Mathematical modeling and sensibility analysis of a solar humidification-dehumidification desalination system considering saturated air

Abstract

Due to factors such as global warming, population growth and environment degradation, access to drinking water has become a problem in many regions of the planet, specially where the weather is dry. Solar desalination by humidification-dehumidification is a method whose energy source is clean and renewable, and is an interesting alternative to purifying salt or brackish water for human consumption. Modeling works of this system may be divided in two groups: those that consider saturated air in the whole system and the ones that do not adopt this consideration and describe mass transfer. In this work, a mathematical model considering saturation was developed to describe a process based in literature. Four model parameters were estimated by minimization of the sum of squared residuals for experimental temperature values throughout the equipment. The proposed model contains fewer parameters than the model described in literature, which does not consider saturated air. The deviance related to temperature experimental data has the same order as the experimental error. The error related to distillate production was more than 48% reduced, if compared to the literature model. After the validation of the model, a sensibility analysis was made regarding input and project parameters in relation to distillate production. The increase of absorbed heat in the solar collector, the increase of humidifier height and the reduction of seawater mass flow rate were the most significant factors to increase the distillate flow rate. On the other hand, environment temperature variation had little significance in distillate production.