Caldaro (BZ), Italy – April 2018
The Caldaro wine cellar is located on the Strada del Vino, where we can find about 1000 winegrowers. Most of them own less than a hectare used as vineyards; for this reason, cooperation is of central importance.
The fusion of four wine cellars gave rise to the Caldaro one: Erste (1900), Neue (1925), Bauernkellerei (1906) and Jubiläumskellerei (1908).
This wine cellar has been the first in the South Tyrol territory to give a greater importance to quality rather than to quantity. For this reason, during the eighties, it started a slow and progressive reduction of the yield per hectare, going from 200 quintals/hectare to the actual 75.
Nowadays, about 650 associates work a total area of 471 hectares, producing high quality wines with a yearly production of 3.400.000 bottles.
With the radical restructuring interventions in 2018, the production of industrial cold became “Green” thanks to the use of the new transcritical technology with CO2. It is a low-cost natural refrigerant, with a zero environmental impact, neither toxic nor inflammable and always available.
For redundancy reasons, two identical chillers are installed, each one with a 350-kW capacity and 5 compressors, one of which with an inverter.
The chillers are produced by Enex according to a tested principle: the feeding of the liquid refrigerant to the evaporators is due to gravity, i.e. to the difference of density between the liquid (weighting about 1kg/l.) and the vapour (weighting about 1/10 of the liquid). In this way no pumps are necessary and, above all, the difference between evaporation and glycolic water temperature can be reduced to the minimum (1°C, too), in low load conditions.
The total power is 700 kW and the glycolic water is produced at a variable temperature between +1°C and -6°C.
The heat recovery produces sanitary hot water up to 80°C, which is later successively used for cleaning and sterilizing the barrels.
Moreover, the unused heat is thrown again in the environment with exchangers at 50 meters high, not taking up useful space. This is possible thanks to CO2, which is not influenced by the pressure drop due to extended pipes.
Besides being used for the air conditioning of the offices, the refrigerated water is used in the wine cellar for wine production, too. In fact, the low temperature water is used for controlling the fermentation.
In the pictures we can see the two gas coolers placed on the top and the detail of the weld joints on the stainless-steel tubes.
The chillers, cooled with air, are designed for optimizing the efficiency in the maximum load period, in September, despite assuring the maximum capacity also in the period of maximum ambient temperature.
In order to verify their efficiency, the chillers are equipped with an automatic system of data collection. These data are sent to a “cloud” which memorizes them.
The measurements, performed during summer 2018 and during the grape harvest, have allowed us to verify the efficiency of the implants at different conditions.
In this way, it has been possible to verify the efficiency values and compare them with the expected ones, which are in line with the project.
The chillers with CO2 result extremely efficient in all conditions, both at full load during vinification and in functioning with low thermal load.