All about the natural refrigerant ammonia (NH3) in cooling & refrigeration: News, Products, Jobs, Events, Knowledge, Forum, B2B Networking.

The Royal Fruitmasters Group, one of Holland's leading fruit suppliers, is converting its large cooling facilities from R-22 to ammonia refrigeration systems. The first phase of this conversion project started in April this year and is supposed to be accomplished this August. ammonia21.com asked Fruitmasters for some details on their ambitious project.

Due to ever stricter standards in food safety and transport temperatures for fruit, Fruitmasters must invest heavily in climate controlled premises. A closed chain system keeps the fruit at a constant temperature, from delivery right through to loading into the lorry.

Early experiments

In 2004, Fruitmasters in Geldermalsen commissioned 6000 m² floor surface area, 2900 m² of which being climate controlled. This came in addition to a number of cold stores for hard and soft fruit, occupying an area of 31.000 m².

At the time, Fruitmasters chose an indirect cooling system based on ammonia with a secondary system using Temper, a variant offering protection against freezing to -20°C. One of the main reasons for choosing an indirect system for storage of fruit was the possibility of achieving minor temperature differences between the cooler and the store air. This increases the relative humidity in the cold stores, so that the products are less likely to dry out.  

Complete conversion

Up to now, Fruitmasters has been mainly using the Freon refrigerant R-22, which is an ozone depleting substance. Under the Montreal Protocol this substance is being phased-out and from 2015 on there will therefore be no possibility to refill the systems.

For this reason, Fruitmasters has undertaken now, with the experience gained in ammonia refrigeration over the last years, the complete conversion from R-22 to ammonia. The first phase conversion project started in May and is supposed to be accomplished in August 2010. In the years 2011-2014 every year a part of the cold stores will be changed in the same way.

The Royal Fruitmasters Group has a cooling capacity of over 50 million kilograms of which 40% meet the Dutch STEK certification requirements. The STEK scheme is issued by the Dutch Refrigeration and Emission Prevention Foundation and aims at reducing leakages. It is actually stricter than the European f-gas regulation.

Until August, R-22 will be replaced by ammonia in 36 cool storage rooms. The recovered Freon will then be recycled in the refrigeration system of Coldstore Ochten and Citronas Rotterdam that still runs on R-22. In the conversion project, 32 cooling cells with 3,600 tons storage capacity will be converted by the company Kempen Koudetechniek. The adapted cells are centrally cooled by ammonia with a direct pumping system with much attention to energy consumption.

The major advantage of ammonia its high efficiency which in times of rising energy prices is an important criteria.

New coolers will furthermore be installed directly in the cells, making it possible to use even smaller temperature differences to work. This in turn will facilitate the use of Dynamic Control System (DCS)¹ for the storage of fruits in the cells and improve the quality of the product storage.  


¹ Dynamic control system (DCS) is an interactive, patented storage concept, which can be regarded as the successor of traditional controlled atmosphere (CA) storage for some commodities. Instead of using static, fixed set-points for gas conditions like in CA, the oxygen concentration in the DCS storage facility is controlled upon product response. When applying DCS, the oxygen concentration is slowly lowered until the product emits a stress-signal.