Project Results
Demonstration and integration
1. ZBK building demo site in cracow, Poland
1-1. introduction
Demonstration installation of the RESHeat project will be made for the building located at ul. Działkowa in Cracow, Poland.
It is a relatively new estate of 4 residential buildings in June 2013. All buildings have central heating installations and hot water powered by gas boiler houses. There is a separate boiler room for each building.
The heating demand of the demo site building is 108.1 MWh/year. The building is a multi-family building with 24 apartments, with a total usable area of over 1,190 m2.
There is a good chance of comparing the project results as three almost identical buildings built simultaneously with the same technology next to the selected building.
ZBK building demo site in cracow, poland
1-2. main components of the rESHeat system
- 68 stationary PV modules with a power output of 29.92 kW peak;
- 8 sun-tracking parabolic trough solar collectors;
- 2 sun-tracking photovoltaic/thermal (PV/T) systems, each consisting of 12 PV modules and a cooling system at their rear side;
- RE 76 heat pump with a maximum heating capacity of 95 kW;
- 2 buffer tanks with capacities of 500 L and 750 L with 2 immersed heat exchangers. The 750 L with immersed heat exchanger buffer tank is used as a domestic hot water tank supplier, and the 500 L buffer tank without heat exchanger is used for central heating;
- 1 insulated underground heat storage tank with a capacity of 50 m3 and immersed heat exchanger; 15 vertical ground heat exchangers, each 100 m deep;
- 4 heat exchangers.
The concept design of the RESHeat system for the ZBK demo site
1-3. Stationary PV modules
In the ZBK demo site, 68 PV modules, each with a peak power output of 440 W, are installed on the roof of the building. The maximum power output of the PV system is 29.92 kW.
Firstly, the roof of the building was prepared by installing the racks for the PV modules. After the installation of the rack system, PV modules are installed on the roof of the building, and the electrical connections are completed.
Once the connections on the roof are completed, the connection of the output of the PV system to the inverter is arranged. The cables are connected through the side of the building as the electrical box for the building was located in that section.
A 30 kW inverter was chosen to connect the output of the PV system. A similar approach is followed as in the Limanowa demo site. The generated electricity is consumed by the RESHeat system components, and the excess electricity is sold to the grid.
The pV rack, completed stationary PV system and inverter For The ZBK Demo Site
1-4. Sun-Tracking Sun Collectors
The sun-tracking parabolic trough collectors are used to generate thermal energy to cover the domestic hot water demand in the ZBK demo site building.
8 sun-tracking solar collectors are used to generate thermal energy with a peak of 30.4 kW. A water/glycol (35 %) mixture is used as the working fluid. The heat from the solar collectors is fed into a 750 L buffer tank.
The bottom side inlet of the 750 L buffer tanks is connected to the cold water supply, and the top side is connected to the existing domestic hot water tank.
Another heat exchanger is placed between the 750 L tank and the existing domestic hot water tank. The hot side of the heat exchanger is connected to the load side of the heat pump. The cold of the heat exchanger is fed from the water from the 750 L buffer tank.
Another heat exchanger is placed between the insulated underground heat storage unit and the cold water supply.
8 sun-tracking solar collectors’ hydraulic and electrical connections are completed, and the solar collectors are now fully functional.
Installation Of Parabolic Trough SCs
The hydraulic connections of the sun-tracking sCs
1-5. Sun-Tracking PV/T Systems
The RESHeat system includes two PV/T systems for the ZBK demo site. The foundation of PV/T systems was done on both sides of the insulated underground heat storage unit.
Each sun-tracking system consists of 12 PV modules with a total peak power output of 3.72 kW. The system’s electrical output is connected to an 8 kW inverter to be used firstly for the electricity consumption of the RESHeat system components.
Water/glycol mixture (35 %) is used as the working fluid for cooling PV modules in PV/T systems. Each PV/T system owns a pump for circulating the working fluid in the cooling system.
The immersed heat exchanger inside the insulated underground heat storage tank is connected to PV/T systems. Therefore, the thermal energy generated within the PV/T systems is rejected to the water inside the underground heat storage unit.
The heat generated within the system supports the lower source of the heat pump to allow the operation of the heat pump with high COP.
The installed PV/T systems at the ZBK demo site
1-6. Heat Pump RE 76
The heat pump is used to generate thermal energy to cover the heating demand of the space heating and the domestic hot water when there is not enough thermal energy generation within the sun-tracking solar collectors.
A water-to-water heat pump RE 76 with a maximum heating capacity of 95 kW is installed at this demo site.
The heat pump consists of 2 evaporators and 2 condensers.
The ground heat exchangers are connected to the down-source side of the heat pump. The return of the source side of the heat pump is either circulated through the heat exchanger or circulated through the ground heat exchangers. The load side of the heat pump is connected to the central heating buffer tank for space heating and the hot side of the 95 kW heat exchanger.
The RE 76 heat pump in boiler room
1-7. Underground heat storage unit
An insulated underground heat storage unit, with a 50 m3 capacity and immersed heat exchanger, is used to store thermal energy for the source side of the heat pump.
The excavation area is surrounded by barricades in order to eliminate any risks, and only authorized persons are allowed to enter the area.
A crane is used to place the underground heat storage unit. The insulated underground heat storage unit is filled with water. The immersed heat exchanger is connected to the outlet of the PV/T system, and the water/glycol mixture is circulated.
