Heat Pipe & Vapor Chamber

Passive two-phase heat-transfer conduit using liquid evaporation, vapor flow, and capillary wick return.

Specifications & Metrics

type: Thermal Management Device
governing equation: ΔP_capillary ≥ ΔP_liquid + ΔP_vapor + ΔP_gravity (capillary pumping limit)
primary function: Near-isothermal high-flux heat transport with zero moving parts or external power
key parameters: Effective thermal conductivity (10–100 kW/(m·K)), capillary wick pore radius, latent heat of vaporization
originator: R. S. Gaugler (1942 patent) & George M. Grover (1963 Los Alamos National Laboratory)

Conceived by R. S. Gaugler in 1942 and independently developed and named in 1963 by George Grover at Los Alamos National Laboratory for space nuclear reactors, a heat pipe seals a saturated working fluid inside an evacuated envelope lined with a capillary wick.
Heat absorbed at the evaporator vaporizes the liquid; the resulting vapor pressure differential drives vapor rapidly to the condenser to release its latent heat of vaporization, and capillary forces in the sintered or grooved wick pump condensate back to the hot end even in zero gravity.
Copper–water heat pipes and planar vapor chambers (20–150 °C) cool laptop CPUs and GPUs at effective thermal conductivities 10 to 250 times that of solid copper, while aluminum–ammonia variable-conductance heat pipes regulate satellites and 12-meter thermosyphons keep permafrost frozen beneath the Trans-Alaska Pipeline.