‘Go green’ with natural refrigerants

0
Bild: GettyImages/jeffbergen

A system concept befitting the philosophy of the company

Weiling GmbH, an organic fruit and vegetable wholesaler, has expanded its headquarters in Coesfeld by 12,500 m² to 23,300 m² of storage space. The new high-bay warehouse is cooled, the previous system was unable to deliver the extra cooling capacity and the previous R134a and R404A systems were to be replaced by a more efficient, modern solution, so a completely new refrigeration system was planned and built for the entire property.

Weiling GmbH was established in 1975 as an organic wholesaler and has grown from a pioneer in organic produce to a company with 600 employees. The company has its headquarters in Coesfeld and opened a new facility in Lonsee in 2010. Weiling supplies the finest organic produce from a range of more than 12,000 articles to over 1,000 independent organic food stores and supermarkets. From fresh and crispy organic fruit and vegetables, the finest organic cheese and dairy produce to a wide range of organic wines. Weiling has made it its mission to contribute to a fair, environmentally friendly world.

Staying true to its philosophy, the company opted for a solution with the natural refrigerants ammonia (R717) and carbon dioxide (R744). An ecological solution with an HTX-1 licence for use in areas with incidental food contact and consisting of renewable raw materials, all of which are 100 per cent biodegradable, was also chosen for the mixture of heat transfer fluids.

The contract for this new project was awarded to Kälte-Klima-Peters and its upstream supplier Robert Schiessl GmbH. Both companies had already been engaged to install the refrigeration system in Lonsee.

The refrigeration plant in Coesfeld now consists of an R717 liquid coolant system with three OSKA7452-K screw compressors from BITZER which delivers a cooling capacity of 555 kW when t0 = –9°C and Tc = 32°C. This system supplies the liquid coolant network (–7/–2°C). A second R717 liquid coolant system with four OSKA7472 screw compressors from BITZER has a capacity of 1,290 kW when t0 = –2°C and Tc = 32°C. This keeps the liquid coolant network (0/4°C) cool. For low temperature applications, the company uses two identical R744 compound systems each with three 4FSL-7K-40S compressors from BITZER. Each compound system has a cooling capacity of 86 kW when t0 = –31°C and Tc = –3°C. The systems always run in the sub-critical range and condensation is realised by the liquid coolant from the R717 systems.

The two liquid coolant networks supply all cooled areas and cold stores except the two low temperature storage facilities. In total, an area of 10,500 m² is cooled. This does not include the high-bay warehouse with its floor space of approx. 1,100 m² and height of 34 m. Inside, the warehouse has a set point range of 10–21°C. Therefore, depending on the temperature outside, the warehouse is heated if the temperature falls to 10°C and cooled if the temperature reaches 21°C.

The low temperature storage facilities have a combined area of approximately 1,300 m². Two R744 systems with direct expansion ensure the low temperature application. Each unit operates 50 per cent of the evaporators in the two cold stores. If one system should fail, the second system serves as a redundancy measure.

All of the systems are fitted with heat exchangers to recover heat. The waste heat is either used to heat the building directly through an intermediate circuit or fed into the 750,000-litre quenching water tank that serves as a storage tank. The temperature in the storage tank therefore ranges between 28 and 40°C.

The heat is only discharged through three air-cooled V-shape condensers from Thermofin when little or no building heating is required and the storage tank has been filled. As a result, no additional fossil fuels now have to be used to heat the building.

The entire system is controlled and regulated by a fully networked Siemens SPS control system. The control system regulates and visualises the entire refrigeration system with all connected cooling positions as well as heat recovery and building heating. All of the features and data of the entire system can be displayed and modified in clear displays using the touch panel or over the Internet. This type of system management is absolutely necessary for a project of this scale; it gives operators and service technicians a clear overview of the entire system and enables them to access it quickly.

System data:

COOLED AREA
Approx. 10,500 m2
Used for medium temperature applications and air-conditioning

Approx. 1,300 m2
Low temperature application

lus the high-bay warehouse
with an area of 1,100 m2
and height of 34 m (air-conditioning)

REFRIGERATION
LIQUID COOLANT SYSTEM 1
Three BITZER OSKA7452-K screw compressors
Cooling capacity: 555 kW when t0 = –9°C and Tc = 32°C
Refrigerant: R717
Coolant: Coracon WT EKO F-14, network –7/–2°C

LIQUID COOLANT SYSTEM 2
Four BITZER OSKA7472 screw compressors
Cooling capacity: 1,290 kW when t0 = –2°C and Tc = 32°C
Refrigerant: R717
Coolant: Coracon WT EKO F-14, network 0/4°C

COMPOUND SYSTEMS FOR LOW TEMPERATURE APPLICATIONS
Two identical systems, each with three semi-hermetic 4FSL-7K-40S
reciprocating compressors from BITZER
Cooling capacity: 86 kW when t0 = –31°C and Tc = –3°C
Refrigerant: R744

CONDENSER/OIL COOLER
Thermofin

AIR COOLER
For coolants and direct expansion
Thermofin

SYSTEM PLANNING AND CREATION:
Kälte-Klima-Peters in Meerbusch
Robert Schiessl GmbH in Oberhaching