Refrigeration below zero °C: Adsorption chillers using water with ethylene glycol as antifreeze

Adsorption chilling with water as working fluid is environmentally friendly, but limited to cooling temperatures above 0°C. To expand the operational range of water based adsorption to and below the freezing point of water, we propose to add ethylene glycol as anti-freezing agent to the evaporator. According to vapour liquid equilibrium data, ethylene glycol remains in the evaporator and thus should not be adsorbed. Therefore, only water is still serving as refrigerant. Experiments generating cooling power at 0°C demonstrate that the adsorption process works with ethylene glycol as anti-freezing agent. Furthermore, measured ethylene glycol concentrations in condenser and evaporator confirm that water serves as refrigerant. The experiments demonstrate the potential of adding anti-freezing agents to the evaporator to expand the application range of water based adsorption chillers.