Non-equilibrium molecular dynamics simulations are used to determine the thermal conductivities of (5,5) single wall carbon nanotubes. By fixing the temperatures of opposing ends of an armchair single wall carbon nanotube with a Nose-Hoover thermostat, the length dependence of thermal conductivities of single wall carbon nanotubes were studied in vacuum. Specifically, single wall carbon nanotubes of 12.3 nm, 24.6 nm, and 36.9 nm lengths with varying fixed end temperatures were analyzed to determine thermal conductivities. In addition, the fixed end temperature lengths of single wall carbon nanotubes were varied to see convergence of the temperature profiles. The equivalent thermal resistance of single wall carbon nanotube bundle in water was modeled using the one dimensional heat conduction equation. The preliminary effective thermal conductivity of the system was calculated with different nanotube structures for a length ranging from 500 nm to 3000 nm to observe effective thermal conductivity variations. The effective thermal conductivity increases when the volume fraction of SWNTs and the nanotube length increase.