Performance investigation of an integrated collector-storage solar water heater based on lap-joint-type micro-heat pipe arrays

This study investigates a proposed novel integrated collector-storage solar water heater (ICSSWH) combined with lap-joint-type micro-heat pipe arrays (MHPAs) and latent heat storage. In the proposed system, the solar energy irradiated on ICSSWH is collected and stored in a phase-change material via MHPA with fins attached to the storage section inside the heat storage tank (HST). The stored thermal energy is transferred to the water supply by two multi-channel flat tubes attached to the extraction section of MHPA outside the HST. The effects of environmental conditions during the four seasons and the flow rate and inlet temperature of the water supply on the thermal response of ICSSWH are reported. The highest efficiency reached 61.5% and the average extraction power and average outlet temperature reached 1323.3 W and 42.1 degrees C, respectively. The thermal storage efficiency of the proposed ICSSWH is evaluated by using the normalized mean charging efficiency curve, the intercept and slope of which are 0.682 and 4.847 WK/m(2), respectively. Furthermore, mathematical fitting is performed to obtain the function between the mean outlet temperature or extraction power and inlet temperature or volume flow rate during the thermal release process.