abstract
Phase change materials (PCMs) have good properties such as high thermal capacity and constant phase
change temperature. Their potential use in solar energy storage is promising. Tests of exposure and
constant flow rate are performed to investigate the thermal performance of a domestic solar water
heater with solar collector coupled phase-change energy storage (DSWHSCPHES). Due to the low thermal
conductivity and high viscosity of PCM, heat transfer in the PCM module is repressed. The thermal
performance of the DSWHSCPHES under exposure is inferior to that of traditional water-in-glass evacuated
tube solar water heaters (TWGETSWH) with an identical collector area. DSWHSCPHES also performs
more efficiently with a constant flow rate than under the condition of exposure. Radiation and
initial water temperature have impacts on system performance; with the increase of proportion of
diffuse to global radiation and/or initial water temperature, system performance deteriorates and vice
versa.