Dynamic optimization of adsorptive chillers: The “AQSOA™-FAM-Z02 – Water” working pair

• Dynamic optimization of adsorptive chillers with loose FAM-Z02 grains is addressed.
• Water sorption dynamics is studied by a Volumetric Large Temperature Jump method.
• Effects of adsorbent bed thickness, grain size and cycle boundaries are analyzed.
• Recommendations on improving the dynamics of real adsorptive chillers are made.
• Their implementation can lead to more compact chillers utilizing the loose grains.

Despite significant progress in commercial ACs (adsorption chillers) achieved for the last thirty years, still there is a much room for their further improvement. This paper addresses the optimization of dynamic performance of ACs utilizing loose grains of a novel adsorbent AQSOA™-FAM-Z02. The dynamic data were measured by a Volumetric Large Temperature Jump method under typical conditions of isobaric ad/desorption stages of real AC cycle. For the first time, the effects of number of the adsorbent layers (N = 2, 4, and 8), grain size (0.2–0.9 mm) and cycle boundary conditions were comprehensively studied. The most notable findings revealed for the water ad/desorption dynamics are: 1) the initial part of all kinetic curves is exponential and can be described by a single characteristic time τ; 2) at equal values of the ratio (S/m)=(heat transfer surface)/(adsorbent mass), the dynamic curves are very close regardless the adsorbent grain size R (the “grain size insensitive” regime is observed at 0.44 m2/kg ≤ (S/m) ≤ 1.75 m2/kg); 3) the maximal specific cooling power is a linear function of the (S/m)-ratio. Appropriate recommendations on improving the AC cycle dynamics which concern the optimal conversion degree, grain size and (S/m)-ratio are made.