Experimental Investigation of Oscillation Controlled Heat Transport Tubes

Author(s):  
Omer F. Guler ◽  
Murat K. Aktas

The oscillatory flows are widely used to enhance heat transfer or as an alternative cooling technique. The oscillatory flows in liquids have the potential of augmenting heat transfer as demonstrated in literature. The subject needs to be investigated in order to fully understand the thermal transport mechanism and affecting parameters. In this investigation, heat transfer in an oscillatory pipe flow of water was studied, experimentally for low frequency regime flow conditions. Major research tasks are; setting up of the experimental apparatus, parametric experimental investigation of the convective heat transfer in oscillatory pipe flow and data reduction and analysis. An experimental apparatus was designed and constructed for the experimental investigation. The equipment consist a capillary pipe bundle connecting a cold fluid and a hot fluid reservoir. The effects of the maximum displacement amplitude of the vibrations and vibration frequency on the heat transfer were analyzed with a parametric study. Significant effect of oscillatory flow on the thermal transport compare to pure diffusion was measured. The heat transfer is greatly enhanced as vibration displacement increase. The results of the present investigation will be useful in choosing optimum operation parameters for cooling applications utilizing oscillatory flows.

Author(s):  
Oguz Guven ◽  
Murat K. Aktas ◽  
Yildiz Bayazitoglu

The oscillatory flows are often in order to augment heat transfer rates in various processes. It is also well known fact that nanofluids provide significant enhancement in heat transfer at certain conditions. In this research, heat transfer in an oscillatory pipe flow of both water and water-alumina nanofluid were studied experimentally under low frequency regime flow conditions. The aim of the conducted research is parametric experimental investigation of the convective heat transfer in the oscillatory pipe flow. Firstly, the nanofluids were prepared and thermophysical properties weare measured. The experimental apparatus consist of a capillary pipe bundle connecting two reservoirs which are placed at the top and bottom side of the capillary pipe bundle. Upper reservoir contains the hot fluid while lower reservoir and capillary pipe bundle filled with cold fluid. The oscillatory flow in the pipe bundle is driven by the periodic vibrations of a surface mounted on the bottom end of the cold reservoir. The effects of the maximum displacement amplitude of the vibrations and volumetric concentration of nanoparticles on heat transfer were evaluated based on the measured temperature and acceleration data. It is found that heat transfer rate increases with increasing vibration displacement in the fluid.


Author(s):  
Omer F. Guler ◽  
Oguz Guven ◽  
Murat K. Aktas

The oscillatory flows are often utilized in order to augment heat transfer rates in various industrial processes. It is also a well-known fact that nanofluids provide significant enhancement in heat transfer at certain conditions. In this research, heat transfer in an oscillatory pipe flow of both water and water–alumina nanofluid was studied experimentally under low frequency regime laminar flow conditions. The experimental apparatus consists of a capillary tube bundle connecting two reservoirs, which are placed at the top and the bottom ends of the capillary tube bundle. The upper reservoir is filled with the hot fluid while the lower reservoir and the capillary tube bundle are filled with the cold fluid. The oscillatory flow in the tube bundle is driven by the periodic vibrations of a surface mounted on the bottom end of the cold reservoir. The effects of the frequency and the maximum displacement amplitude of the vibrations on thermal convection were quantified based on the measured temperature and acceleration data. It is found that the instantaneous heat transfer rate between de-ionized (DI) water (or the nanofluid)-filled reservoirs is proportional to the exciter displacement. Significantly reduced maximum heat transfer rates and effective thermal diffusivities are obtained for larger capillary tubes. The nanofluid utilized oscillation control heat transport tubes achieve high heat transfer rates. However, heat transfer effectiveness of such systems is relatively lower compared to DI water filled tubes.


1966 ◽  
Vol 88 (4) ◽  
pp. 359-363 ◽  
Author(s):  
W. R. Penney ◽  
T. B. Jefferson

An experimental investigation has been conducted to investigate the effect of low-frequency, large-amplitude, horizontal oscillations on convection from a heated horizontal wire (0.008 in. dia) to water and ethylene glycol. Frequencies to 4.5 cps and amplitudes to 2.5 in. were employed. Comparison with a previous investigation has shown that, in the range of this investigation, heat transfer for vertical oscillations is greater than for horizontal oscillations. Comparison of data for water and ethylene glycol showed that previous methods of presenting mixed convection (free plus forced convection) data would not suffice for widely varying fluid properties. A correlating method was developed which successfully correlated the data of this investigation but failed to correlate data of previous investigations. Deficiencies of this method are discussed, and recommendations are given for future correlating methods.


Sign in / Sign up

Export Citation Format

Share Document