An　experiment　was　performed　to　study　the　heat　transfer　characteristics　of　liquid　flow　through　two　multi-port　extruded　(MPE)　micro-tubes　with　water,　ethanol,　acetone　and　ethanol/water　mixtures.　The　cross-section　geometries　of　two　tubes　were　rectangular　(approximate　square)　and　circular,　and　with　hydraulic　diameters　of　0.72　and　0.86　mm　respectively.　The　results　showed　that　at　Reynolds　number　(Re)　below　500,　Nusselt　number　(Nu)　decreased　with　increasing　heat　flux　but　Nu　approached　a　minimum　for　increasing　heat　flux　at　Re　＞　500.　Experimental　results　showed　that　such　change　was　caused　by　the　effect　of　entrance　function　and　conjugate　heat　transfer.　The　experimental　Nu　of　the　circular　multi-tube　was　higher　than　that　of　rectangular　multi-tube.　For　ethanol,　pressure　drop　decreased　dramatically　with　increasing　thermal　resistance　beginning　at　a　low　thermal　resistance.　Additionally,　the　higher　the　inlet　temperature,　the　smaller　the　slope　of　pressure　drop　decrease　against　thermal　resistance.　Further　investigations　of　water,　ethanol　and　acetone　were　conducted.　Nu　of　ethanol　were　highest　and　those　of　water　were　the　lowest　among　three　solutions　with　the　same　heat　flux　and　inlet　temperature.　Experiments　of　rectangular　multi-tube,　with　different　mixing　ratios　of　ethanol/water　showed　that　the　trend　of　Nu　against　Re　remained　unchanged　at　low　ethanol　concentration.　Furthermore,　the　higher　the　ethanol　concentration,　the　faster　the　growth　rate　of　Nu　against　Re　and　the　greater　the　Nu　difference　between　adjacent　concentrations.　Theoretical　reasons　for　this　remains　to　be　further　studied.　©,　2014,　Chemical　Industry　Press.　All　right　reserved.