They contained a "wick" to transport the fluid from one end of the heat pipe to the other. Relying on the energy absorbed and released from the "phase-change" of the fluid, the hollow heat pipe transfers heat at extremely high speed.
Meron itong “wick” na nagdadala ng likido mula sa isang dulo ng heat pipe papunta sa kabilang dulo. Mabilis ang pagpasa ng init sa heat pipe dahil na rin sa “phase change.”