Performance evaluation of a heat pump-driven vacuum humidification-dehumidification desalination system

Abstract

In this study, the vacuum desalination technology coupled with a heat pump was investigated. Two vacuum humidification-dehumidification desalination systems were experimented. The proposed systems involved the over-atmospheric and atmospheric pressure dehumidification operations denoted by Processes 1 and 2, respectively. The more efficient process was determined through a parametric study based on the desalination rate and specific power consumption. The results indicated that decreasing the humidifier pressure and using a heat pump at the optimum value of saline water to air mass flow rate ratio, a maximum desalination rate of 1.12 kg·h−1 (per 1 m2 of solar water heater aperture area) was obtained. Coupling the heat pump to the efficient process had desirable effects on the desalination rate and produced water cost, with a negligible negative impact on the specific power consumption. Although the airflow rate was considered constant in simulation, its fixing was not possible in experimental work. In actual operation, a reduction in airflow rate was occurred by humidifier pressure reduction, which led to system performance reduction. © 2020