The　effects　of　vortex　generators　on　heat　transfer　and　pressure　drop　of　a　novel　heat　exchanger　are　investigated　using　computational　fluid　dynamics　(CFD)　method.　The　Reynolds　numbers　based　on　fin　collar　outside　diameter　varied　from　600　to　2600,　the　attack　angle　from　10　degrees　to　50　degrees,　and　the　aspect　ratio　from　1　to　4.　The　numerical　results　are　also　analyzed　from　the　view　point　of　field　synergy　principle,　according　to　which　the　reduction　of　the　intersection　between　velocity　and　temperature　gradient　is　the　basic　mechanism　for　augmentation　of　heat　transfer.　The　results　indicate　that　the　enhanced　configurations　produce　the　longitudinal　vortices　and　accelerate　the　flow,　which　result　in　significant　augmentations　of　heat　transfer　with　modest　pressure　drop　penalties.　It　was　found　that　the　delta-winglet　vortex　generator　with　an　attack　angle　of　20　degrees　and　an　aspect　ratio　of　2　provides　the　best　integrated　performance　over　the　range　of　Reynolds　number　computed.　The　Colburn　j-factor　of　the　optimal　configuration　is　shown　to　increase　by　35.1-45.2%　with　a　corresponding　increase　of　19.3-34.5%　in　the　friction　factor.　(C)　2009　Elsevier　Ltd.　All　rights　reserved.