Disturbance of Stratification Caused by Direct Horizontal Inlets into a Water Storage Tank

Haller, Michel, Mojic, Igor, Kaufmann, Matthias, Huggenberger, Andreas, Podhradsky, Jason, Frank, Elimar, Lötscher, Lukas, Boller, Simon, Meier, Boris

EuroSun 2014 · Aix-le-Bains, France · 2014-09-16
Published by International Solar Energy Society (ISES)
DOI: 10.18086/eurosun.2014.10.13

Abstract

Water based combi-storages are frequently used in Central Europe for storing heat for space heating and domestic hot water in one device. The stratification efficiency of direct combi-storage inlets has a decisive influence on the energetic efficiency of solar thermal systems and even more of heat pumps that are connected to combi-storages. However, there are currently no simple recommendations for the geometrical design of direct storage inlets together with scientifically supported values for maximum mass flow rates that can be used for charging without disturbing stratification in the storage. In this work, the effect of different geometrical designs and mass flow rates on stratification of the storage was studied for direct storage inlets with computational fluid dynamics. Selected experiments were validated with laboratory tests.

Keywords

Combi-storage, Stratification, Heat pump, Solar thermal, Computational fluid dynamics.

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