A heat pipe is a sealed copper or aluminum tube containing a small amount of refrigerant that transfers heat through continuous evaporation and condensation cycles, achieving 50-85% heat recovery efficiency. The device contains no moving parts and requires only a temperature difference to operate, making it completely passive. Heat pipes typically transfer 100-500 watts of thermal energy depending on diameter and length.
Technical Details
Heat pipes operate through a two-phase thermodynamic cycle where liquid refrigerant evaporates in the warm section, travels as vapor through the tube, and condenses in the cool section. Standard copper heat pipes range from 10-32 mm diameter and 0.5-2.0 meters in length. Operating temperature ranges span from -40°C to 200°C depending on the working fluid. Pressure differentials between evaporator and condenser sections are typically 0.1-2 bar.
Applications and Practical Significance
Heat pipes are commonly configured in arrays of 4-12 tubes installed vertically through exhaust and supply air streams. They function effectively in moderate climates and clean air applications including office buildings and institutional facilities. Heat pipes are particularly valuable in retrofits because they require no electricity or maintenance. Typical payback periods range from 3-5 years in commercial installations.