Korean Researchers Unveil Waste-Heat-Powered Cooling Prototype

Researchers at the Korea Institute of Machinery and Materials (KIMM) have developed a prototype 10 kilowatt chemical adsorption heat pump designed to provide cooling for buildings, factories and data centers using low-grade waste heat. A chemical adsorption heat pump transfers heat using the reversible attraction between a solid adsorbent material and a refrigerant vapor, rather than relying on a conventional electrically powered mechanical compressor.

In the system, heat -- such as industrial waste heat -- releases refrigerant that has been held on the adsorbent's surface. The refrigerant is then condensed, releasing heat, before evaporating at low pressure and absorbing heat from the space or process being cooled; the vapor is then drawn back onto the adsorbent to repeat the cycle. Because heat is the primary energy input, the system needs relatively little electricity, which is used only for auxiliary equipment such as pumps, valves and controls.

The prototype can produce cooling using waste heat at around 40°C, well below the 70°C-plus typically required by conventional adsorption cooling systems, the researchers said. They reported a specific cooling power of 346.5 watts per kilogram, more than double that of comparable international technologies, from a core adsorption bed that holds and releases the refrigerant while transferring heat between the adsorbent and the external heat source.

The system uses an electrochemical compressor with no mechanical moving parts, which the researchers said cuts energy use while generating virtually no noise or vibration, making it suited to hospitals, schools and residential areas. It also uses ammonia, a natural refrigerant, which the team said helps the system comply with international refrigerant regulations.