Researchers 3D print miniature turbine to test desalination concept
11 November 2015
A team of researchers at GE have 3D printed a 'mini-turbine' using aviation additive manufacturing techniques to test a seawater desalination process.
As part of the water desalination technology being developed with the US Department of Energy, researchers from GE Global Research are using steam turbine turbomachinery, 3D printed in a miniaturised form, to compress and stream a mixture of air, salt and water through a hyper-cooling loop that freezes seawater. By freezing the mixture, the salt naturally separates in solid form, leaving just the ice. The ice is then melted, leaving clean water.
“Some 97.5 percent of the earth’s water supply is virtually inaccessible because water desalination is still too expensive and difficult to deploy at a large scale," says Vitali Lissianski, a chemical engineer and project leader at GE Global Research’s Energy Systems Lab. "By putting desalination ‘on ice’ we hope to change that dynamic. Freezing seawater to treat it is nothing new, but the way we are doing it is very different. We’re tapping into our wealth of technical knowledge in turbomachinery to devise a cost-effective solution.”
“GE’s expertise with multiphase flows in steam turbines is a foundation for the development of a turbine for desalination technology,” says Douglas Hofer, who is leading the development of the turbine technology.
In a low-pressure steam turbine, water vapour condenses to liquid water. For the new desalination process, the GE team is extending that idea to freeze liquid salt water into solid ice and salt crystals during its expansion through the turbine. This extension from condensing liquids to freezing solids requires new and innovative methods to address several challenges of this new turbine application.
“Cooling the salty water, or brine droplets, by expanding cold gas in the turbine would greatly reduce the energy required for desalination," adds Hofer. "The heat transfer between the cooling gas and brine would be much more efficient compared to conventional thermal desalination systems.”
If successful, the process has the potential to reduce the cost of desalination by 20 percent compared with more conventional thermal evaporation approaches.
In order to test their water desalination concept, the researchers effectively shrunk the components of a large, conventional turbine into a usable size for their experiments. To speed the development process, the miniaturised parts were 3D printed using technologies developed in GE Global Research’s Additive Manufacturing Lab and GE Aviation’s additive manufacturing facility in Cincinnati, Ohio.