Performance Study of Direct Integration of PCM into an Innovative Evaporator of a Simple Vapour Compression System

A new paper presenting HYBUILD outcomes has just been released by the GREiA Research Group, of the Universitat de Lleida in the Applied Sciences journal.

This paper experimentally investigates the direct integration of 3.15 kg of phase change materials (PCM) into a standard vapour compression system of variable cooling capacity, through an innovative lab-scale refrigerant-PCM-water heat exchanger (RPW-HEX), replacing the conventional evaporator. Its performance was studied in three operating modes: charging, discharging, and direct heat transfer between the three fluids. In the charging mode, a maximum energy of 300 kJ can be stored in the PCM for the cooling capacity at 30% of the maximum value. By doubling the cooling power, the duration of charging is reduced by 50%, while the energy stored is only reduced by 13%. In the discharging mode, the process duration is reduced from 25 min to 9 min by increasing the heat transfer fluid (HTF) flow rate from 50 L·h−1 to 150 L·h−1. In the direct heat transfer mode, the energy stored in the PCM depends on both the cooling power and the HTF flow rate, and can vary from 220 kJ for a cooling power at 30% and HTF flow rate of 50 L·h−1 to 4 kJ for a compressor power at 15% and a HTF flow rate of 150 L·h−1. The novel heat exchanger is a feasible solution to implement latent energy storage in vapour compression systems resulting to a compact and less complex system.

Read the full paper at

European Energy Efficiency Conference 2021

The European Energy Efficiency Conference 2021 shows how we can make a green recovery happen in practice and how energy efficiency is a cornerstone of this deep transformation.

What is it all about?

Europe has the ambitious goal of becoming the first climate neutral continent by 2050. The Green Deal and the EU Climate Law are first concrete steps. The current economic challenges are also an opportunity to accelerate decarbonisation and to create a fairer society and a more competitive economy.

In 2021, the conference – which attracts over 400 participants from over 50 countries each year – shows how we can make a green recovery happen in practice and how energy efficiency as an investment engine can contribute to this deep transformation.

HYBUILD is preparing a workshop at the 2021 European Energy Efficiency Conference in which the first results from its pilot sites, which are demonstrating the impact of the overall hybrid storage system, will be presented.

Read more about the event at

An innovative approach to Thermal Energy Storage and Self-Sufficiency in Buildings

The use of Thermal Energy Storage (TES) in buildings in combination with space heating, domestic hot water and space cooling has recently received much attention. End of 2019, the CHESS-SETUP H2020 project organised a webinar in which HYBUILD participated together with two other research projects RELaTED and SunHorizon.

The presentation from the Webinar is accessible at the following link :

Evaluation of the State of Charge of a Solid/Liquid Phase Change Material in a Thermal Energy Storage Tank

A new scientific paper published by the GREiA Research Group (Universitat de Lleida) and the Center for Energy of AIT (Austrian Institute of Technology) has been released on the Energies journal.

Monitoring of the state of charge of the thermal energy storage component in solar thermal systems for space heating and/or cooling in residential buildings is a key element from the overall system control strategy point of view. According to the literature, there is not a unique method for determining the state of charge of a thermal energy storage system that could generally be applied in any system. This contribution firstly provides a classification of the state-of-the-art of available techniques for the determination of the state of charge, and secondly, it presents an experimental analysis of different methods based on established sensor technologies, namely temperature, mass flow rates, and pressure measurements, tested using a lab-scale heat exchanger filled with a commercial phase change material for cooling applications.

Schematic view of the experimental set-up

The results indicate that, depending on the expected accuracy and available instrumentation, each of the methods studied here can be used in the present application, the deviations between the methods generally being below 20%. This study concludes that a proper combination of two or more of these methods would be the ideal strategy to obtain a more reliable and accurate estimation of the state of charge of the latent heat thermal energy storage. 

Read the full paper at :

Selection of the Appropriate Phase Change Material for Two Innovative Compact Energy Storage Systems in Residential Buildings

New research results from the HYBUILD project have been published by University of LleidaGREiA Research Group – in the Applied Sciences journal .

The implementation of thermal energy storage systems using phase change materials to support the integration of renewable energies is a key element that allows reducing the energy consumption in buildings by increasing self-consumption and system efficiency. The selection of the most suitable phase change material is an important part of the successful implementation of the thermal energy storage system. The aim of this paper is to present the methodology used to assess the suitability of potential phase change materials to be used in two innovative energy storage systems, one of them being mainly intended to provide cooling, while the other provides heating and domestic hot water to residential buildings. The selection methodology relies on a qualitative decision matrix, which uses some common features of phase change materials to assign an overall score to each material that should allow comparing the different options. Experimental characterization of the best candidates was also performed to help in making a final decision. The results indicate some of the most suitable candidates for both systems, with RT4 being the most promising commercial phase change material for the system designed to provide cooling, while for the system designed to provide heating and domestic hot water, the most promising candidate is RT64HC, another commercial product.

