Flawless operation of GEA BluAstrum provides non-freezing refrigeration for dennree warehouse

dennree, a wholesaler of organic foods and beverages, with home offices in Bavaria, Germany, installed an ammonia refrigeration system (6°C) and another using propane (2°C) in a conversion and expansion project. In the machine building three GEA Grasso BluAstrum chillers, operating with NH₃, provide refrigeration duty to new warehouse complex.

Located in Töpen, the dennree central warehouse accepts delivery of fresh product six days a week. Since April of 2014, an ammonia refrigeration system has cooled three of the bays in the four-bay complex, which has a total floor space of 25,000 m². Since their installation the ammonia chillers have provided flawless service, even during high-summer outdoor temperatures of over 30°C.

Total revamp of logistics building

Converted from a former central discount warehouse, the new dennree refrigerated warehouse complex stores around 2,000 open and packaged milk products and 550 various types of fruit and vegetables. Storage at different temperatures is provided in separate areas: apples at 4°C, tomatoes and cucumbers at 10 to 12°C, bananas at 14.5°C, and potatoes and root vegetables in the dark at 7°C.

The entire conversion and new installation of the refrigeration systems lasted approximately nine months, and required:

Complete stripping of the old logistics facility, including its floor and previous multicompressor refrigeration system
Insulating the building shell, constructing a new machine building, and installing an extensive piping system (approximately 3,500m long) for the brine
Installing a suspended ceiling to create an intermediate level that supports human traffic, accommodates the supply piping for the brine coolers, and provides space for the fire-protection system

GEA Grasso BluAstrum chillers provide 2400kW of cooling duty

The warehouse refrigeration is provided by a Hycool brine circuit, which is cooled by the ammonia evaporators of three ammonia GEA Grasso BluAstrum chillers. The three GEA Grasso BluAstrums, housed in a machine building, are automatically switched, alternatively, in accordance with cooling demand. During the winter, in low-load periods, one unit is sufficient to provide the required cooling duty. During hot summer periods, the entire installed capacity is required.

The energy efficiency ratio (EER) of the compressors at the desired evaporation temperature of -6°C is approximately 4.8. This high EER can be attributed to the physical properties of ammonia and to the effective speed control provided by the frequency inverters of the screw compressors.

GEA Grasso BluAstrum chiller are available in six model sizes and have a refrigerant charge of less than 90kg per kW of cooling capacity. The smallest refrigeration system is the GEA Grasso BluAstrum 500 with a maximum rating of 550 kW. The largest unit in this range is the GEA Grasso BluAstrum 1800, which has a maximum rating of 1,730 kW (cooling water from 12 to 6°C).

Brine network compensates for fluctuations in demand on cooling capacity

The brine network, which serves as a thermal “storage tank” and as a result eliminates the need for frequent start/stop cycles of the compressors, has six 30kW brine pumps that create a constant pressure drop between the supply and return lines. The volume of the brine circuit is designed to enable compensation, even for major fluctuations in demand on cooling capacity.

The initial pressure of Hycool brine is approx. 2.5 bar and the supply temperature of the brine is -3°C and the return, +2°C.

About GEA Refrigeration

GEA Refrigeration Technologies, part of the global GEA Group, is an expert in developing industrial cooling solutions. GEA’s solutions are present in the food and beverage sector; in the petrochemical, chemical, and pharmaceutical industries; on fishing ships; in natural gas liquefaction; in infrastructure facilities; and in ice factories. GEA Refrigeration prioritises value and functionality throughout the life cycle of its products.