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raw · papers · ingested 2026-06-19

Adsorption Cooler Design, Dynamic Modeling, and Performance Analyses

Source: https://doi.org/10.3390/cleantechnol4040070

Read from local Zotero full-text PDF (group 5183627 / Joule Heist).

Key findings

  • Working pair: granular silica gel RD2060 (Fuji Silysia) / water. Adsorber = cylindrical vacuum chamber housing 50 metal tubes coated/packed with silica gel on their outer surface; heat transfer fluid circulated inside tubes; chamber alternately opened to evaporator or condenser. Adsorbent mass 5.35 kg, tube length 1 m, inner dia 0.01 m.
  • Reference performance: COP 0.5 and SCP 44 W/kg (total cooling power ~235 W) at condenser 30 C, evaporator 15 C, regeneration (hot HTF) 70 C, adsorption HTF 18 C, HTF velocity 0.05 m/s, adsorption time 600 s (warm summer day, Aveiro Portugal).
  • Modeled with a 2D distributed-parameter model (energy + mass balances, Darcy momentum with Blake-Kozeny permeability, LDF uptake kinetics, Toth-type equilibrium isotherm), solved by method of lines / MATLAB ode15s; adapted from validated prior adsorption heating/cooling work.
  • Performance improves with higher evaporator temperature and lower condenser temperature. The cooler still operates on hot days: at condenser 42 C it gives COP 0.31 and SCP 26 W/kg; for refrigeration at evaporator 2 C it gives COP 0.25 and SCP 18 W/kg.
  • Higher regeneration temperature affects SCP more strongly than COP (faster HTF-adsorbent heat exchange); raising regeneration from ~50 to ~90 C steadily raises SCP while COP plateaus near reference value.
  • Cycle-time trade-off: as cycle time increases SCP eventually decreases (longer/more complete cycles do not compensate for added duration); COP and SCP show opposite behaviors for cycle times above ~83 min, so an optimal cycle time must be found per system. Reference cycle ~22.2 min.
  • COP is framed as fair vs vapor compression once the ~40% thermal-to-electric conversion loss of grid electricity is accounted for; AC uses otherwise-wasted solar surplus heat (zero-GWP water refrigerant). Total cooling power scalable by adding adsorbent mass or parallel adsorbers.