Design and Heat-Transfer Characteristics of Phase-Change Thermal-Storage Heat Exchanger for Solar Heating Systems

To address the intermittency and instability of solar energy， this study applies industrial-grade paraffin as a phase-change material （PCM） to the field of solar thermal acquisition and heating. An experimental study was conducted to investigate the heat-transfer performance of a finned-tube phase-change thermal-storage heat exchanger under various operating conditions. Specifically， the effects of different inlet water temperatures （45 ℃ and 55 ℃） and flow velocities （0.5， 1.0， and 1.5 m/s） on the fluid's axial temperature distribution， outlet water temperature， and heat-transfer capacity were analyzed. Quantitative calculations were performed for both the instantaneous and total heat-transfer amounts. This study systematically reveals the effects of flow velocity and inlet temperature on the thermal behavior of a phase-change thermal-storage heat exchanger. The results provide experimental evidence and theoretical reference for the development of solar-energy supply–demand regulation devices.