Experimental evaluation of a membrane-based microchannel desorber operating at low desorption temperatures

• Published in: Applied thermal engineering Vol. 167; p. 114781
• Main Authors: Venegas, M., García-Hernando, N., de Vega, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 25.02.2020; Elsevier BV
• Subjects: Cooling rate; Desorber; Desorption; Diameters; H2O–LiBr; Heat transfer; Heat transfer coefficients; Hot water; Inlet temperature; Low temperature; Low temperature heat; Mass flow rate; Mass transfer; Membranes; Microchannels; Parameter modification; Rectangular microchannels; Stainless steel; Stainless steels; Steel plates; Temperature; Working fluids; H2O–LiBr; Membranes; Low temperature heat; Rectangular microchannels; Desorber
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2019.114781

•A novel membrane-based microchannel desorber is experimentally tested.•Hot water at low temperature, 62 and 66 °C, has been used as heating source.•The effective desorption area takes up between 85 and 89% of the real contact area.•Real desorption rates ranged between 1.6⋅10−3 and 4.2⋅10−3 kg/m2 s.•The ratio between cooling power and desorber volume reaches 415 kW/m3. A membrane-based micro-desorber prototype fed by low temperature heat is experimentally evaluated. Working fluid is H2O–LiBr solution and it flows along 50 rectangular microchannels of 3 mm width, 0.15 mm height and 58 mm length, manufactured on a stainless steel plate. The effective volume of the micro-desorber is 104.6 cm3. Hot water flows countercurrently through identical channels manufactured on the opposite side of the plate. A microporous polytetraphluoroethylene (PTFE) membrane of pore diameter 0.45 µm is used to separate the solution from the vapour. Two operating parameters are modified, comprising the inlet solution mass flow rate, between 0.5 and 1.7 kg/h, and the hot water inlet temperature, using 62 and 66 °C. The solution is heated in the first part of the channels until desorption starts. The solution concentration and temperature measured at the inlet and outlet allowed the evaluation of the mass transfer performance of the micro-desorber. Results obtained for the desorption ratio, desorption rate, hot water and solution heat transfer coefficients and cooling power are provided.