Read the full article at :

Keywordsthermal energy storage (TES)phase change material (PCM)heating and coolingmaterial selectionselection methodology

HYBUILD in a webinar on European funding for research and innovation

HYBUILD partner R2M Solution is organising a series of online webinars called ‘R2M Online Academy’.

On Tuesday 5th May 2020, HYBUILD was presented within a session focused on how to get involved in Horizon 2020 European collaborative research and innovation projects. The presentation detailed available funding and their mechanisms.

R2M Solution presenting HYBUILD in a webinar on European R&I

This webinar was organised in Italian but it might be replicated in English and other languages in the upcoming weeks.

The webinar has been recorded and is available to watch here.

Experimental study of a fin-and-tube heat exchanger working as evaporator in subatmospheric conditions

CNR-ITAE, Valeria Palomba & Andrea Frazzica have just released a new scientific paper which presents research results from HYBUILD published in Applied Thermal Engineering Journal.

The paper shows the potentialities of the latest addition to CNR ITAE’s self-developed lab systems: a testing bench for studying evaporation under vacuum in relevant scale heat exchangers for heat pump and refrigeration.

The paper is accessible here

Renewable Heating and Cooling Solutions for Buildings and Industry

Renewable energy technologies for heating and cooling are safe, clean, efficient and increasingly cost-competitive. In its vision 2050 prospective document, the European Technology and Innovation Platform on Renewable Heating and Cooling – RHC ETIP – envisions that 100% renewable energy-based heating and cooling (100% RHC) in Europe is possible by 2050.

This workshop will bring together a selection of H2020 EU-funded projects involving experts from the biomass, geothermal, solar thermal and heat pump sectors to discuss a common strategy for increasing the use of renewable energy technologies for heating and cooling for buildings and industry.

This workshop will be open to all external stakeholders registered to Sustainable Places 2020, Aix-les-Bains, France, 3-5 June 2020.

Participating projects :HYBUILD – SWS-Heating – CREATE – TRI-HP – HYCOOL – SHIP2FAIR – SUNHORIZON – Heat4Cool – GEOFIT – Innova microSolar – SolBioRevSCORES

Chair of the workshopAndrea Frazzica (CNR ITAE)

Further information about and registration at Sustainable Places 2020 at

Graeducation /Greening Seminar, Digitization and Entrepreneurship: Empowering Greek Vocational Education

Both the German and Greek vocational education systems face the challenge of adapting the necessary skills to modern labor markets. Climate protection is one of the aspects that leads to new skills requirements, especially in the technical professions.

Modern employment biographies require personal skills, which can be described as “business skills”. Digitization is seen as an issue, which is causing changes in many technologies and modifying to a certain extent the teaching and learning processes, in such a way as to require both teachers and students digital skills and a different view of their roles, teacher and trainee.

As part of the GRÆDUCATION project, a seminar idea was developed that takes into account these new requirements and was tested in Athens in the first week of December 2019.

The seminar included “green” business modules as well as interactive skills modules in the areas of employability and entrepreneurship.

The new skills acquired through the seminar will have to be incorporated into various Greek educational programs, and their implementation will be evaluated by the Greek-German project team.

Through the National Technical University of Athens, the HYBUILD project participated to the greening seminar. Key received feedback relates to:

  • incorporation into various Greek educational programs
  • Empowering Greek Vocational Education
  • leading to new skills requirements, especially in the technical professions

Further details about the event, get in touch with Dr. Vasiliki Tsiouri (Laboratory of Steam Boilers and Thermal Plants, School of Mechanical Engineering, National Technical University of Athens)

Applied Sciences special issue on “Design and System Integration of Thermal Energy Storage”

The worldwide commitment towards cleaner development by scaling down hazardous carbon emissions to avoid dangerous climate change calls for solutions that allow for the exploitation of renewable energy sources, and waste heat streams, reducing the energy consumption of systems in residential and industrial sectors. On the other hand, increasing human thermal comfort in micro and macro environments is of critical importance and requires innovative and advanced technologies.

One of the enabling technologies in this view is thermal energy storage (TES), which represents an essential component in a system architecture devoted to the maximisation of the share of renewables and energy efficiency. The intense research devoted to TES has led to the commercialization of different solutions, as well as the advancement of several TES systems for the most various applications from lab-scale towards full-scale real applications.

Our HYBUILD partner CNR ITAEValeria Palomba – is acting as Guest Editor, together with Dr. Mohammad Saffari from University College Dublin, for a Special Issue of MDPI journal Applied Sciences on the topic of “Design and System Integration of Thermal Energy Storage“.

Deadline for contributions is 31 October 2020 and further details are available through this link.