raw · papers · ingested 2026-06-19
Progress in design of adsorption refrigeration systems. Evaporators
Source: https://doi.org/10.1051/epjconf/201921302035
Read from local Zotero full-text PDF (group 5183627 / Joule Heist).
Key findings
- Adsorption evaporators operate at low pressure/temperature: 3-20 C and 0.76-2.34 kPa (~1 kPa). At these pressures a liquid column raises local saturation temperature, cutting cooling capacity, so flooded designs are disadvantaged. Three basic types: flooded, capillary-assisted, falling-film.
- Heat-transfer resistance split: ~51% from chilled water to outer tube wall and ~48.8% from outer surface to ambient for smooth tubes; enhancement should target the largest resistance.
- Flooded evaporators: peak cooling capacity at finned-tube immersion depth = 80% of tube diameter (Thimmaiah); larger fin pitch and thicker fins raise heat-transfer coefficient (fin pitches tested 1.6, 3.3, 5.0, 8.0 mm).
- Capillary-assisted (Thimmaiah): Turbo Chil-40 FPI finned tube gave heat-transfer coefficient 596-888 W/(m^2K) at chilled-water 10-20 C, vs 285-365 W/(m^2K) for plain tube. Tubes 3/4” copper alloy C12200.
- Falling-film (the recommended basic type for adsorption chillers): best with staggered bottom-to-top tube arrangement, heat-transfer coefficient up to 7840 W/(m^2K); finned tubes raised coefficient by 62.6%. Korodense/Turbo-CAB 19-26 FPI tubes peaked at 4500 W/(m^2K) vs Reynolds number.
- Turbulators (Thimmaiah): twisted-tape cut heat-flow resistance 12% (COP +10.5%, SCP +9%); Z-type cut resistance 58% (COP +41%, SCP +47%) but pressure drop 14.5x higher (twisted tape 2.5x). Spiral-wire inserts: pressure drop 30-220%, heat-transfer enhancement 50-280%.
- Surface modification: copper-coated tube fins raised heat-transfer coefficient 1.4x with no extra pressure drop, boosting COP +20% and SCP +47.6%. Review concludes falling-film evaporators with extended inner/outer surfaces are the optimal adsorption-chiller design.