A　closed　loop　spray　cooling　system　with　R134a　refrigerant　was　designed,　and　experiments　of　cooling　performance　were　conducted　to　make　a　deep　study　on　high　heat　flux　phase　change　spray　cooling　mechanism.　The　experiments　were　conducted　at　the　spray　height　of　13　mm,　the　spray　chamber　pressure　of　0.2　MPa　and　the　inlet　temperature　of　0℃.　The　range　of　flow　rate　was　from　0.2107　L/min　to　0.3558　L/min.　The　results　show　that　the　heat　flux　increases　steadily　with　an　increase　in　the　power　input　when　the　flow　rate　keeps　unchanged.　Moreover,　the　heat　transfer　coefficient　rises　rapidly　first　and　then　fall.　The　heat　flux　has　an　increasing　trend　when　the　flow　rate　increases　form　0.2107　L/min　to　0.3558　L/min,　and　the　maximum　heat　flux　with　value　94.75　W/cm2is　obtained　when　the　flow　rate　is　0.3558　L/min.　Meanwhile,　the　spray　cooling　surface　temperature　keeps　at　35.42℃.　The　results　of　experiments　indicate　that　R134a　has　a　stable　heat　cooling　capacity　as　a　spray　cooling　refrigerant　and　meets　the　requirement　of　high　heat　flux　with　low　temperature　of　cooling　surface.　©,　2015,　Xi＇an　Jiaotong　University.　All　right　reserved.