Here's one paper:
http://www.imwa.info/docs/imwa_2008/IMWA2008_190_Ruehaak.pdf
and another one:
ftp://ftp1.wasy.de/outgoing/IAHR2008_Diersch_et_al_DHI-WASY-HeatPipe-fina.pdf
(this link will only be valid for a few days).
Open-loop systems are very frequently modelled with FEFLOW, but the
engineers designing these systems don't publish very much.
Cheers,
Peter
FEFLOW Support