Application Noon   Energy   is   developing   a   Stirling   engine   specifically   to   run   on   concentrated   sunlight.   Sunlight   is   concentrated by   a   parabolic   mirror   that   just   like   a   sunflower,   tracks   the   sun   during   the   day.   The   Stirling   engine   is   suspended   in the mirror's focal point and converts the intense sun heat into clean electricity.        The   combination   of   a   parabolic   mirror   (a   dish)   and   a   Stirling engine   is   called   a   Dish-Stirling   system   and   is   part   of   a   group   of technologies referred to as CSP, Concentrated Solar Power. A   typical   system,   or   unit,   produces   between   3   and   25   kWe nominally.   Although   these   systems   can   be   used   as   stand-alone off-grid   power   generators,   the   idea   is   to   cluster   them   in   huge fields   and   to   produce   industrial   scale   renewable   energy.   The Desertec    foundation    ( www.desertec.org )     has    calculated    and graphically     displayed     how     much     (desert)     area     would     be necessary   to   meet   the   world's   energy   needs.   The   scenario   to generate   (a   large   part   of)   the   European   electricity   demand   in regions   like   North-Africa   or   Andalusia,   is   realistic   and   necessary.   From   technical   point   of   view,   just   one   last hurdle remains preventing large scale deployment: a reliable and efficient Stirling engine. The Stirling engine The   Stirling   engine   was   invented   almost   two   hundred   years ago   (Rev.   Robert   Stirling,   1816)   and   has   been   capturing   the imagination    of    many    engineers    ever    since.    Even    today    the paradox   of   the   seemingly   simple   thermodynamic   cycle   and   the difficulty    of    turning    this    into    a    serious    and    reliable    power producing   machine,   continues   to   intrigue   engineers   and   the scientific community alike. A    Stirling    engine    has    a    closed    thermodynamical    cycle    with heat   supplied   to   it   externally.   The   heat   source   can   be   anything, ranging     from     traditional     fossil     fuels     to     nuclear     power. Obviously   the   heat   source   for   the   new   Noon   Energy   engine   is clean concentrated sunlight. The      thermodynamic      cycle      produces      useful      work      by compressing   a   working   fluid   when   it's   cold   and   expanding   it   when   it's   hot.   As   expansion   of   the   hot   gas   generates more   energy   than   compression   of   the   cold   gas   costs,   net   work   is   produced   that   can,   for   example,   be   converted into kinematic energy of a crankshaft. In   highly   idealised   cycle   descriptions   of   the   Stirling   engine,   cycle   efficiency   equals   ideal   (Carnot)   efficiency. Obviously,   as   any   other   realistic   machine,   the   Stirling   engine   does   not   obtain   this   hypothetical   optimum   and   it does    not    function    according    to    these    simplistic    'text-book' cycles. It   is   true   however   that   Stirling   engines   are   extremely   efficient, if   designed   well.   A   crucial   part   of   the   engine   is   the   regenerator, most      simply      explained      as      a      thermodynamic      'sponge'. Traditionally   it   consists   of   a   stack   of   very   fine   stainless   steel wire   mesh   that   absorbs   heat   from   the   working   fluid   when   it flows   from   the   hot   space   to   the   cold   space   and   releases   this heat   again   to   the   fluid   when   it   returns.   These   processes   take place     under     extreme     conditions:     kiloWatts     of     heat     are transferred   in   a   fraction   of   second,   under   large   temperature gradients     and     rapidly     changing     fluid     properties     (density, viscosity   etc.).   Wire   mesh   is   a   good   choice   to   accommodate these   processes   as   it   has   a   large   surface   area   for   heat   transfer   while   still   compact   (small   hydraulic   radius). However,   'pushing'   the   working   fluid   through   a   stack   fine   wire   mesh   takes   a   considerable   amount   of   energy   and so   the   resulting   regenerator   design   challenge   is   to   find   the   optimal   compromise   between   large   heat   exchange surface and pumping power. To   date   no   (commercial)   engine   features   a   regenerator   that   has   benefitted   from   scientific   calculations.   Design   is based   on   empirical   experience   which   might   or   might   not   be   close   to   an   optimum.   Advanced   full   3D   CFD software   is   not   going   to   provide   an   answer   either:   Even   if   a   (part   of   a)   cycle   could   be   simulated,   no   general design    rules    will    emerge    from    it.    Each    new    configuration    will    have    to    go    through    this    number-crunching black - box, returning an unverifiable answer. Fresh Start Noon   Energy   believes   that   any   good   design   should   start   with   fundamental   knowledge   of   the   physics   involved. Noon    Energy    is    a    specialist    in    the    cycle    thermodynamics    and    has    many    years    of    experience    with    Stirling machines   (engines   and   cryo-coolers)   and   therefore   uniquely   equipped   to   make   a   fresh   start   with   a   revolutionary concept.   For   the   complex   thermodynamic   calculations   Noon   Energy   uses   its   own   proprietary   software   that   was originally   developed   in   collaboration   with   Dr.A.J.Organ   at   the   Engineering   department   of   Cambridge   University. Reliability   and   low   maintenance   are   key   for   a   serious,   industrial   machine   and   Noon   Energy   is   working   with high - tech    partners    throughout    Europe    using    the    latest    insights    in    modern    production    methods.    It    will    be appreciated   that   details   of   the   new   design   have   to   remain   confidential   at   this   moment.   It   can   be   disclosed however   that   the   first   design   is   specified   for   the   thermal   input   of   a   EuroDish   or   other   mirror   structures   of   similar size. 
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