Experimental Validation of Thermal Performance of Phase Change Radiator and Application in Solar Heating Systems

• A novel phase change radiator (PCR) integrates heating and thermal energy storage. • PCR maintains indoor temperature above 16 °C during nighttime heating interruptions. • Solar fraction increased from 39.0 to 53.5% in January with PCR integration. • Annual primary energy savings reach 33.2%, with 2098.30 kg of CO₂ emissions reduced. • Payback period is 5.27 years, indicating strong economic and environmental benefits. To meet the low-cost heating demand in solar-rich regions, we utilized phase change thermal storage technology to temporarily store excess solar heat during the day and release it at night to improve the energy efficiency. The optimal placement of phase change material was explored, and a phase change radiator (PCR) was proposed. The heating performance of the PCR under typical winter operating conditions was verified through experiments. Using a standalone building in Lhasa as a case, the TRNSYS simulation was employed to assess the economic and environmental benefits of the Solar-PCR heating system under intermittent heating conditions in winter. The results show that the PCR effectively slows down the indoor temperature drop under intermittent heating and maintains the room temperature above 16°C at night. An increase in the supply water temperature can shorten the phase change time and accelerate the rate of room temperature rise, whereas supply water flow rate has a smaller impact on indoor temperature. Furthermore, in January, the PCR application in solar heating systems improves the solar fraction compared to a conventional radiator (CR) from 39.0% to 53.5%, with an annual energy saving rate of 33.2% and a reduction in CO 2 emissions by 2098.3 kg.