Feasibility-constrained thermodynamic analysis of LiBr-H2O and NH3-H2O absorption refrigeration systems
ENERGY, cilt.366, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 366
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.energy.2026.142870
- Dergi Adı: ENERGY
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Compendex, Environment Index, Geobase, INSPEC, Public Affairs Index, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Bursa Uludağ Üniversitesi Adresli: Evet
Özet
Published comparisons of absorption working pairs prescribe the solution heat-exchanger effectiveness, the dead-state composition and a single evaporator temperature independently of the cycle, and some of these specifications cannot be met. This study constrains all three and compares LiBr-H2O with NH3-H2O in one code under identical boundary conditions: generator 75-140 degrees C, evaporator-10 to +10 degrees C, condenser 25-40 degrees C. Of 72 attempted points 54 were solved; the rest are classified by infeasibility. The largest effectiveness at which the exchanger's cold stream stays single-phase falls from 0.771 to 0.495 for LiBr-H2O and from 0.706 to 0.353 for NH3-H2O. It is set by boiling onset, which binds before the terminal approach, so the prescribed 0.70 is unattainable at nine of eleven generator temperatures; crystallization, checked along the strong-solution path, admits two of six lithium bromide designs. Against a declared service (chilled water 12 -> 7 degrees C, 100 kW) neither pair delivers at its nominal evaporator temperature. Meeting the load costs 3.9% of COP for NH3-H2O and 1.0% for LiBr-H2O, and a dew-point ammonia-water evaporator would leave 19.2 K above the entering water. The ranking survives on service-based efficiency, 0.222 against 0.167. Above 0 degrees C LiBr-H2O leads, with COP 0.78 against 0.61 and xi 0.31 against 0.24; below 0 degrees C only NH3-H2O operates. On a chemically complete basis, b = h-T0 s, the absorber leads destruction (33.3%) ahead of the generator (28.7%). NH3-H2O needs 3.4 times the solution-exchanger conductance and LiBr-H2O 278 times the refrigerant-vapour volumetric flow.