TORC　(Trans-critical　Organic　Rankine　Cycle)　systems　are　a　promising　thermal　conversion　technology.　However,　the　heat　transfer　deterioration　with　the　supercritical　organic　working　fluid　can　affect　the　system　safety.　Heat　transfer　enhanced　tubes　(HTET)　increase　the　heat　transfer　coefficient　which　limits　the　heat　transfer　deterioration　and　improves　TORC　system　safety　and　economy.　However,　the　heat　transfer　enhancement　in　the　various　types　of　tubes　has　not　been　well　quantified　for　equivalent　conditions　with　contradictory　conclusions　affecting　existing　heat　transfer　enhancement　prediction　criteria.　Therefore,　the　present　study　presents　experimental　comparisons　of　the　heat　transfer　of　a　supercritical　organic　working　fluid　(R134a)　in　two　different　types　of　enhanced　tubes　(an　internally　ribbed　tube　and　a　micro-finned　tube)　to　provide　reliable　experimental　data　to　solve　this　contradiction.　A　total　of　14,100　experimental　data　points　were　obtained.　The　results　compare　the　heat　transfer　enhancement,　the　restriction　of　the　buoyancy　induced　heat　transfer　deterioration　and　the　pressure　loss　factor　of　the　tubes.　The　experimental　results　are　then　used　to　evaluate　the　accuracy　and　limitations　of　the　existing　criteria.　Then,　a　more　general　tube　selection　criterion　is　presented　for　TORC　system　enhanced　tube　selection.　(c)　2021　Elsevier　Ltd.　All　rights　reserved.