Study on heat transfer process of insulated floating cover of water pit for solar seasonal thermal storage

Abstract

Water pit thermal energy storage (PTES) can transfer the solar energy heating from the non-heating season to the heating season, which can efficaciously cope with the mismatch problems in energy intensity, usage time and space of solar energy heating system. The long-term PTES system is stable and efficient, avoiding the idleness and waste of the collector field. The insulating floating cover is the most expensive part of PTES and it is also the key factor to determine whether the thermal stratification of the PTES can be formed. This project studied the heat transfer process of insulated floating cover with a finite element model of a 500 m3 water pit in Yanqing, China, and the result is validated by experimental data. The difference between the numerical simulation consequences and the experimental consequences is about 5.6%, and the comprehensive heat transfer coefficient of the insulated floating cover can reach 0.186 W/(m2 K). The verified numerical model can intuitively display the temperature distribution and other key parameters of the insulating floating cover, which provides an important reference for the design and manufacture of the insulated floating cover.