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Hybrid Variable Geometry Ejector Cooling and Heating System for Buildings Driven by Solar and Biomass Heat

Periodic Reporting for period 1 - Hybrid-BioVGE (Hybrid Variable Geometry Ejector Cooling and Heating System for Buildings Driven by Solar and Biomass Heat)

Reporting period: 2019-06-01 to 2020-11-30

The Hybrid – BioVGE project has the primary objective of developing and demonstrating a highly integrated solar/biomass hybrid air conditioning system for cooling and heating of residential and commercial buildings that is affordable, operating with improved efficiency and reduced need for maintenance. The project contributes to overcome the existing technological barriers of solar/biomass small-scale space heating and cooling systems, such as high system complexity, lack of demonstration plants and lack of experience to improve their performance.
The project focuses on the development of three highly integrated prototypes adequate for residential and small commercial buildings. The activities involve component design and integration, control system development and field-testing. The proposed system is composed by a solar collector field, biomass boiler, thermal energy storage unit using PCM, thermally driven variable geometry ejector chiller, heat distribution and intelligent integrated control system. A TRL of 7 is expected to be reached by the end of the project.
A significant amount of work is carried out to optimise the design individual components for the Hybrid – BioVGE system. Regarding solar collectors, the objective is to reduce the cost of heat generation. Biomass boiler design will be improved to increase fuel flexibility. Thermal energy storage will be optimised in terms of storage capacity, storage design and storage medium for the hybrid space heating/cooling system. Variable geometry ejector chiller will be developed with adequate control strategy and working fluid for residential and commercial buildings. Thus, another objective of the work is to develop a unified design software that will assist component selection and forecasting of the Hybrid – BioVGE system performance.
If successful, the project will lead to a solution that is capable of satisfying 95% of the thermal load of the selected buildings from renewable energy sources, with an electricity consumption less than 5%. It is also expected that the developed Hybrid – BioVGE system will operate with a solar heating fraction above 40% for central European climates and above 60% for southern European climates; and with a solar cooling fraction above 90%.
The project implementation plan is divided into 10 work packages (WPs), seven of which are of technical nature, as shown in Figure 1. The project was scheduled for a total duration of 36 months. The first half (18 months) was mostly dedicated to prototype development (WP2-WP5), a period of 6 months will be used for assembly of 1 unit and testing under relevant operating environment (CCT tests) , and the final (third) year will be used for installation and field-testing of the two remaining systems under operational conditions. Complementary activities (WP1, WP9 and WP10) are be distributed along the entire project duration.
WP1 is concerned with the coordination of the Project. Day-to-day coordination was carried out via email communications and phone calls. Four progress meetings were held, including kick-off, to discuss general progress. Two deliverables were submitted with the project management (D1.1) and data management plan (D1.2).
WP2 focused on the thermal load assessment of the selected buildings for prototype installations, a newly built family home near Porto and office rooms in Steyr (Solarfocus). The hourly heating and cooling loads were determined by applying dynamic numerical models. For this purpose, numerical building models were developed. Important results of WP2 were that the prototypes should be designed for cooling capacities of 5 kW and 10 kW for Porto and Steyr, respectively. The models predicted that solar fraction values will meet target values for heating and cooling during most Summer weeks. Two deliverables associated to WP2 were produced and submitted on time.
The effort in WP3 was dedicated to define the full technical details of the main system components (subsystems) for the three prototypes. This includes solar collector type, size and configuration (Figure 2); biomass boiler; PCM type, storage mass and VGE chiller (Figure 3). The work involved theoretical and experimental approaches. Design details for all components are now available for each prototype. Three deliverables were produced with the outcomes of WP3.
WP4, focusing on the prototype assembly and integration methods, was also concluded during the first reporting period. System configuration was optimised, hydraulic connections and building integration methods were defined for each test site. Initial preparation for prototype installation at the Porto test site was carried out during the construction phase of the building. Two deliverables (D4.1 and D4.2) were produced.
WP5 aims the development the energy monitoring and control unit for the Hybrid-BioVGE system to assure efficient, safe and long-term operation with little need for interference by the end user. This WP was foreseen to terminate in M19, however it will suffer some delay. The work plan needed to be restructured and reallocated to Solarfocus partner. Work tasks, such as the selection of the transducer types and sensors (WT5.2) and development master control unit and functional modules (WT5.3) are nearly completed (Figure 4). The remaining work tasks in this WP are still ongoing. It is expected to conclude WP5 in the first quarter of 2021.
The activities within WP9 focused on dissemination, communication and exploitation of the results of the project in order to maximise the impact of the Hybrid-BioVGE technology. The website of the project was set up in an early stage of the implementation. Several presentations were made in workshops and clustering events. Currently two scientific papers are under preparation to publish in open access journals.
The project implementation involves voluntary participation of humans during field-testing. In WP10, the ethics principles to be respected by all persons working in the project were laid out. Submitted deliverable D10.1 provides details on the principles and procedures that will be implemented by the Consortium for collection, storage, protection, retention and destruction of personal data.
A measurable socio-economic impact is expected, after project results, prototype demonstration and dissemination activities. Several technical developments were achieved at component level during this first reporting period, leading to high potential for new patent applications or license agreements. The outcomes of the concluded WPs are in-line with the initial expectations. Simulation results indicated that the Hybrid-BioVGE prototypes will deliver target solar fractions, while requiring only a small amount of electricity. Improved collector design allows for initial cost reduction and improved solar fractions. Improved boiler design clearly demonstrated technological advances regarding fuel flexibility and reduced emissions, when compared to state of the art technologies. Results also indicated that the developed variable geometry chiller performs considerably better than fixed geometry solutions. Cold storage using PCM will increase compactness of the prototypes and contribute to higher solar fractions during the cooling season. At system level, overall impact and progress with the developed Hybrid-BioVGE prototypes will be assessed based on the concise cycle test and field-testing activities during the second reporting period.
Project logo
Figure 3 - VGE chiller design
Figure 1 - Work package diagram
Figure 4 - Master controller and functional modules
Figure 2 - Solar collector size and layout Porto test site