This paper presents an experimental investigation on nucleate pool boiling of saturated deionized water from uncoated and self-made sintered coated porous tubes with the heat flux from 0.1 to 160 kW·m-2.The influences of the orientation(vertical and horizontal)and diameter(20

25 and 32 mm)of the heating tube and the coating particle size(between 30 and 105 μm)on the nucleate pool boiling were investigated.The results show that the sintered porous coatings can lower the incipient boiling superheat and enhance nucleate boiling heat transfer coefficient compared with smooth surfaces.The incipient boiling superheat of deionized water drops from 4-5 K with the smooth tubes to 1-2.5 K with the porous coated tubes.And the nucleate heat transfer coefficient on porous coating tubes are 3-4.5 times those of smooth tubes.It is found that

at high heat flux

the horizontal tube presents better boiling performance than the vertical tube due to the decrease in bubble slug formation on the tube surface and easy access of liquid to the surface.In addition

the influence of tube orientation on boiling performance is smaller for the porous tube than for smooth tubes.The heat transfer coefficients on smooth tubes and porous tubes decrease as the tube diameter increases.The data for different porous coatings suggest that small particle has slight effect on boiling heat transfer and greater enhancement is found with larger particle size.