The　two-phase　frictional　pressure　drop　of　nitrogen　under　diabatic　and　adiabatic　conditions　is　investigated　experimentally　in　two　horizontal　mini　channels.　The　effects　of　factors　in　a　variety,　including　the　channel　diameter,　mass　flux,　heat　flux,　inlet　pressure　and　vapor　quality　are　examined　on　the　frictional　pressure　drop　and　liquid-phase　multiplier　of　the　two-phase　flow.　The　two-phase　frictional　pressure　drop　predicted　by　previous　correlations　from　other　studies　are　compared　with　the　experimental　results　of　this　study,　and　the　lowest　mean　absolute　deviation　is　18.3%　for　adiabatic　conditions　and　10.9%　for　adiabatic　conditions.　Based　on　the　experimental　results　of　nitrogen　flow,　two　new　correlations　in　the　form　of　the　Chisholm-C　correlation　are　developed　to　predict　the　two-phase　frictional　pressure　dropby　involving　the　effect　of　surface　tension,　and　the　mean　absolute　deviation　of　which　is　12.3%　and　10.4%　for　the　adiabatic　and　diabatic　conditions　respectively.　The　new　correlations　are　also　shown　able　to　well　predict　the　experimental　frictional　pressure　drop　of　other　studies　under　different　experimental　conditions.　©　2019　Elsevier　Ltd