International audienceThis work presents the design of a membrane distillation (MD) unit coupled to a refrigeration device. The operation of an MD pilot plant is first tested then modelled using EES software. The range of hot water feed temperature provided by the condenser of the refrigeration device may vary from 25 to 65 °C as needed by the MD unit. The results of the experimental study enable to validate a 1D theoretical model with a maximum deviation of ± 6%. This model is coupled to a heat pump model to simulate the operation of a coupled machine. The system performance is studied following two scenarios. In Scenario 1 (continuous mode), the system is connected to a seawater network. In Scenario 2 (batch mode), the seawater reservoir is filled up manually every day. The simulation study shows that the increase of the feed water temperature enhances significantly the produced permeate flux but decreases the performance of the heat pump. This system exhibits high exergy efficiency and GOR for a high feed water temperature. Exergy efficiency and gained output ratio (GOR) decrease as the water flow increases and the hot water temperature decreases. Conversely, the coefficient of performance (COP) of the refrigerator increases

Highlights  A model of a CO2 heat pump is described  A first model simulates a heat pump for simultaneous heating and cooling  A second model simulates a heat pump for simultaneous cooling and desalination  CO2 proposes new interesting applications for multi-function heat pumps