FLAT PLATE PULSATING HEAT PIPES WITH DIFFERENT CHANNEL GEOMETRIES FOR HIGH HEAT FLUX APPLICATIONS

The thermal performance of flat plate pulsating heat pipes with differentchannel geometries was performed in this experimental work. The testswere accomplished with two channel profiles, round and grooved. One ofthe channel geometries, located on the evaporator, can be considered novel,consisting of a round channel with two lateral grooves. Diffusion bondingtechnology was used to manufacture the PHPs made of two copper flatplates. Distilled water was used as the working fluid with a filling ratio of50% (17.9 ml) of the total volume. The pulsating heat pipes were tested atone position (vertical) under heat loads from 20 up to 2000 W. Theexperimental results showed that both flat plate pulsating heat pipesoperates successfully for high heat fluxes. The lateral grooves reduced thethermal resistance, being principally efficient in lower loads. Besides that,the novel channel considerably anticipated the operation startup. Therefore,a much better performance was obtained by the grooved channel PHP,which was constructed from a simple, low cost modification of thefabrication process.

The Solutions of Non-Integer Order Burgers’ Fluid Flowing through a Round Channel with Semi Analytical Technique

The solutions for velocity and stress are derived by using the methods of Laplace transformation and Modified Bessel’s equation for the rotational flow of Burgers’ fluid flowing through an unbounded round channel. Initially, supposed that the fluid is not moving with t = 0 and afterward fluid flow is because of the circular motion of the around channel with velocity Ω R t p with time positively grater than zero. At the point of complicated expressions of results, the inverse Laplace transform is alternately calculated by “Stehfest’s algorithm” and “MATHCAD” numerically. The numerically obtained solutions in the terms of the Modified Bessel’s equations of first and second kind, are satisfying all the imposed conditions of given mathematical model. The impact of the various physical and fractional parameters are also indeed and so presented by graphical demonstrations.