Abstract: A cooling system for a server may include an evaporator that is in thermal communication with the server so that the evaporator absorbs heat generated by the server. An inlet end of a condenser is fluidically connected to an outlet end of the evaporator, whereas an outlet end of the condenser is fluidically connected to an inlet end of the evaporator. A working fluid disposed within the evaporator and the condenser is substantially free of lubricant. The working fluid absorbs heat generated by the server in the evaporator, changing from a liquid phase to a vapor phase. The working fluid releases heat in the condenser, changing from the vapor phase back to the liquid phase. The phase changes of the working fluid in the evaporator and the condenser result in pressure changes sufficient to cause the working fluid to circulate between the evaporator and the condenser in a self-sustaining, phase-change thermodynamic cycle.