Example pump systems having dual-function annular heat exchangers are disclosed. An example pump system to pressurize a fluid within a closed loop transport bus includes a pump to move the fluid, a conduit in fluid connection with the pump, a heat exchanger positioned around at least a portion of the conduit, the heat exchanger to receive a first electrical signal transmitted in a first direction at a first time and a second electrical signal transmitted in a second direction at a second time different from the first time, the second direction opposite the first direction.