Indirect integration of a thermal–mechanical heat pump with a humidification-dehumidification desalination unit

Abstract

Many previously developed integrated desalination and heat pump cycles have been observed to consume a significant amount of direct electricity supply, raising concerns about their cost effectiveness. To address this issue, this study has modified the performance and cost metrics of the double-effect absorption heat pump cycle combined with a humidification-dehumidification desalination system in terms of configuration. The novelties of the present study are to preheat seawater for desalination utilizing the waste heat of the absorption chiller and to design a doble-effect hybrid thermal–mechanical heat pump. Thermodynamic and thermoeconomic tools were applied to the system. The proposed cooling/desalination system was found to produce 23.23% more freshwater and 47.7% more cooling than a traditional combination. As a result, the current cogeneration unit achieved an energy utilization factor (EUF) of 6.96, which is approximately 17.89% higher than the conventional configuration. Compared to the base case, optimal steam extraction showed a significant improvement of 27.23% in exergy efficiency. Regarding cost metrics, the cost of freshwater was determined to be 2.051 $/m3. As a result, the humidifier has the highest attribution to the overall exergy destruction at 8.98 kW, which represents approximately 16.5% of the total exergy destruction rate.