A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand.

Thesis (M.Eng.) - Asian Institute of Technology, 1975

Six pilot scale solar stills were designed and constructed for studying production performance characteristics under tropical conditions. The average production rate of the simple conventional solar still was found to be 2.04 l.m-2.day-l at mean solar radiation of 5.1 kw.m-2.day-l The overall efficiency was 25.2 percent. Internal and external mirrors gave 30.0 and 49.0 percent higher production rates respectively but solar stills with depth/width ratios of 1:4 and 1.:3 gave 6. 8 and 47.0 percent less output than the simple solar still with depth/width ratio of 1:8.8. Relationships between solar radiation and production for each unit with different type of feed waters were investigated and it was found that the overall efficiencies increased by 2.2 percent when 3.0 gm.1-l of activated carbon was added into standard sea water. Increasing the turbidity of sea water to 400 JTU resulted in a decrease of 3.2 percent of the overall efficiency. Economic analysis indicated the minimum water cost by solar stills to be 38 ß.m-3 for a 20-year life of still. The production cost was calculated to be 28 ~.m- for a 20-year life of 12,000 l.day-1 installation in Thailand.