Distilled Water Production Rate Research Articles

Performance Characteristics of Four Solar Still Designs

Four solar still designs were evaluated based on their condensed water production and solar radiation absorption efficiency. The designs of the four distillation units were: (1) flat bottom reservoir with single inclined glass (SS1), (2) stair-step reservoir with single inclined glass and continuously fed (SS2), (3) flat bottom reservoir with woven wick material on an absorber plate and double inclined glass (SS3), and (4) flat bottom reservoir with woven wick material on an absorber plate, double inclined glass, and continuously fed (SS4). The water surface areas of solar stills SS1, SS3 and SS4 were 0.5 m2 and of SS2 was 1 m2. Water input and condensed water output were measured each day, as well as solar radiation absorbed. Solar energy conversion efficiency for water distillation was evaluated for the four designs. Condensed water production per square meter of the solar still was correlated to the solar energy received to determine if there was a statistically significant correlation. Results showed that all solar stills showed a s1 slope regression coefficient that was statistically different than zero, when determining a correlation between condensed water production and solar radiation. SS2 had an average distilled water production rate of 2.9 L/m2/day followed by SS1 and SS3 at 2.2 L/m2/day. SS4 had a distilled water production rate of 1.2 L/m2/day. The average energy conversion efficiency was 50% for SS2, 36% for SS3, 31% for SS1, and 21% for SS4. To generate 2 L of distilled water per day (the current daily per capita consumption in the United States), it would take less than 0.7 m2 of solar collector surface area. The yearly condensed water production rate, for a still utilizing the SS2 design and the developed prediction model, in Austin, Texas was estimated to be 1290 L of condensed water per square meter of still surface area (341 gal/m2/yr).

Effect of various absorbing materials on the thermal performance of solar stills

There is a strong need to improve the single slope solar still thermal performance and increase the production rate of distilled water. Different types of absorbing materials were used to examine their effect on the yield of solar stills. These absorbing materials are of two types: coated and uncoated porous media (called metallic wiry sponges) and black volcanic rocks. Four identical solar stills were manufactured using locally available materials. The first three solar stills contain black coated and uncoated metallic wiry sponges made from steel quality AISI 430 type, and black rocks collected from Mafraq Area in north-eastern Jordan. The fourth still is used as reference still which contains no absorbing materials (only black painted basin). The results showed that the uncoated sponge has the highest water collection during day time, followed by the black rocks and then coated metallic wiry sponges. On the other hand, the overall average gain in the collected distilled water taking into the consideration the overnight water collections were 28%, 43% and 60% for coated and uncoated metallic wiry sponges and black rocks respectively.

Performance evaluation of a modified design of a single slope solar still

There is a strong need to look at various possible designs that can be implemented to improve the single slope solar still performance through increasing the production rate of distilled water. Design modifications were introduced to the conventional solar still, involving the installation of reflecting mirrors on all interior sides, replacing the flat basin by a step-wise basin, and by coupling the conventional solar still with a sun tracking system. The inclusion of internal mirrors improved the system thermal performance up to 30%, while step-wise basin enhanced the performance up to 180% and finally the coupling of the step-wise basin with sun tracking system gave the highest thermal performance with an average of 380%.

Feasibility study of desalination technology utilizing the temperature difference between seawater and inland atmosphere

A new desalination technology named Desalination Pipeline is proposed. The Desalination Pipeline system enables simultaneously desalination and efficient transport of distilled water by applying the working principle of a heat pipe without its liquid recirculation function. The energy source for the operation of the Desalination Pipeline system is the temperature difference between seawater and inland atmosphere. A formulation for the model calculation of the Desalination Pipeline system is established and verified by a laboratory experiment. And then, an estimation of the production and the transportation rates of distilled water is performed on the basis of the existing enviromnental and climate data of two target regions, Sana'a, the capital of Republic of Yemen, and El-Quren in Hashemite Kingdom of Jordan. The estimation result indicates that the Desalination Pipeline system can supply distilled water through one year for some inland area about 100 km apart from the coastal area at a distilled water production rate of 3.2–35.0 L/min (about 10,000 m3/y) for a pipe with a diameter of 2 m, 19–205 L/min (about 60,000 m3/y) for a pipe with a diameter of 4 m. The latter nearly matches the flow rate through a small qanat 60–1500 L/min.

Energy and mass balances in multiple-effect upward solar distillers with air flow through the last-effect unit

Considerable improvement in productivity may be obtained if water vapor in the last-effect unit is carried away directly by flowing air. The theory of a closed-type upward multiple-effect solar distiller has been modified to that of an open-type device, and the energy and mass balances have been derived. The production rate of distilled water for each effect under various climate, design, and operational conditions may be predicted by simultaneously solving the appropriate equations.

The effects of climatic, design and operational parameters on the performance of wick-type solar distillers

The theory of wick-type solar distillers has been modified. The effects of climatic, design and operating conditions on the modified factor have been investigated experimentally, and a correlation equation derived. The effects of these conditions on the production rate of distilled water have also been presented.