Performance simulation and geometries optimization of microchannel membrane-based absorption heat pump working with ionic liquids

Membrane-based absorption heat pump (MAHP) replaces traditional falling-film absorbers/desorbers with membrane-based modules, showing its merits in size reduction and heat/mass transfer enhancement. This paper applies the microchannel technology to further improve these two merits of MAHP. Meanwhile, ionic liquids (ILs) mixtures are used as working fluids to avoid the crystallization. The performance of microchannel MAHP system using H2O/[DMIM][DMP] is simulated under various operating conditions and compared with H2O/LiBr. Results show that the applicability of H2O/LiBr is constrained by crystallization at high 𝑇_ℎ, and H2O/[DMIM][DMP] is limited at high 𝑇_𝑐𝑤. Besides, H2O/[DMIM][DMP] performs better in cooling COP than H2O/LiBr when 𝑇_ℎ>94°C or 𝑇_𝑒>7°C. Finally, by optimizing the geometrical parameters of microchannel membrane-based absorbers/desorbers in MAHP cycle working with H2O/[DMIM][DMP], a Pareto frontier is obtained to provide the balance guidance between the compactness and COP for reasonable microchannel MAHP geometry design.