On the Hydrodynamic Analysis and Heat Transfer Investigation of Forced Oscillated Vertical Annular Fluid Column

Heat transfer from a forced oscillated water column is investigated experimentally and theoretically. Further details of the water flow can be given as mini-scale, vertical, annular, internal, reciprocating and single phase. The inner wall of the stationary concentric element is heated and water is oscillated through the annuli. The data is acquired from the measurements both in the initial transient period and in the pseudo-steady (cyclic) period from the experimental set-up. The effect of the oscillations is observed on the measured temperature field and heat transfer. There is minor radial temperature variation in the water column. Experimental study proved that the frequency, wall heat flux and related wall temperatures are important parameters affecting heat transfer. It is understood that, the effective heat transfer mechanism is enhanced in oscillating flows. Cycle and space-averaged heat convection coefficients are calculated for the present oscillating flows. The physical and mathematical behavior of the resulting heat convection coefficients are analyzed using the data acquired from the experiments. The predicted cycle-space averaged heat convection coefficients using the experimental data are shown to have a logical trend with the experimental observations. The analysis is carried out for different oscillation frequencies at various applied wall heat fluxes while the displacement amplitude remains constant. A novel control volume formulation is introduced in order to investigate pressure distribution and energy balance of water over a cycle for the present reciprocating flow and the formulations are reorganized in order to capture the cycle-averaged energy balance of the control volume. The present study is novel because it appears to be the first paper on the analytical hydrodynamic analysis of forced oscillated vertical annular fluid flow. The present investigation has possible applications in moderate sized wicked heat pipes, solid matrix compact heat exchangers compromising of metallic foams (in some other types of heat exchengers as well), possibly in boilers, filtration equipment, and steam generators.