. And permute of stainless steel mesh (a) Five thickness of the stainless wire-net porous insert (H) operated in the present study were 2, 4, 6, 8 and 10 layer. Three inlet temperature (Ti) consisting of 50, 60 and 70 oC were examined. From the experiment, it was found that the value of Nu trended to increase as increasing Vi, H and Ti. The P was increased with H only but P was not changed with the effect of Vi and Ti. In the comparison, effect of PPI, it was explicit that the Nu of PPI = 10 was greater than the case of PPI = 8. It was clarified by a higher material volume of PPI = 10 leading to gain more energy absorption from a hot air. Then, a higher heat transfer to the pipe surface was achieved. The P of PPI = 10 was higher than the case of PPI = 8. This was based on natural phenomena because the increasing of P was obtained if the fluid flow passed the obstruction.