Techno-economic evaluation of novel absorption refrigerator-driven membrane distillation plants

Reducing the energy consumption of desalination plants and air-conditioning systems is primely important for efficient systems and less carbon emissions. As thermally driven systems, vapor-absorption refrigeration systems and direct contact membrane distillation plants could be integrated to minimize energy consumption. In this regard, the literature has already proposed the integration of such systems but with using only one desalination plant. Thus, the current study integrates two plants of direct contact membrane distillation with a double-effect absorption refrigeration system. One plant is driven by the refrigerator's absorber, and the other is run by the condenser. In such a way, all the energy released from the components of the absorption refrigerator (i.e., evaporator for air-conditioning purposes and absorber and condenser for desalination) is useful. Two schemes of the integrated system are proposed with parallel- and series-multistage direct contact membrane distillation plants. For the implemented conditions, it is shown that the proposed systems produce more freshwater than the standalone membrane distillation plants. The economic analysis also demonstrates that the freshwater and cooling effect costs are lower than the standalone systems by more than threefold. Furthermore, the proposed systems show better performance than those reported in the literature. It is also shown that the parallel-multistage integrated system performs more efficiently than the series one under optimal conditions. For instance, the parallel-multistage integrated system has a water production of 1635.0 L/h, a gain-output ratio (GOR) of 2.730, a cooling effect of 117.50 ton of refrigeration (TR), a coefficient of performance (COP) of 1.034, an overall thermal performance (energy utilization factor, EUF) of 3.764, a water cost of 3.530 $/m³, and a cooling cost of 0.0044 $/kWh.