A heat pipe heat exchanger is a row of sealed tubes, each partly filled with a working fluid (often water, ammonia or a refrigerant). One end sits in the exhaust stream, the other in the supply stream. Heat evaporates the fluid at the hot end; the vapour travels to the cold end, condenses, and the liquid returns by capillary action or gravity. Net result: heat moves from exhaust to supply with no moving parts and no mixing of the two airstreams.
Why engineers pick heat pipes
- No cross-contamination: streams stay physically separate, critical for contaminated or hazardous exhaust.
- No moving parts: nothing to wear out, unlike a rotary wheel.
- Flexible orientation: gravity or a capillary wick returns the fluid.
- Inherent frost relief: the cold end can run warmer than a plate core at the same duty.
Where they fit best
| Duty | Why heat pipe |
|---|---|
| Mines / underground | No carryover, robust, low maintenance |
| Kitchen / grease-laden exhaust | Separated streams, washable |
| Pharma / lab exhaust | Zero mixing, compliant |
| Dehumidification assist | U-type heat pipe precools and reheats |
Limits to know
Heat pipes recover sensible heat only (no moisture transfer), and per-unit-area effectiveness is typically lower than a counterflow plate. For enthalpy recovery you need a wheel or desiccant plate. See the plate vs rotary comparison and mine ventilation guide for duty examples.
Specifying a unit for your project?
EN159 builds plate, rotary, heat-pipe and counterflow air-to-air exchangers. Send airflow (m3/h), inlet temperatures and available space and we will size it.
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