This paper represents the experimental investigation of closed thermo-syphon for checking the thermal performance. The thermo-syphon selected for this application is 25.4 mm inner diameter, 1mm thick and 500 mm length designed to dissipate 20 to 60 watt. The working fluid used is ethanol and the second trial was done by addition of suspended particles of 10 nm aluminium powder in solution of ethanol 10 % by volume. The four factors were studied; the effect of heat load, the effect of working fluid types, the effects of flow rates of cooling water and the inclination with vertical. It is observed that heat transfer increases as heat load increases, heat transfer increases by using Al2O3 Nano fluid than ethanol. As flow rates of cooling water decreases the heat transfer increases. The maximum heat transfer takes place at vertical orientation (i.e.90⁰) and also as the inclination decreases the heat transfer also decreases
