RE-WITCH: D6.1 - Optimized components design for industrial adsorption chiller

D6.1 Optimized components design for industrial adsorption chiller, reports the activities performed in the first part of WP6 aiming at the design and optimization of the components for the RE-WITCH adsorption chiller. Regarding the adsorber, which represents the core components of any adsorption machine, comprising a heat exchanger filled with adsorbent material to perform the working cycle under the specific operating conditions, two main activities were carried out. At first, different adsorbent materials were analysed to evaluate their possible thermodynamic performance under the RE-WITCH relevant boundary conditions. Given the market availability and the low cost, microporous silica gel will be employed, but, at least from the thermodynamic point of view, some other interesting options were highlighted that deserve future investigation. Secondly, the HEX selection was performed. Following a techno-economic assessment, the finned-coils HEX technology was considered as the most reliable for the prototype development. A preliminary design supported by CFD modelling was carried out, to analyse the impact of the fin spacing on the achievable specific power of the technology. Further modelling will be carried out in the next months to refine this investigation and provide an optimal geometry for the final prototype design. The other critical component investigated is the refrigerant pump. Indeed, in the specific design of RE-WITCH, the water employed as refrigerant, is being pumped inside the refrigerant circuit at extremely low pressure, thus risking to face cavitation issues. Two different solutions were investigated. For centrifugal pumps, a control system was developed, based on acoustic sensors used to identify the starting point of the cavitation and then, through a feedback loop, managing the speed of the pump to avoid the instauration of the cavitation regime. The second option relies on a submersible pump, directly integrated in the vacuum circuit, that does not suffer of major issues related to the cavitation but needs to be monitored in its operation under vacuum. The best solution will be selected during the design phase of the first prototype. Finally, other components such as automatic vacuum valves, evacuation system and vacuum vessel adsorber reactor were investigated and selected for the upcoming complete design of the prototype.