Heat transfer and fluid flow in the heat pipe system result in thermodynamic irreversibility generating entropy. The minimum entropy generation principle can be used for optimum design of flat heat pipe. The objective of the present work is to minimise the total entropy generation rate as the objective function with different parameters of the flat heat pipe subjected to some constraints. These constraints constitute the limitations on the heat transport capacity of the heat pipe. This physical nonlinear programming problem with nonlinear constraints is solved using LINGO 15.0 software, which enables finding optimum values for the independent design variables for which entropy generation is minimum. The effect of heat load, length, and sink temperature on design variables and corresponding entropy generation is studied. The second law analysis using minimum entropy generation principle is found to be effective in designing performance enhanced heat pipe.

The flow characteristics in the porous wick of a flat heat pipe subjected to boiling and condensation are analysed here using two-phase mixture model. Steady laminar boundary layer flow in the capillary wick structure is considered for both vertical and horizontal orientations. The governing boundary layer partial differential equations are simplified using similarity transformation. The transformed equations are then solved numerically by using shooting iterative technique. Investigation was carried out for the effects of the involved parameters such as saturation and temperature across the boundary layer. The behaviour of non-dimensional numbers due to the orientation of the heat pipe is also discussed. The study confirms that orientation plays a significant role in flow and temperature field.

We report a case of calcified fibroid in a 34 year old reproductive female, persisting for more than nine years, with secondary infertility, without symptoms. Final diagnosis of calcified fibroid was made through radio-diagnosis. When the whole of the tumour is converted into a calcified mass, it is called 'womb stone'. [1] A calcified fibroid in reproductive age group is very rare. Hence we are presenting this case.

The two-phase flow through porous media is an important topic which spans a broad spectrum of engineering disciplines especially in porous heat pipes. Heat pipe is a thermodynamic device that transports heat energy from one location to another with a negligible temperature drop. The aim of the present work is to investigate the phase change mechanisms, namely boiling and condensation, in the flat heat pipe system with different orientation. Governing equations used for the formulation are continuity, mixture momentum, liquid conservation and energy equations. These equations are converted into three ordinary differential equations using similarity transformation and two-phase similarity solutions are obtained for both boiling and condensing flows. In each case, a two phase zone where the liquid and vapour can coexist appears adjacent to the wall. As the heat transfer at the wall gradually enhances, the liquid saturation at the wall approaches to the limiting value, zero, for boiling and unity for condensation. The present work is an attempt to predict numerically the liquid wall saturation, non-dimensional temperature, non-dimensional temperature gradient and effect of Sherwood number during the phase change of water-steam system in the heat pipe for horizontal and vertical cases. Nomenclature