Stratification Efficiency of Thermal Energy Storage Systems – A new KPI based on Dynamic Hardware in the Loop Testing - Part I: Test Procedure
A test method is introduced and a key performance indicator for stratification efficiency is defined based on the second law of thermodynamics, i.e. on the entropy balance of the storage system. The laboratory test is based on a 24 hour cycle where realistic and dynamic charging and discharging is applied according to boundary conditions of real weather data of a day in the year. This particular day of the year was chosen because of its representativeness for the effect of stratification on the system performance, such that the annual performance can be derived directly from the performance shown in the 24 h test cycle.