Effect of Integral Finned Tube on Heat Transfer Characteristics for Cross Flow Heat Exchanger

Ai: inner surface area of tube (m 2 ), Ao: outer surface area of tube (m 2 ),Cp:, Specific heat of the fluid (J/kg.°C), d: tube diameter (m), hi: inner side heat transfer coefficient (W/m 2 .°C), Rea: air side Reynolds number, ho: air side heat transfer coefficient (W/m 2 .°C), hof: air side heat transfer coefficient for finned tube (W/m 2 .°C), hos: air side heat transfer coefficient for smooth tube (W/m 2 .°C) K: thermal conductivity of tube material (W/m.°C), Kw: thermal conductivity of water (W/m.°C), L: length of tube (m). , Nua: air side Nesselt number, Nuw : inner side Nesselt number, ��: heat transfer rate (Watt), R: thermal resistance, Rew : inner side Reynolds number, T: temperature (°C), Ts: surface temperature (°C), Tm: mean temperature (°C), Ui: inner side overall heat transfer coefficient (W/m 2 .°C), Uo: air side overall heat transfer coefficient (W/m 2 .°C), uw : velocity of water (m/s), m : mass flow rate (kg/s), ∆T: temperature difference (°C), ρw : density of water (Kg/m 3 μw : visocity of water (kg/m.s).