In this study, the phase diagrams for the binary systems of n-C11H24-n-C14H30, n-C12H26-n-C13H28, n-C12H26-n-C14H30, and n-C13H28-n-C15H32 were experimentally investigated to employ potential phase change materials (PCMs) for cryogenic applications. Besides, the phase diagrams were theoretically obtained on the basis of the ideal solubility and UNIFAC models, and the UNIQUAC, Wilson, and NRTL models were applied to build correlations between experimental and predicting values. The results show that the compositions of the eutectic points appear at 10 wt % C-14 for the C-11-C-14 system, 17.8 wt % C-13 for the C-12-C-13 system, 18 wt % C-14 for the C-12-C-14 system, and 10 wt % C-15 for the C-13-C-15 system with eutectic temperatures of 246.85, 257.75, 260.45, and 265.55 K, respectively. Moreover, the melting temperatures calculated using the theoretical models are in good agreement with the experimental results. The average relative deviations for the C-11-C-14 system and C-13-C-15 systems are merely 0.3814% and 0.3220%, respectively, by using the NRTL model. Simultaneously, the minimum relative deviations for the C-12-C-13 and C-12-C-14 binary systems are 0.3649% for the ideal solubility model and 0.4856% for the UNIFAC model. Finally, upon comparing the predicted results of the studied binary systems using the results of the five models, we find that the UNIFAC model provides the most accurate results for the melting temperatures.