This paper aims at enhancing the boiling and condensation co-existing phase change heat transfer process inside a small and closed space by heat-conduction bridges. The working fluid is deionized water and the copper heat-conduction bridges are machined directly on the boiling surface and connect the boiling and the condensation surface. Three different heat-conduction bridges that are all rectangular pillars of different sizes and layouts are tested. Experiments were carried out to study the influences of working fluid filling ratio, the cross sectional area size of the heat-conduction bridge and the gap between the heat-conduction bridges (the bridge gap) on boiling and condensation co-existing heat transfer inside the small and closed space. Experimental results show that the heat-conduction bridges can greatly enhance the boiling and condensation co-existing heat transfer process. The optimum filling ratio is 50% for 3 type heat-conduction bridges. The boiling, condensation and overall heat transfer coefficient of the heat-conduction bridges whose cross-sectional area is 2 mm x 2 mm and bridge gap is 1 mm (HCB-C) is the largest among the three heat-conduction bridges. (C) 2017 Elsevier Ltd. All rights reserved.