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Solar Pura: High-efficiency vertical solar still

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Render of the Solar Pura prototype in Fusion 360.
Solar Pura is an appropriate technology project aiming to provide safe drinking water by harnessing the power of the sun.

Around 2 billion people lack access to clean drinking water across the globe and many of those live in arid and remote areas perfect for the implementation of a highly efficient, low cost, small scale solar still. The aim is for it to produce between 5-10 liters of fresh water per day in a sunny climate, enough for a small family’s needs. The design has been optimised to be lightweight, low cost, robust and user friendly. And a scale functional prototype has been built and tested.

Solar Pura is part of my honours thesis in the school of design at RMIT in Melbourne, Australia. It is the culmination of a year of research into creating technology that can empower those caught in the poverty cycle and how by open sourcing designs and solutions we can give people the means to be self sufficient and build resilience for communities in need.

Vertical multiple effect diffusion type solar stills vs basin solar stills

You can learn about the mechanics and history of solar stills here solar stills and here improving basin solar stills and here understanding solar stills. These pages have a lot of great information on how single effect basin solar stills function. This design would have to be the norm for low tech solar distillation.

For my project I developed 5 key design goals to focus my research around:

  • low cost
  • high efficiency
  • mobility
  • robustness
  • usability.

After many experiments and a lot of research I decided that a single effect basin type solar still could not meet these criteria and looked towards more experimental and complex designs. That is how I came across the work of R.V Dunkle and his 1961 paper on the topic of multiple effect diffusion solar stills[1]. As well as contemporary research groups such as Hiroshi Tanaka et al from Japan[2]. As well as researchers from Taiwan national university also exploring this space [3].

The principle behind the vertical multiple effect diffusion solar still is best described visually by the Taiwan nation university group:

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  1. Original mutliple effect diffuser paper
  2. Hiroshi Tanaka home page

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