DIY absorption cooler achieves 5°C using fire, salt water and solar power
A home-built absorption refrigeration system using water and road salt as refrigerant reached 5°C in testing, with only fire as the primary energy source and minimal electrical needs met by solar.
Summary
Greenhill Forge has built a heat-driven absorption cooler that uses water and road salt rather than conventional refrigerants. The system boils water at low pressure to absorb heat, then condenses the vapor elsewhere. In initial tests it cooled to about 5°C with 16°C ambient temperature. A small solar panel or battery handles pumps and fans; the main energy input is fire heating the saltwater solution.
How the salt-and-fire cooler works
- Refrigerant: Water, with road salt as the absorbent, replacing conventional synthetic refrigerants
- Generator loop: Fire heats a tank of saltwater solution; boiled water vapor rises through a tube to the condenser
- Expansion: A partially opened valve lets condensed water drip into the low-pressure absorber section, where it boils rapidly at reduced pressure and absorbs heat from surroundings
- Absorption loop: A shower of salt solution captures the water vapor and carries it away from the cooled area
- Electrical needs: Minimal; small solar panel or battery sufficient for pumps and fans
- Performance: Reached ~5°C with ~16°C ambient in first tests—below refrigerator target but functional proof of concept
Why it matters
The design offers a path to refrigeration without dependency on compressed gases or grid electricity, potentially useful for off-grid and resource-constrained settings. The use of common materials (road salt, water) rather than specialized refrigerants lowers barriers to replication and repair.
Original reference: hackaday.com →