Groundwater provides a constant-temperature cooling system that can operate throughout the year and can play a decisive role in the storage and preservation of food. Ökoring Handels GmbH in Mammendorf's utilization of groundwater saves on electricity costs compared to purely conventional cooling systems. Ökoring has understood this principle for a whilst now and is consistently implemented it. For the cooling and heating of a newly constructed hall for the storage of high-quality organic food in 2011/12, regional near-surface groundwater was utilized to feed a cooling system. The hall is differentiated according to different warehouse categories. Thus, the target temperatures of the various cold stores are between 2 to 4 °C (e.g. dairy products), 6 to 8 °C (e.g. lettuce and leaves), or above 10 °C (e.g. bananas). Other areas, such as beverage warehouses, offices and workspaces, in turn, do not have to be cooled, but if necessary, they need seasonal heating. The basic cooling and heating concept is designed so that cooling is achieved primarily and directly with groundwater. At higher air temperatures above 19 °C or larger temperature gradients a conventional chiller is required. In addition, the waste heat from this chiller is used to heat other parts of the building or, optionally, to pre-heat the groundwater side of a heat pump for heating. Here, the coefficient of performance (= COP) of the heat pump can be significantly increased. The system is buffered via heat and cold storage. Due to the special geological and hydrogeological conditions, very thorough planning of the well system with detailed preliminary investigations of the subsoil conditions was essential for the development of groundwater. The site is located on the outermost edge of a chalk gravel pack deposited by the meltwater of the Ampers and their tributaries during the Würm ice age.
This means that the gravel containing the slowly flowing groundwater to the north and northwest gradually thins out from a few meters to centimeters and thus significantly reduces the usable yield. For the reasons mentioned above, the wells and sinks that serve to return the thermally used groundwater had to be positioned on the available surface in such a way that the greatest possible groundwater thicknesses were achieved and that the wells would not adversely affect each other in the hydraulic and thermal processes. For this purpose, a test well was first constructed and the site-specific hydraulic parameters were evaluated with the aid of a pumping test. Subsequently, the subsurface and the groundwater of the site were mapped by means of small caliber probing and groundwater measuring points were set up. The groundwater monitoring stations were used to obtain additional hydraulic data and to monitor the spatial distribution of the subsidence of the groundwater level at the wells or augmentation at the wells during the final test phase. Subsequently, on the basis of the obtained geological and hydraulic data, a further well for groundwater extraction and two downstream wells were prepared in suitable hydraulic-thermal positions and distances and tested by combined pump-swallowing tests. The groundwater was tested for its chemical composition and technical suitability in the first exploration well. The groundwater tests and investigations showed that the maximum power required to cool the hall was 200 kilowatts and the heating power required for heating parts of the hall was 105 kilowatts with a groundwater supply of 10 liters/sec. can be provided.
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