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Trigeneration systems based on heat pumps with natural refrigerants and multiple renewable sources.

Periodic Reporting for period 1 - TRI-HP (Trigeneration systems based on heat pumps with natural refrigerants and multiple renewable sources.)

Reporting period: 2019-03-01 to 2020-04-30

The overall goal of the TRI-HP project is the development and demonstration of flexible energy-efficient and affordable trigeneration systems. The systems will be based on electrically driven natural refrigerant heat pumps coupled with renewable electricity generators (PV), using cold (ice slurry), heat and electricity storages to provide heating, cooling and electricity to multi-family residential buildings with a self-consumed renewable share of 80%. TRI-HP systems will include advanced controls, managing electricity, heat and cold in a way that optimizes the performance of the system and increases its reliability via failure self-detection. The flexibility will be achieved by allowing for three heat sources: solar (with ice/water as storage medium), ground and ambient air.
The innovations proposed will reduce the system cost by at least 10-15% compared to current heat pump technologies with equivalent energetic performances. Two natural refrigerants with very low global warming potential, propane and carbon dioxide, will be used as working fluids for adapted system architectures that specifically target the different heating and cooling demands across Europe. The newly-developed systems will find application in both new and refurbished multi-family buildings, allowing to cover the major part of Europe’s building stock. The new systems reduce GHG emissions by 75% compared to gas boilers and air chillers.
The TRI-HP project will provide the most appropriate knowledge and technical solutions in order to cope with stakeholder’s needs, building demand characteristics, local regulations and social barriers. Two system concepts will be developed for two different combinations of heat sources, i) dual ground/air source and ii) solar with ice-slurry as intermediate storage. These two concepts combined with the two heat pump types developed (carbon dioxide and propane) will lead to three complete systems (CO2-ice, propane-ice and propane-dual) that will be tested in the laboratory.
"During the reported period, the technical work was grouped in six work packages (WP):

• WP 1: System requirements, simulations and boundary conditions (lead by TECNALIA)
Reference buildings and energy demands (heating, cooling, electricity and DHW) for typical multi-family buildings were developed. Results of this work are described in detail in the report D1.1 ""Energy demands for multi-family buildings in different climatic zones"" available on Zenodo with DOI:10.5281/zenodo.3763249. A system simulation framework has been further developed in python to build, run and process TRNSYS simulations. This python package has been made available in GitHub for the TRI-HP partners and it will be open to the general public during summer 2020.

• WP 2: Social acceptance and barriers (lead by ISOE)
Understanding and improving stakeholders’ acceptance of TRI-HP systems was made in the frame of WP 2. An in-depth literature review on the state of the art of new technologies and the acceptance of innovation as well as a gender analysis on renewable heating and cooling technologies was carried out.
The review on social acceptance and the gender analysis showed key social and contextual factors that could promote or impede further developing and upscaling of TRI-HP systems. Detailed results achieved within the reported period are reflected in ""D2.1 Social issues of novel RE heating and cooling systems"" available on Zenodo with DOI: 10.5281/zenodo.3763715.

• WP 3: Icephobic coatings and bulk materials (lead by DTI)
Reliable icephobic coatings and bulk materials to be applied on the supercooler to prevent ice blockage were investigated in WP 3. Smooth hydrophobic and amphiphilic coatings have been investigated. As there are no standardized procedures for assessing the performance and durability of icephobic coatings for underwater application, the focus was also on developing laboratory testing procedures for the selected icephobic coatings and bulk materials. We have tested 12 hydrophobic and three amphiphilic coatings. For comparison purposes we also tested reference surfaces, non hydrophobic sol-gel and commercial coatings. The selected coatings will be used to coat existing commercial heat exchangers. The bulk materials will be used to fabricate a new heat exchanger concept. The cost target for the coating is 20 €/m2 considering material and application on an industrial scale was reached for the selected coatings.

• WP 4: Heat exchangers (lead by UASKA)
WP 4 focuses on the heat exchangers that will be used in the heat pump systems from WP 5. In the first reporting period, two heat exchangers were designed and developed:
- a tri-partite gas cooler for a R744 heat pump
- a dual-source heat exchanger with a direct exchange between sources/sinks (air/earth) for the R290 heat pump.
The design, construction and testing of the supercoolers will be done within autumn 2020.

• WP 5: Heat pumps (lead by NTNU)
The modelling, design and manufacturing of the heat pump prototypes using natural refrigerants (carbon dioxide R744 and propane R290) has started within WP5. Three designs are currently available:
- R290 heat pump using a dual source/sink evaporator/condenser
- R290 heat pump using a supercooling ice slurry concept
- R744 heat pump using a supercooler ice slurry concept
The testing phase will start during summer 2020.

• WP 6: Advance controls for energy management and self-detection (lead by IREC)
The first steps for developing an efficiency drift self-diagnosis algorithms aiming at identifying performance issues of individual heat pump systems have been done. The design of one of components of the Advanced Energy Manager System (AEMS), called Central Controller was also made. The optimization is based on Model Predictive Control (MPC) which finds the optimal strategy in terms of electricity cost savings and energetic system performance.

The work performed during the period covered by the report is reflected in 20 deliverables. A number of 11 milestones were achieved during period. The main achivements and all public reports can be found on TRI-HP website (www.tri-hp.eu). Periodic news are posted also via TRI-HP social media profiles (Twitter, LinkedIn, ResearchGate). TRI-HP is active in EU platforms, such as the Build Up portal, REHVA website and other national platforms that are also used in the communication activities."
The TRI-HP project will lead to several results that go beyond the state of the art. Icephobic materials, improved heat exchangers and natural refrigerant heat pumps together with the advanced management system will be tested and integrated in a complete system. The first-of-a-kind system prototype for solar-ice systems targeting residential applications using the supercooling ice slurry method will be built and tested as a whole in the Concyse Cycle Test. Interests and needs of the end-users, installers and other relevant stakeholders as well as of the different geographical and cultural contexts are considered in the development of TRI-HP system.
In the first reporting period, a special focus was dedicated to icephobic materials including coatings and bulk materials to be used in immersed conditions with flow conditions. The selected icephobic coatings and the bulk material developed in TRI-HP are chemically stable and able to maintain icephobic properties underwater. Validation in with water flow conditions is currently in progress.