Development and experimental characterization of an innovative adsorption chiller configuration for industrial cooling provision
The industrial sector in the EU accounted for 26.1% of final energy consumption. Electricity represented approximately 33% of this total, with around 150 TWh per year of electricity consumed to operate vapor compression chillers for process cooling—primarily at temperatures above 0°C. In this background, the EU-funded RE-WITCH project is targeting the development and demonstration of innovative solutions exploiting low-grade waste heat, to provide process cooling in different plants, thus reducing the electricity consumption. One of the technologies under development is represented by a novel patented concept of adsorption chiller. It consists of two adsorber reactors working in counterphase, while the refrigerant, i.e. water, is contained in two separate vessels in its liquid phase and is distributed inside each adsorber reactor by means of hydraulic pumps. The refrigerant directly evaporates or condensates inside the adsorber reactor, over a pouring structure, and then carries over the cooling and condensation energy, that is exchanged with the external source and sink by means of plate heat exchangers. A first full-scale prototype, with nominal cooling capacity of 20 kW has been developed. The system uses finned coil heat exchangers as adsorbers, embedded with microporous silica gel as the active adsorbent material. The design follows a modular approach, allowing multiple chiller units to be stacked together to meet the overall cooling demand of the process. Preliminary results are here presented, showing the ability of the technology to achieve up to 0.47 thermal COP with and EER above 30. A thorough characterization will be carried out at lab level in the coming months, to define complete performance map, identify the most effective control strategies to be implemented and identify the proper design improvements to be implemented for the next prototype that will be manufactured for the demonstration campaign in two industrial plants.