The water inside the insulated underground heat storage unit is connected to three heat exchangers. The water is circulated through the hot side of one of the heat exchanger for delivering thermal energy to the lower source of the heat pump.
Another connection of the insulated underground heat storage unit is to the cold side of the other heat exchanger. The last connection of the tank is made to the hot side of the heat exchanger in order to reject heat to the cold domestic hot water supply.
The underground storage unit placement area
Placement of the insulated underground heat storage unit at the ZBK demo site
1-8. Vertical Ground Heat Exchangers
15 each 100 m deep vertical ground heat exchangers are installed at the ZBK demo site for dissipating the excess heat to the ground during non-heating seasons to utilize the thermal energy for the lower source heat pump during the heating seasons.
Once the boreholes are prepared, U-tube heat exchangers are placed. The hydraulic connections of the ground heat exchangers are completed at the demo site.
Piping of ground heat exchangers
The RESHeat system started to provide heating for the ZBK demo site building as the protocols were confirmed.
The SCADA system installed at the demo site is shown below.
The SCADA System at the ZBK demo site
2. TOP-CEZAR V building Demo Site in Limanowa, Poland
2-1. Introduction
The RESHeat system is being developed at Top-Cezar V, Limanowa demo site and is planned to cover the energy demand of the 1 storey of the building, which consists of a multi-family storey with 9 apartments.
The apartments occupy 433 m2 of the building. The heating system of the building is built with the insulated two-pipe pumped water system powered by 2 gas boilers, Dietrich 75 kW each.
Central heating radiators are used in apartments. The heating setpoint temperature is 22 °C, and the setback temperature is 20 °C. Due to the moderate climate in the region, cooling is not needed at the building.
The installation is a floor-standing system equipped with individual heat meters for each apartment. There is a chance to compare the results with the energy demand and coverage of the other storeys in the building.
TOP-CEZAR building in Limanowa/Poland
2-2. Main Components Of The RESHeat System
- 46 stationary PV panels with a power output of 20.24 kW peak;
- 5 sun-tracking parabolic trough collectors with the thermal output of 19 kW peak;
- 2 sun-tracking photovoltaic/thermal (PV/T) systems, each consisting of 12 PV modules and a cooling system at their rear side;
- RE 33 heat pump with a maximum heating capacity of 42 kW;
- 5 U-tube vertical ground heat exchangers, each 100 m deep;
- 1 insultaed underground heat storage tank with a capacity of 50 m3 and immersed heat exchanger.
The concept installation of the RESHeat system for the TOP-CEZAR demo site
2-3. Stationary PV Modules
In the TOP-CEZAR, 46 PV modules, each with a power output of 440 W, are installed during the project documentation. The peak power output of the stationary PV system is 20.24 kW.
Firstly, the rack for the installation of the PV modules is prepared. While preparation of the rack, PV modules are installed simultaneously. The generated electricity is in the form of a direct current (DC) will be converted to an alternative current (AC) before connecting to the grid and the RESHeat system components.
A 20 kW inverter was chosen to connect the output of the PV system. The generated electricity is consumed by the RESHeat system components, and the excess electricity is sold to the grid.
Completed stationary PV system installation At The TOP-CEZAR Demo Site
2-4. Sun-Tracking Sun Collectors
The sun-tracking parabolic trough collectors are used to generate thermal energy to cover the domestic hot water demand mainly of the inhabitants in the TOP-CEZAR demo site building.
5 sun-tracking solar collectors are used to generate thermal energy with a peak of 19 kW. A water/glycol (35%) mixture is used as the working fluid. The outlet of the solar collectors is connected to a three-way valve.
The sun-tracking solar collectors’ hydraulic and electric connections are completed, and the solar collectors are now fully functional.
Installation of parabolic trough solar collectors At The TOP-CEZAR Demo Site
The hydraulic connections of the solar collectors At The TOP-CEZAR Demo Site
2-5. Sun-Tracking PV/T Systems
The RESHeat system includes 2 PV/T systems for the Limanowa demo site. The construction of the sun-tracking PV/T system starts with the arrangement of the foundation.
The sun-tracking PV/T systems consist of 12 PV modules and a cooling system at their rear side for harvesting the waste heat from modules. Each sun-tracking PV/T unit produces 5.18 MWh/y of thermal energy and 2.80 MWh/y of electrical energy annually.
Water/glycol mixture (35%) is used as the working fluid for cooling PV modules in PV/T systems. Each PV/T system owns a pump for circulating the working fluid in the cooling system. The outlet of each PV/T system is connected to the hot side of a heat exchanger. The cold side of the heat exchanger is connected to the manhole collector well.
The harvested heat is utilized for the lower source of the heat pump to maintain the coefficient of performance (COP) of the heat pump as high as possible.
The PV/T installation At The TOP-CEZAR Demo Site
The manhole collector well At The TOP-CEZAR Demo Site
The heat pump is used to generate thermal energy to cover the heating demand of the space heating and the domestic hot water when there is not enough thermal energy generation within the sun-tracking solar collectors.
A water-to-water heat pump RE 33 with a maximum heating capacity of 42 kW is installed at this demo site.
The heat pump consists of 2 buffer tanks with 1 immersed heat exchangers.
The load side of the heat pump is connected to the central heating buffer tank, which is filled with water. The central heating buffer tank contains an immersed heat exchanger, which is connected to the domestic hot water tank.