Edinburgh Napier University

  This paper outlines initial findings from the design of a Thermal Energy Storage
(TES) system whose principal objective is to promote stratification when charged by an
intermittent electrical supply. This concept will offer an efficient solution to the heating and
provision of domestic hot water within buildings when coupled with a renewable energy
source such as wind power.
The principal of operation is to add the energy to the tank through a side arm that
creates a thermosyphon and returns the water to the top of the tank at a desired temperature.
A system of extraction points will then be employed to prioritise the replenishment of
individual tank nodes from top to bottom, thus increasing the useful energy content of the
system.
In this paper initial investigations on the control mechanism required to achieve the
desired mass flow rate have been carried out experimentally on a 750litre tank. The tank was
charged under steady input power with different valve opening angles, the results from which
show the formation of temperature gradients through the tank’s vertical plane.
It is found that the importance of the valve opening lies mainly in permitting large
changes in the power inputs to the store. It also allows for small and large temperature rises
to be achieved across the side arm, thus enabling nodes to be “topped-up”. The requirements
to compensate for the changes in driving force are found to be less critical than first
anticipated.