Heat and mass transfer performance comparison of various absorbers/desorbers towards compact and efficient absorption heat pumps

• Published in: International journal of refrigeration 2021-07, Vol.127, p.203-220
• Main Authors: Zhai, Chong, Wu, Wei
• Format: Article
• Language: English
• Subjects: Absorbers; Absorbeur/désorbeur compact; Absorption; Absorption heat pump; Compact absorber/desorber; Comparaison des performances; Energy utilization; Falling; Geometric accuracy; Heat conductivity; Heat exchangers; Heat pumps; Heat transfer; Heat transfer coefficients; Heat/mass transfer; Mass transfer; Membrane à microcanaux; Membranes; Microchannel membrane; Microchannels; Performance comparison; Plate heat exchangers; Pompe à chaleur à absorption; Pumps; Sorption; Structural design; Studies; Temperature; Transfert de chaleur/de masse; Waste energy utilization
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2021.01.029

•Heat/mass transfer performance of four absorbers/desorbers are compared systematically.•Their heat/mass transfer rate domains are identified in representative geometry ranges.•Microchannel membrane-based structure performs best in both absorbers and desorbers.•The largest heat/mass transfer rates are 8.6 kW m−2 K−1 and 0.015 kg m−2 s−1 for absorber.•The maximum heat/mass transfer rates are 4.2 kW m−2 K−1 and 0.0225 kg m−2 s−1 for desorber. Absorption heat pump (AHP) is significant for renewable/waste energy utilization to alleviate the energy crisis. Compact and energy-efficient AHP is essential for wider applications, and absorbers and desorbers play critical roles. To select the best-performing components for this purpose, heat and mass transfer characteristics are compared for different kinds of absorbers/desorbers, including microchannel membrane-based heat exchanger, plate heat exchanger, falling-film horizontal tube, and falling-film vertical tube. Heat and mass transfer models for each absorber/desorber have been established with validated accuracies. A wide range of geometrical parameters of absorbers/desorbers have been considered to obtain the variations of heat and mass transfer rates of each kind of absorber/desorber. Results indicate that the heat transfer coefficient and sorption rate (absorption/desorption) show a decreasing trend as the volume increases for all absorbers/desorbers. The microchannel membrane-based structure yields overwhelming heat and mass transfer performance in both absorbers and desorbers. The maximum heat transfer coefficient and sorption rate are up to 8.6 kW m−2 K−1 and 0.0150 kg m−2 s−1 for the microchannel membrane-based absorber and 4.2 kW m−2 K−1 and 0.0225 kg m−2 s−1 for the microchannel membrane-based desorber. This work provides a thorough comparison among various absorbers and desorbers and identifies their heat/mass transfer rate domains, facilitating structural design towards compact and efficient AHPs.