Abstract Due to the lack of phase-change energy storage modules in the TRNSYS software, this paper applies the numerical simulation method to develop a TRNSYS module. Research has been conducted on the characteristics of the shell-and-tube phase-change energy storage system in order to provide a reasonable basis for its application in practical engineering. According to the principles of energy conservation, a numerical model has been proposed to calculate the temperature field and fluid temperature field of the phase-change unit, and a mathematical model is applied to guide the editing of the TRNSYS module. A Fluent model was established to compare the TRNSYS simulation results and verify the physical validity of the module. In terms of the thermal outlet temperature of the HTF, the maximum relative error between the two in the melting phase is noted to be 1.17%, and the maximum relative error at the solidification stage is 1.83%.Different flow parameters of the system have been studied. The results of the study indicate that differences in inlet temperatures have a greater influence on the average temperature and outlet temperature of the PCM, whereas differing inlet flows have a negligible influence on the phase-change unit.