industry. The project also contributes to the development of cost-effective and sustainable cooling and heating solutions, decreasing the dependence on fossil fuels as well as the greenhouse gas emissions, thus helping to accomplish socio-economic and environmental targets in the context of the fight against the global warming.

Project diagram