Experimental investigation of effects of frequency and amplitude on flow of nanofluids in oscillation contrlled heat transfer tubes

In the mechanical engineering literature heat transfer researches have been covered extensively and oscillating heat transfer and nanofluid usage is a large part of this endeavor. In this study, oscillation-controlled heat transfer tubes, which was studied and practiced partly before, was investigated. Oscillation-controlled heat transfer tubes are one of the systems used to enhance heat transfer. Oscillation-controlled heat transfer tubes are the systems that increase the amount of heat transferred between cold and hot environments at a considerably amount by using vibrations. This system includes two reservoirs and one capillary tube. Oscillatory flow in the bundle is be induced by a shaker. This study attempts to clarify the characteristics of the system which could not be explored by the earlier studies. Effects of the oscillation and frequency were examined by using different fluids and different tube sizes (1.5 and 2.4 mm inner diameter) in the system. Experiments were conducted for different frequencies between 3 Hz and 15 Hz. In terms of fluids, pure water and water based Aluminum oxide (%2) nanofluid were used. As a result, frequency increased heat transfer up to 9-10 Hz for capillary bundle which have 1.5 mm inner diameter, but a decline was monitored afterwards. This value 7 Hz for capillary bundle which have 2.4 mm inner diameter. In accordance with increase in oscillation amplitude, there was an increase in heat transfer. At 5 Hz, the highest amount of heat was transferred using the minimum amount of energy. In addition, the results of the experiments with nanofluids paralleled that of water. Nanofluids were more profitable than water in some cases. The results were presented in terms of Prandtl number since water and nanofluids have different viscosity values. Even though the results of the experiments conducted on nanofluids were satisfactory enough, future experiments can be implemented by using different nanofluids in different volumes in order to observe the effects of using different fluids and with these new results can be established.