This paper presents experimental results of forced convection heat transfer and pressure drop across ( 12.5 * 12.5 * 100 cm ) square packed duct. The pad made of forty- eight metallic wrapping coil unit with (0.98 porosity ) and (26 W/m.°C thermal conductivity ). The local surface duct temperature and local heat transfer coefficient
distribution, Nusselt number, pressure drop and friction factor were measured for heat flux (0.56 to 2.73 kW/m2) ,Reynolds number (40339 to 54797 ) and three boundary condition of heat flux imposed on duct surface . It was found that Nusselt number increases as Reynold number, heat flux and number of duct surface exposed to heat flux increases. Nusselt number in packed duct is to be ( 1.2 , 1.19 ) times higher than
the empty ducts at heating all surface and top & bottom surface of packed duct respectively. Many empirical relation between Reynold number, Nusselt number and pressure drop obtained in this study.