payam rahim mashaei

This paper aims to study the effect of nanofluid on the thermal performance of a heat pipe with three evaporators for satellite equipment cooling. Nanoparicls of Cuo and TiO2 were considerd for modeling. The mathematical expressions of temperature distribution of heat pipe wall, which are analytically derived by separation of variables technique, consist of infinite series that were solved by Matlab software. The accuracy of simulated results was validated against available experimental data and a good agreement was observed between them. The results show that the use of nanofluid instead of water leads to a more temperature reduction of satellite equipment as well as a more temperature uniformity throughout the wall of heat pipe. Moreover, increasing of nanoparticle concentration and reducing nanoparticle diameter have a remarkable effect on the heat transfer enhancement, thermal resistance reduction, and thus thermal performance of heat pipe. Under the best condition, growing CuO nanoparticle with diameter of 10nm up to 8% increases heat transfer coefficient up to 75%. The use of nanofluid reduced the required heat transfer surface and the weight of heat pipe in best cause (8% CuO nanoparticle with diameter 10nm) decreases down to 35%. The outcomes of this paper indicate that metal oxides nanofluids can have a great potential in satellite equipment cooling.

An analytical-numerical study on the thermal behavior of nanofluid in a cylindrical heat pipe is performed to investigate the nanofluid application in air conditioning systems. Pure water and Al2O3-water nanofluid are used as working fluids. A mathematical modeling is developed to predict the heat transferred by the heat pipe between precooling and reheating sections of the air conditioning system. The obtained results by proposed model are validated against experimental data and a good agreement between them is observed. The effect of nanoparticle concentration and size on the amount of energy required in precooling and reheating sections are evaluated. The results reveal that using nanofluid can dramatically decreases the temperature difference between condenser and evaporator sections of a cylindrical heat pipe under constant transferred thermal energy condition. Enhanced condition for precooling and reheating processes is provided for higher concentration and lower size of nanoparticles. Also, not a significant variation in heat transfer is observed by increasing nanoparticles size beyond 40 nm. The findings of this study prove the potential of nanofluid application for air conditioning of buildings located in regions with hot and humid climate.