Performance comparison of two water pit thermal energy storage (PTES) systems using energy, exergy, and stratification indicators

Water pit thermal energy storage systems have been demonstrated in Denmark and proven effective increasing the solar fractions of district heating covering mismatch between heat demand production. This study analyzed five years measurement data for two PTES Denmark, namely Marstal Dronninglund. Their efficiency was assessed using energy, exergy, a seasonal indicator. The degree stratification investigated MIX number, coefficient, newly-introduced indicator, exergy destruction. Exergy destruction shown to be promising indicator assessing since it can used compare with different losses, providing quantitative evaluation amount mixing. In addition, found suitable estimating long-term combined short-term systems. Dronninglund had 92% 73% efficiency, while 63% 48% efficiency. All indicators showed that performed better overall than one Marstal. • Investigation performance evaluated stratification. Seasonal comparing storages operations. worse terms