HYBUILD full hybrid storage integrated

A new report led by our partner AIT – the Austrian Institute of Technology – is now available on the Deliverables page of the website.

Executive Summary

The HYBUILD public report “Full hybrid storage integrated” describes the integration phase of the hybrid storages for the Mediterranean and the Continental concept in the laboratories. Special focus was put on the hydraulic and electric integration of the main components. With this report, the knowledge about the integration of the specific components of the HYBUILD concepts is passed to the demo sites inside the HYBUILD project, where the technologies will be installed. Furthermore, it may help researchers and developers working on future experiments with the same or similar components. Therefore, potential problems in the system integration can be identified in advance.

Although the thermal and electric storages used in both concepts of HYBUILD are similar, their integration into the two concepts is different. Hence, both concepts are always dealt separately in the following.

For the Mediterranean sub-system, the main purpose of the activity described in this report was the integration of the different components: heat pump with latent storage (RPW-HEX), batteries with DC bus and sorption module and the subsequent integration of all of them together at lab scale.

For the Continental sub-system, the main purposes were: the integration of the heat pump with a DC powered inverter and the latent storage (RPW-HEX) in a first experimental test series (2019) and the integration of the heat pump with a DC powered inverter, the latent storage (RPW-HEX), the decentralized DHW storages and the thermal controller in a second experimental test series (2020). The aim of the second test series was also to demonstrate heating/cooling and DHW-generation operation under realistic test conditions in the lab.


Mediterranean sub-system: At first, the integration of the heat pump and the latent storage was verified by carrying out operational tests at NTUA and CNR (Figure I) in different lab infrastructures. The integration of the DC bus with the batteries was tested at CNR by simulating through a custom software realistic operating conditions and subsequently by connecting the DC bus to the heat pump and the latent storage. The operation of the sorption module by itself integrated in the thermal lab of CNR was verified through tests in operating conditions. Subsequently, the full sub-system integration with a simplified layout was prepared, also considering all the sensors and devices needed for the lab-scale testing of the complete sub- system (to be reported in the upcoming deliverable D3.4).

Figure I: integration of the latent thermal storage in the heat pump – focus on refrigerant circuit. 1: condenser, 2: standard evaporator, 3: compressor, 4: liquid receiver, 5: expansion valve, 6: RPW-HEX

Continental sub-system: After testing the OCHSNER heat pump without latent storage (RPW- HEX), the first version of the Continental RPW-HEX manufactured by AKG was tested experimentally together with the OCHSNER heat pump at AIT’s thermal lab infrastructure under different operational conditions. With the knowledge gained from this first experimental test series, the RPW-HEX was redesigned by AKG and AIT, the heat pump was retrofitted by OCHSNER and a thermal controller, hydraulic modules and three decentralized DHW storages provided by PINK were further integrated in the adapted experimental setup at AIT (Figure II). Data from more than one hundred sensors were monitored and partly further processed to control the operation of the sub-system. For this purpose, it was necessary to build up a combined data acquisition (DAQ) and control system including the components from OCHSNER (HP controller and HP internal DAQ), PINK (thermal controller and DAQ of DHW storages and hydraulic modules) and AIT (general DAQ of all needed sensors for the experiment and master control).

Key findings and conclusions

Mediterranean sub-system: The integration of the different components was properly designed in order to make it as smooth as possible, considering the relevant number of components which need to be properly integrated from the hydraulic as well as electrical point of view. All the single components were commissioned, proving their proper operation and, once integrated, they will be tested to verify the full sub-system operation. No major issues in the integration phase were highlighted, which makes this phase easy to be performed also at the demo sites level.

Continental sub-system: The experience from the integration of the RPW-HEX in the HP cycle in the first experimental test series helped to improve the RPW-HEX integration in the HP cycle for the second experimental test series. In the second test series, all crucial components except the DC bus controller, which was tested at CNR, were already integrated in the lab and tested. In both experimental test series, many problems that occurred during the integration phase were solved in the lab at AIT and components and control strategies were constantly improved through prompt consultation with the industrial partners AKG, OCHSNER and PINK.

Figure II CONTINENTAL experimental set-up at AIT (2nd test series). 
(a) Outdoor unit (O) including evaporator, fan, expansion valves and sensors located in the outer climatic chamber.
(b) Panorama image of the set-up located in the inner climatic chamber at AIT. (1) hydraulic interface to lab infrastructure, (2) connecting pipes (return- and feed-line of external water cycle connected to (H), return- and feed-line to the heat-sink/source, fresh water and DHW water), (3) refrigerant connections to the outdoor unit located in the adjoining outer climatic chamber, (4) supporting frame for the RPW-HEX and the volume flow sensors, (H) hydraulic separator between HP internal water cycle and external water cycle, (HP) indoor unit of the heat pump, (Q) DC generator, (R1,R1) RPW-HEX modules, (T) Thermal controller, (X1)-(X3) enerboxxes, (Z) B&R DAQ and process control system connected to the thermal controller (T) and the HP controller.

Lessons learned

Mediterranean sub-system: Lessons learned for the installation in Mediterranean demo sites are related especially to the de-aeration of hydraulic circuits and the use of the proper mixture of water and glycol-anti-corrosion liquid. Indeed, due to the relevant number of plumbing components and separated circuits, the proper de-aeration components need to be installed to allow a quick and reliable filling of the whole circuit. Similarly, the proper mixture of water and anti-corrosive additive liquid needs to be prepared to fill in all the circuits in which aluminium heat exchangers are operated (i.e. both sorption module and latent RPW-HEX).

Continental sub-system: During the integration phase of the components, many problems were overcome, and several solutions were developed to improve the component and the overall system. Problems with accumulation of oil in the RPW-HEX, unwanted heat bridges and structural issues in the RPW-HEX were solved by redesigning of the RPW-HEX. The HP was retrofitted between the first and second experimental test series and will further be improved before it will be installed on the demo-site. Furthermore, problems with sensors, insulations, or communication interfaces were identified and possible solutions were reported.

Read the full report

The full report can be read here.