The Turboexpander: A Design, Make and Test Student Project

Third year Engineering students at Cambridge University have to undertake a project, occupying about 80 hours of their time, which should involve designing, making and testing some item of Engineering interest. A turbomachinery based project has been developed to fulfil this requirement. The project is based around a “turboexpander” which consists of a centrifugal compressor and a radial inflow turbine on the same shaft. The compressor takes in air from the atmosphere and delivers it directly to the turbine and the assembly is driven by sucking the turbine exhaust with an industrial vacuum cleaner. The flow path is therefore similar to that used in aircraft air conditioning systems or in most gas liquefaction plant, but with the difference that in these cases the objective is to provide cold air and so the air leaving the compressor is cooled before it is expanded in the turbine.