## 1 Introduction
Previous research using the NH\({}_{3}\)-H\({}_{2}\)O solution has concluded that the use of membrane contacts contributes to cost and size savings [2; 3; 4; 5; 6]. The present research focuses on the use of membrane-based devices operating with the H\({}_{2}\)O-LiBr solution. This working pair is mainly used for air-conditioning systems and its use avoids the need for a rectification column and attaining higher energy performance. Figure 1: Scheme of a single effect absorption chiller, including conventional shell and tubes exchangers in the desorber and absorber. Some research has been performed related to membrane-based desorbers using the H\({}_{2}\)O-LiBr solution. The authors of [7] tested water vapour permeation and analysed the effects of the temperature difference and stirring rate on the desorption flux. A similar study was conducted by [8] to evaluate water separation from an ultra-thin film of solution. Using a fixed inlet concentration and flow rate, the vapour generation rate was measured, obtaining a linear relation with the heat flux. When the heat flux was fixed, if the inlet mass flow rate lessened, then the concentration increased. Employing the same mixture, [9] showed an enlargement in the desorption rate when the pressure difference across the membrane was increased, and the channel thickness and concentration at the desorber inlet were reduced. A hollow fibre membrane module was used by [10], obtaining experimentally high desorption ratios. The authors arrived to the conclusion that this technology can be used to improve the coefficient of performance (COP) of the chiller or as a novel or secondary desorber capable of using heat at a low temperature. The authors of [11] used a desorber with rectangular microchannels and concluded that pore diameters smaller than 1 micron are valid. In a different work [12], when a comparison to the results of [9] was performed, desorption rates obtained were one order of magnitude higher. More recently, the authors of [13; 14] developed experiments in a desorber-condenser using the air gap membrane distillation technology and the water-Carrol and H\({}_{2}\)O-LiBr working pairs. In this case, the use of this technology provides promising results. The authors of [15] evaluated an intermittent absorption arrangement employing a porous membrane in a desorber-condenser fed with solar thermal energy. In this study, the quantity of refrigerant desorbed was experimentally measured at different operating temperatures. In a recent work, the authors of [16] tested and analysed the effect of the cooling water and solution temperatures on the desorber performance. Using these experimental data, a theoretical heat load was computed and the solar system was sized. In other recent work, the authors of [17] tested a micro-desorber using membrane technology and fed by low temperature heat. Two operating parameters were varied, the hot water inlet temperature (62 and 66 \({}^{\circ}\)C) and the mass flow rate of the inlet solution. The results obtained include the desorption rate, desorption ratio, cooling power, and solution and hot water heat transfer coefficients. With respect to numerical simulation of desorption processes using membranes, the authors of [18] presented a miniature desorber using microchannels. The results obtained using this technology were evaluated for electronics cooling, demonstrating its feasibility. In [19], a combination of numerical and experimental research was employed to evaluate the vapour separation from a solution flowing through microchannels. A numerical model was employed to evaluate the effect of surface microstructures. A different numerical study was developed by [20], using in this case a micro-porous hollow fibre. A cooling capacity of around 2.88 kW was predicted by the simulation and a COP of 0.63 when solution recirculation was used. More recently, a simple model of a membrane desorber using microchannels  
Figure 2: Scheme of a microchannel desorber using microporous flat membranes.