Experimental study and performance prediction of the PCM-antifreeze solar thermal system under cold weather conditions

•A novel PCM-antifreeze solar thermal system is proposed and designed.•An experimental setup is built and mathematical model is presented.•The antifreeze performance of the system is analyzed.•Parametric study and seasonal analysis are conducted. This paper proposes a novel PCM-antifreeze solar thermal system which incorporates a specific amount of phase change material (PCM) into the conventional flat-plate solar thermal system (FPSCs) to prevent the system from freezing damage under cold weather conditions. Previous studies about the freeze prevention of the FPSCs mainly focus on the development of the antifreeze auxiliary system (electric or manual) which will reduce the system reliability. This work presents a study for a low cost and effective PCM-antifreeze solar thermal system. The experimental setup is built and the mathematical model is presented for the system. The daytime working and night antifreeze performance of the system are evaluated. Results show that the seasonal average freezing risk index of the PCM system is 8% while the value for conventional system is 66%.