Refrigeration / Fruit & Vegetable Storages
PUR Organic Products
Sustainable. From production to delivery. How fresh organic vegetables get to the consumer months after being harvested depends on the storage conditions. Only when the temperature, CO2 level and humidity are spot on will the flavors and vitamins be preserved for longer periods, thus taking the pressure off the storage situation (e.g. due to sprouting). And that is why organic distributor PUR Organic Products makes no compromises when it comes to the cooling system for the warehouse in Oberweiden, operated by its subsidiary PURes Biogemüse GmbH, which was completed in 2019.
PUR Organic Products has invested over EUR 5 million to build one of the country's largest organic warehouses, comprising 2,000 m³ of concrete, 400 t of steel and 10,000 m² of insulation panels. The heating and cooling technology was planned and installed by ENGIE Kältetechnik Vienna and the agricultural experts at ENGIE Netherlands. This technology ensures that carrots, potatoes, onions as well as garlic and sweet potatoes will retain their full flavor and vitamin content even shortly before the next harvest season. Air coolers and/or heaters are used to achieve optimal storage conditions.
Saves electricity: Ammonia instead of brine
The iStorage control system ensures the right "dose" of cool or warm air. iStorage is a system that ENGIE Netherlands developed together with the Agricultural Technical College in Dronten, Netherlands. In order to ensure electricity savings, the cooling system operates using direct evaporators. "We intentionally avoided using brine in the building," explains Peter Kratzer, who supported the project as a sales representative at ENGIE in Vienna. "Ammonia can convey the same thermal energy to the consumers at a fraction of the required brine volume."
Evaporators offer large air throw distances
The job of the evaporators in the storage facilities is handled by 23 units from Kelvion GmbH: eleven models from the Goedhart VRB product range and twelve DRS devices. They can cool and also partially heat or be used for condensation drying as required. Their cold source comes from the central refrigeration system with five compressors, and the compressor waste heat is used as the heat source.
Heating, cooling or drying
All Kelvion circulating air coolers are made from durable stainless steel and aluminum, have fans with EC motors and are equipped with energy-saving hot-gas defrosting. The smallest unit circulates up to 14,000 m³ of air per hour, the largest up to approx. 36,000 m³/h. The cooling capacity for the largest versions is up to 45 kW, the thermal output up to 94 kW. The DRS circulating air coolers, which circulate a max. air flow of 42,000 m³/h, provides a cooling capacity of up to 40 kW.
Air conduction adjustment as needed
Evaporators that blow air out on one side are mounted to the front of each cold room in all storage halls except for the carrot storage hall. The large carrot storage hall is an exception due to the centered ceiling arrangement: The air can be blown in the direction of the door as well as in the opposite direction (towards the outside wall) due to the mounting of the units in the center of the hall. This ensures improved flow through the large room. Blue tarps attached to the evaporators prevent the air coming out of the devices being immediately drawn back in.
The air flow in the onion storage hall with its condensation drying is also important. Here the hall air is drawn in via a high performance pressure wall that routes the air through the onion crates through the fin coil and draws off any condensation before the heater can bring the air back to target temperature.
Sustainably grown, sustainably cooled
The evaporators in the cold rooms also help to keep the energy costs low for keeping the vegetables fresh: They ensure the efficient supply of cold or warm air into the room thanks to their heat transfer capacities and large air throw distances. And the use of ammonia as the refrigerant (ODP=0 and GWP=0) enables a climate-neutral, energy-saving climate control of the vegetable warehouse in combination with green energy as auxiliary energy.