Chillers & heat pumps
Cold and Heat in One Circuit: Graewe and L&R Implement Combined System with Over 50% Energy Savings
Graewe's Finnentrop plant has commissioned a 570 kW R290 refrigeration system for thermal treatment, complemented by a 125 kW heat pump for underfloor heating. The system was designed and installed by L&R Kältetechnik in a containerized format; compared to a standard refrigeration unit, the energy savings potential exceeds 50%.
High-strength fastening component manufacturer Graewe GmbH & Co. KG has commissioned a combined system at its Finnentrop plant: a 570 kW refrigeration unit for thermal treatment and a 125 kW heat pump for underfloor heating. Compared to a standard refrigeration unit, the energy savings potential is significantly more than 50%. The equipment was designed, manufactured, and installed by L&R Kältetechnik.
Graewe specializes in the production of high-strength threaded studs and bolts to DIN 976-1 for industrial and construction applications. These components are used in wind energy, agricultural machinery, and motorway infrastructure, where stability, durability, and reliability are critical. Mechanical properties are achieved through thermal treatment that forms a fine-grained, homogeneous structure, requiring precise temperature control during heating and controlled cooling.
Refrigeration unit
The system delivers 20 °C water (return 26 °C) with a cooling capacity of 570 kW. Two refrigeration circuits provide redundancy, and the division into eight power stages enables high energy efficiency at part-load operation.
Key energy-efficiency features:
- Free cooling: at low and medium ambient temperatures, free coolers cover the cooling demand using the surrounding environment, saving up to 86 kW of electrical energy at full load.
- Two outdoor condensers of 345 kW each; free-cooler and condenser fans are driven by EC motors with frequency control.
- Pumps in the liquid circuits with variable-speed drives, efficiency class IE5.
- VariKon system: automatic adjustment of condensing temperature to ambient temperature via electronic expansion valves, minimizing the pressure differential. Savings of up to 38 kW.
Refrigerant
Propane R290 (GWP = 3, ODP = 0) was selected as the refrigerant — a natural, PFAS-free substance available worldwide. R290 allows the design of efficient refrigeration circuits in the 20 °C range. R290 equipment is eligible for BAFA subsidies. Safety is ensured by gas detection and automatic ATEX ventilation.
Heat pump for underfloor heating
The heat pump, also designed and built by L&R, uses 26 °C water from the "hot tank" of the cooling circuit and heats it to 40 °C for the underfloor heating system in the plant. The design is analogous to the refrigeration unit (evaporator, condenser, water and R290 circuit) but operates "in reverse." Thermal output is up to 125 kW at an electrical input of approximately 20 kW, yielding a COP of 6.2. Control is via a Siemens S7 PLC, with visualization on a touch panel.
Monitoring and safety
Production pumps are redundant: when one is under maintenance or fails, the backup automatically engages. The touch panel displays all operating parameters and error messages. A built-in electricity meter with correlation to delivered heat enables continuous calculation of efficiency and total energy consumption; data is transmitted to the plant's energy management system.
The refrigeration unit and heat pump are housed in a single process container. The container is delivered fully assembled with pipework — on site, only connection and commissioning are required.
Olaf Graewe, managing co-owner of Graewe GmbH & Co. KG, noted that thanks to the efficient refrigeration unit, the company saves not only money but also valuable resources, reducing its carbon footprint.
Source: www.lr-kaelte.de
ORIGINAL SOURCE
Die Kälte + Klimatechnik ↗Visit the original source for additional details.
