Empirical Investigation of Heating and Kinematic Performance of ZnO Nano Fluid in a Heat Pipe

The authors investigate thermal and dynamic performance of zinc oxide nano fluid in one straight circular heat pipe with 0.2 m in length and 0.006 m in diameter, in this paper. Zinc oxide nanoparticles with two different average diameters (35 and 55 nm) are used to measure and compare values of temperature, thermal resistance, pressure drop and input power of pure water and zinc oxide nanofluid which fills heat pipe as thermal and dynamic properties of working fluid. The experiments are handled with pure water and nano fluid based pure water which contains 1 mg/l to 100 mg/l of nano ZnO. Results show that the thermal resistance is decreased 15 to 66 percentages when the ZnO nanoparticles are injected to the pure water using input power values of 30-60 Watt. In addition, the thermal resistance of a heat pipe decreases as the particle size and concentration of zinc oxide nano fluid increases. Also, the required amount of pumping power and the observed value of pressure drop is increased by the increase in values of Reynolds number and in amount of zinc oxide in nano fluid. The maximum deviation between the amount of pumping power and pressure drop in pure water and nano fluid is reported 92% and 80% using nano fluid with 100 mg/l, 55 nm in diameter of nano zinc oxide and for 50 mg/l, 55 nm in diameter nano zinc oxide, respectively. This value is related to dual effect of increase in both pressure drop and amount of nano zinc oxide.