SimplifiedoptimumsizingandcostanalysisforcompactheatexchangerinVHTROriginalResearchArticle

Inthisstudy,theoptimumsizeofthecompactheatexchangerhasbeendevelopedbasedonitsweightandpumpingpowerforthereferencedesignof600MWtveryhightemperaturegas-cooledreactor(VHTR)system.Alloy617wasselectedasaconstructionmaterial.TheoptimumsizeandanumberofconfigurationsforthereferencedesignoftheVHTRwithanintermediateheatexchanger(IHX)wereinvestigatedandourinitialcalculationsindicatedthatithasanunrealisticallytoolargeaspectratioofthelengthandheightduetoitssmall-sizedchannels,whichmightcausemanifoldingproblemsandalargenumberofparallelmoduleswithhighthermalstress.Theflowareaandchanneldiameterwerethenadjustedtoachieveasmalleraspectratiointhispaper.Achievementofthisaspectratioresultedinhighercost,butthecostincreasewaslessthanwouldhaveoccurredbysimplyreducingtheflowareabyitself.Theappropriatechanneldiameterisestimatedtobelessthan5.00mmforthereferencesystem.Theeffectofchannelwavinessenhancedthecompactnessandheattransferperformance,butunfavorablyincreasedtheaspectratio.Therefore,thewavinessshouldbecarefullydeterminedbasedonperformanceandeconomics.Inthisstudy,thewavinessoftheIHXisrecommendedtobeselectedbetween1.0and2.5.Calculationsshowthatreducingthedutydramaticallydecreasestheaspectratio,indicatingthatthecompactheatexchangeriseasytobeoptimallydesignedforlowduty,butmanymodulesarerequiredforhighdutyoperationproportionaltotheoperatingpower.Finally,theeffectofworkingfluidswasinvestigated,anditrevealsthatusingcarbondioxideinsteadofheliuminthesecondarysidereducesthesizeandcostbyabout20%duetothelowerpumpingpowerinspiteofitslowerheattransfercapabilitybyafactorof4.