This paper examines the design of heat exchanger made of copper pipe for cooling small space system and the effects of water and CuO/distilled water like coolants channeling inside the heat exchanger to increase the transportation of heat between the compartment and the heat exchanger and comparison between them. The nano-fluid was prepared by dispersing a nanoparticle (CuO) in base fluid (distilled water). Nano-fluid with a nominal diameter of 50 nm at volume frictions (0.27 vol. %) at compartment temperature was used for these investigations. The analysis showed that secondary cooling system by means of nano-fluid (CuO/distilled water) has advantages in enhancing the flow rate heat transfer, best from base fluid (distilled water) also in Nusselt number.
