CFD Modelling of an Underground Water Tank Heat Storage System

In this work, CFD is used to simulate the flow in an existing thermal labyrinth located at the basement of a hospital building. This labyrinth is an underground channel equipped with water tanks to increase the thermal mass and reduce the heating and cooling demand of the building. Thermal energy storage in the water tanks is a complex heat transfer phenomena involving turbulent forced convection, solid conduction and natural convection. The turbulent forced convection happens between the water tank outside surface and the air flow through the labyrinth. The heat is then conducted through the tank wall and induces a slow buoyant flow inside the tank. CFD techniques are used to solve these problems and the results are compared with experimental measurements. A simplified analysis is then developed to find the optimum parameters and working conditions for designing such a system in future buildings.