Friction Expander for the Generation of Electricity (FEGE)

Abstract

At present and in future the necessity of generating electricity  using  renewable  resources  globally  is  most  important and   clearly   evident.   Depending   on   how   the   scenarios   are designed  and  disregarding  fossil  resources  the  contributions  of renewable  energy  sources  have  to  be  increased  by  a  factor  of four  to  six  as  far  as  it  concerns  the  installed  capacity  and  the amount   of   electricity   generated.   The   corresponding   annual investment costs amount some hundred billion US-$ and the CO2emission reduction equals one Gt. In any case heat to electricity conversion  systems  based  on  biomass,  geothermal  and  process heat recovery are expected to provide significant contributions to this  objective.  Besides  several  others  the  conversion  technology of a Rankine Cycle Process is most suitable over a wide range of capacities  notwithstanding  the  possibilities  to  applicate  workingfluids  ofnon-organic  or  organic  character.  Particularly  for  the heat  recovery  from  the  exhaust  gas  of  biogas  operated  internal combustion  engines  the  type  of  a  newly  developed  friction expander  was  designed,  constructed,  built  and  evaluated.  Based on  preceding  theoretical  and  numerical  calculations  as  well  as constructional   and   experimental   studies   using   hexane   and hexamethoxydisiloxane  in  the  project  reportedhere  saturated water  steam  was  used  as  working  fluid.  During  the  experiments carried  out  in  a  special  test  facility  the  electric  power  of  the system amounted 1.4 kW representing two thirds of the concept-tual design.