Due to its unique thermal properties, carbon nanotubes (CNTs) have been used as additives in order to increase thermal conductivity and other mechanical properties of nanofluids. There have been many studies of thermal conductivity for single phase fluids containing CNTs; however, most commercial coolants are two-phase fluids, such as the mixture of ethylene glycol and water (E/W). Similarly, there are some models that can be used to predict thermal conductivity of single phase fluids containing CNTs but not yet as a model for thermal conductivity of the E/W solution containing CNTs. In this paper, we present a model to predict the thermal conductivity of CNTs nanofluids based on an E/W solution. The model is found to correctly predict trends observed in experimental data of V. Kumaresan, et al. with varying concentrations of CNTs in nanofluids.