A new maritime lifesaving multiple-effect solar still design

This paper presents a new maritime lifesaving multiple-effect solar still design where several extended wicks feed seawater to their evaporating areas by capillary force, and the resulting water vapor diffuses and condenses on facing wicks with the condensate flowing through the wicks into storage bags. A theoretical analysis showed that a temperature drop through diffusion layers between evaporating and condensing wicks slowly increases in the main evaporating areas and rapidly near salt depositions whereas the evaporation rate decreases slowly in the main area and rapidly near salt depositions. These changes are caused by increases in salt concentrations and resulting boiling point elevation. With steady-state transfer analysis, the proposed still is predicted to produce about 15 kg m!2d!1 fresh water on a sunny day of 22 MJm!2d!1 solar radiation, showing a potential to be a maritime lifesaving desalinator.

A new maritime lifesaving multiple-effect solar still design was proposed. Such a solar still is capable of recovering latent heat from condensation and uses it to repeat the distillation process several times. Heat and mass transfer associated with such distillation was theoretically analyzed. The main results of this work may be described as: 1. Along the first wick in contact with the solar absorber and wicks close to the solar absorber, the temperature of wicks rapidly increases near the inlet of seawater and levels off over the main evaporating areas. The temperature increases again near salt deposition on the wicks due to boiling point elevation. 2. While salt concentration from seawater gently increases in the inlet region and in the main evaporating area, it rapidly increases near areas of salt depositions, causing a similar evaluation in boiling point. 3. Temperature drop through vapor-diffusion layers gently increases in the main evaporating area, and it rapidly increases near areas of salt deposition. In contrast, evaporation flux decreases gently in the main evaporation areas, and then rapidly decreases near areas of salt deposition. These are caused by elevation in the boiling point, which increases gently in the main evaporating areas and rapidly near the salt depositions. 4. The proposed still is estimated to produce about 15 kg m!2d!1 of fresh water on a sunny day of 22 MJ m!2d!1 of solar radiation, and such an amount of fresh water production is large enough, exceeding the minimum standards set by SOLAS.