Novel integration of a parallel-multistage direct contact membrane distillation plant with a double-effect absorption refrigeration system

Abstract

The increasing demand for freshwater and air conditioning triggered the search for more innovative solutions to reduce energy consumption. In this regard, this paper suggests a novel system to drive a direct contact membrane distillation (DCMD) plant by the heat released from the condenser and absorber of a double-effect vapor-absorption refrigeration (VAR) system. The suggested VAR system plays two roles: a heat pump to drive the DCMD plant and a refrigerator for air conditioning purposes. Multiple modules arranged in parallel for one DCMD plant are considered. The integrated system was examined at different conditions, and the performance indicators were represented by freshwater production, cooling capacity, gained output ratio (GOR), coefficient of performance (COP), energy utilization factor (EUF), freshwater cost, and cooling cost. For the best-tuned investigated conditions, the results of produced freshwater, cooling effect, GOR, COP, EUF, freshwater cost, and cooling cost are found as 1315 L/h, 123.4 tons of refrigeration (TR), 2.20, 1.09, 3.28, 4.09 $/m3, and 0.0052 $/kWh, respectively. These performance values outperform the standalone DCMD system by about 2.23 times for produced freshwater, 2.29 times for GOR, 3.42 times for EUF, and 2.82 times for freshwater cost. Compared to a standalone refrigerator, the cooling cost of the integrated system is reduced by 2.88 times with a slight sacrifice in cooling capacity and COP by 0.92 and 0.87 times, respectively. Therefore, the proposed system is an excellent candidate for concurrent production of freshwater and air conditioning.