Modelling of vacuum membrane distillation

A new method of measuring the properties of hollow fibre membranes for modelling purposes was developed. Measuring the gas permeability as a function of membrane length and extrapolating to zero length provided enough membrane material information for modelling the flux. These values resulted in the predicted Vacuum Membrane Distillation (VMD) flux within the experimental errors (±5%) for different velocities. The predicted results at different temperatures were mostly within the experimental variation range. However, the error (<10%) was greater at the highest temperature tested, perhaps due to water evaporation in the feed tank. Additionally both the modelling and experimental results show that the flux in VMD was independent of the module packing density under the presented conditions. The results also show that the mathematical model predictions agree well with the experimental results of short experimental duration (1–2 h).

► A mathematical model is developed for hollow fibre VMD using membrane permeability.
► Length dependency of the permeability of hollow fibre is minimised mathematically.
► Modelling results are assessed experimentally under various conditions.
► Error analysis is conducted based on modelling and experimental conditions.