A phase-change energy storage module with a turbulent transport fluid was studied numerically. The forced convection due to the turbulent transport fluid was solved with the k-ε model and coupled with the phase-change solution in the phase-change material (PCM). The numerical results for the turbulent model as well as the phase-change model were first compared separately with turbulent experimental correlations and a purely phase-change solution in the literature, then conjugate numerical calculations for the energy storage module with different cases were conducted. A correlation for the energy storage capacity was derived and its empirical constants were determined by the numerical data. The correlation provided a reference for the module design and parameter optimization.