raw · papers · ingested 2026-06-19
Thermodynamic Performance of Adsorption Working Pairs for Low-Temperature Waste Heat Upgrading in Industrial Applications
Source: https://doi.org/10.3390/app11083389
Read from local Zotero full-text PDF (group 5183627 / Joule Heist).
Key findings
- Adsorption heat transformer (AdHT) uses pressure-driven sorption (rich isoster w1, weak isoster w2) to upgrade waste heat: evaporator fed waste heat at T_L produces vapor adsorbed in the bed, releasing upgraded heat Q_A at higher T_A; condenser dumps heat at ambient T_0. COP = Q_A / (Q_L + Q_L’). Useful effect = gross temperature lift (GTL = T_A - T_L).
- Ten working pairs screened (Dubinin-Astakhov equilibrium): water with Siogel silica gel, AQSOA Z02, MWCNT-LiCl, SGST silica gel-LiCl-35; ammonia with AC SRD 1352/2 and AC KOH; ethanol with AC SRD 1352/2 and silica gel-LiBr; methanol with AC Carbotech A35/1 and MWCNT-LiCl. Investigated boundary conditions: waste heat 40-80 C, ambient -10 to 30 C (min ambient 5 C for water-based to avoid freezing).
- Two-bed configuration (heat recovery between adsorber/desorber) always beats one-bed; with ideal heat recovery (delta-T to 0 K) it raises COP for a given GTL. A realistic delta-T = 5 K markedly degrades performance for 40 C waste heat: only ~10 K GTL achievable at minimum acceptable COP ~0.3 and very low specific energy ~20 kJ/kg when ambient is 5 C.
- At 80 C waste heat with delta-T = 5 K, up to ~52 K of GTL achievable at COP 0.3, though with specific energy below ~50 kJ/kg; AQSOA Z02/water reaches COP ~0.5 plateau.
- Best performers at 40 C waste heat / 10 K GTL: SGST-LiCl/water (COP > 0.45 at 5-10 C ambient, specific energy 200-400 kJ/kg) and MWCNT-LiCl/methanol (extremely high specific energy ~1500 kJ/kg below 0 C ambient, >400 kJ/kg at 5 C). MWCNT-LiCl/methanol also gives 20 K GTL with 1040 kJ/kg at -10 C and 940 kJ/kg at 0 C.
- At 50 C waste heat (Table 4), MWCNT-LiCl/methanol dominates: 10 K GTL gives 1658.80 kJ/kg / COP 0.50 at 5 C ambient and 1436.81 kJ/kg / 0.50 at 10 C; 20 K GTL gives 1041.36 kJ/kg / 0.50 at 5 C. SGST-LiCl-35/water at 10 K GTL gives 705.51 kJ/kg / 0.50 (5 C) and 520.56 kJ/kg / 0.49 (10 C).
- Ammonia pairs (AC SRD 1352-2, AC KOH) sustain GTLs up to 30 K (COP > 0.4, >100 kJ/kg at -10 C ambient) but never exceed ~380 kJ/kg specific energy. Pure adsorbents are too weak above 0 C ambient; composite salt-in-matrix sorbents are concluded to be the most promising AdHT materials due to their much higher sorption capacity and specific energy.