Experimental evaluation of a membrane contactor unit used as a desorber/condenser with water/Carrol mixture for absorption heat transformer cycles

A conventional desorber in the Absorption Heat Transformer (AHT) cycle requires a constant heat flux and vacuum pressure conditions to boil the working mixture and separate the working fluid. In this paper, an Air Gap Membrane Distillation (AGMD) unit was adapted as desorber/condenser with water/Carrol mixture in order to demonstrate the feasibility of the desorption process at atmospheric pressure conditions. Two membranes with 0.22 and 0.45 μm pore sizes were used and three temperature levels were tested. The maximum increase in the concentration (ΔX) was 1.54% w/w (from 60.63 to 62.17% w/w) with a membrane with pore size up to 0.45 μm and a solution temperature of 82.7 °C. The maximum thermal process effectiveness was 17.7% (on average) with a membrane with pore size up to 0.22 μm and a solution temperature of 84.4 °C. Due to the corrosion process, a fouling particle by iron oxide was found on the membrane; this fouling layer could promote the “wetting” process in the membrane after a long operating time.