Experimental performance of membrane water absorption in LiBr solution with and without cooling

• Published in: Applied thermal engineering Vol. 180; p. 115786
• Main Authors: de Vega, M., García-Hernando, N., Venegas, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 05.11.2020; Elsevier BV
• Subjects: Absorbers; Absorption systems; Adsorption; Cooling; Cooling rate; Flat sheet membrane; Heat transfer; Mass flow rate; Mass transfer; Membranes; Microchannel-absorber; Microchannels; Pressure; Pressure drop; Stainless steels; Steel plates; Temperature; Thin plates; Water; Water absorption; Water temperature; Water vapor; Water–lithium bromide mixture; Water–lithium bromide mixture; Microchannel-absorber; Flat sheet membrane; Absorption systems
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2020.115786

•Adiabatic and cooled absorption are tested in a membrane microchannel absorber.•LiBr-water adiabatic absorption can operate without the need of a cooling tower.•Adiabatic/cooled behaviour agrees with simulations when varying mass flow rate.•Measured pressure drop is acceptable for the LiBr-water absorption requirements. The operation of a microchannel membrane-based absorber using LiBr-water as absorbent-refrigerant pair is presented. The absorber is a stainless-steel plate structure, provided with microchannels coupled with a membrane which separates the water vapor and the solution. The same device is experimentally tested in two modes of operation. In one, water is used to cool the absorption process (as occurs in conventional absorbers) circulating through channels separated from the solution by a thin plate. In the second mode, no water circulates, and the absorption is adiabatic. The absorption rates obtained using both configurations are compared, evaluating the influence of the solution mass flux. The absorption ratio (absorbed vapor to solution mass flow rate) is studied as a function of the cooling water temperature and its effect on solution temperature and pressure potential. The mass transfer coefficient is inferred from the measurements. Also, the measured pressure drop along the channels shows the viability for the operation of this type of absorber.