raw · papers · ingested 2026-06-26
Thermodynamic limits of adsorption heat pumps — equilibrium working capacity as the COP bottleneck
Source: https://www.sciencedirect.com/science/article/abs/pii/S135943111836469X
Source: Energy Conversion and Management, 2019 (+ corroborating AHP review, SAGE 2022). Full texts blocked. Credibility: High (peer-reviewed, theoretical). Confidence: medium-high.
Key findings (the counter to the thesis)
- AHP COP is bounded by equilibrium thermodynamics: the working capacity and isotherm shape set the ceiling; step-like/S-shaped isotherms (large uptake at low relative pressure) are “the most appropriate for improving COP.”
- AHP review: “the main bottleneck in the lower COP level is the low adsorption equilibrium amount” — conventional adsorbents COP ~0.85, MOFs (step isotherms, e.g. MOF-801) ~2.0. The jump is attributed to equilibrium uptake, not geometry.
- Cooling-power equation R = (W·ΔQ·η_c·ΔH/τ)·η_h: SCP is proportional to equilibrium working capacity ΔQ (alongside cycle time τ) — so capacity is a first-order multiplicative term in SCP, not separable.
Important honesty note
The opposing case is about equilibrium working-capacity step, NOT raw BET surface area. Record performers (EMM-8: COP 0.85 at modest 880 m²/g, low enthalpy) and MIL-101 composites (SCP up despite −37% BET area) show the surface-area-maximization version of the counter-thesis largely fails — which actually supports the thesis’s “not surface area” clause.
Relevance
Steelmans the opposition for fractal-hierarchical-bed-geometry: COP is capacity/isotherm-driven and SCP ∝ ΔQ — so the thesis is true for the transport half of SCP, but capacity can’t be dismissed entirely.