Performance improvement of a water-purifying absorption cooler through humidification-dehumidification

Abstract

An absorption heat pump that achieves water purification and air-conditioning with secondary water purification through humidification-dehumidification is developed. A thermodynamic model of this cycle is formulated and used to predict cycle performance. The cycle with humidification-dehumidification outperforms similar cycles using forward osmosis and membrane distillation at baseline operating conditions by 19% and 12%, respectively, because of the additional evaporator loads imposed by the humidification-dehumidification process. The performance of the cycle is insensitive to ambient temperature and humidity due to the high air flow rate associated with air conditioning. However, cycle performance is sensitive to the water load once the heat transfer fluid flow rates and heat exchanger sizes have been fixed, demonstrating a 12% decrease in performance when the water output ratio is changed from 7% below the baseline to 7% above the baseline. Designs that allow for on-design or below-design operation will allow excellent cycle performance.