In the world of fresh produce storage, cooling based on ammonia is a proven technique with very favourable energetic returns and good storage qualities for the product. “Until recently, the necessary investment in an ammonia pumping system was seen as an obstacle for smaller stored quantities of 100 to 500 tonnes. With the realisation of our NH3-DX installation, we have now proven that ammonia is also feasible for smaller projects and businesses economically,” says Robert Glerum, business manager of Glerum Koel-en Klimaattechniek in Goes, the Netherlands.
“The development of the installation was realised as part of an IPC project for which the possibilities for small cooling installations based on natural cooling were researched. The result is a properly working ammonia ‘direct expansion’ installation that is a true price buster compared to conventional ammonia pumps,” Robert says.
The first of these NH3 installations was built at the MTS de Koeijer farm in Brouwershaven. Owner Joop de Koeijer is specialised in growing seeds of chips potato varieties. The entire process of planting, growing, grubbing up, storage, sorting and packing happens at the company. Besides seeds, chicory roots are also cooled at this sustainable farm. After the harvest, these roots are stored in potato crates in two cells. This occurs in the period from November until March. After that, the roots are grown into chicory in cells. During the storage period, it’s important that the roots cool from about 1.0 ºC (in November) to about -1 ºC (in January). The chips potatoes are stored cold from March until August.
On the ladder of sustainability, the ammonia installation scores high. It’s a green coolant, and is considered energetically superior, so that the future seems secured. The installation can be presented in its entirety for the Energy-Investment deduction (the Dutch EIA), so that the government meets the purchase price of the installation.
Evaporator construction
The NH3-DX coolers are equipped with special inlet hoods and blow socks. The coolers are periodically thawed when cell temperatures are below two degrees; during thawing, these socks close, so that the ventilator side of the cooler is closed off. Because of this, the (rising) heat from the cooler flowing over into the cooled space is prevented.
In the cooler, the NH3-concentration is continuously measured. The expansion valve and other components are built in the cooler casing. When the alarm value is exceeded, coolant supply will be immediately stopped. Additionally, a valve channel is attached to the cooler, which automatically suctions out contaminating vapours. Compared to pumping systems, the NH3-DX coolers need a very limited filling, only three kilos per cooler.
Cooling aggregate
An outdoor installation of the cooling aggregate was chosen. Because of this, the installation can be delivered ‘ready-made,’ as it were, and installation time is limited. The added-on machine chamber isn’t inferior to the average machine chamber. The compressor space is completely isolated, both thermally and acoustically, and it’s equipped with heating in winter and ventilation in summer. According to PGS-13 guidelines, the space has also been equipped with NH3 detection and guided ventilation.
Operation
Near the cooling cell doors, there’s an operating panel, with which the set-up can be put in, and it also shows relevant temperatures. The installation has been taken up in the ‘internet of things’ and with the additionally supplied mobile application, the controls can be operated over a secure VPN connection on smartphones or tablets.
Practical experience
The installation was put into operation in the autumn of 2015. Both the cooling stage and the storage stage were to the satisfaction of both the installer and the final user. By now, the installation also stores seed potatoes, and this is also going very well. The second season for the chicory roots was recently successfully started completely independently by De Koeijer.