Effects of micro heat pipe (MHP) cross-sections and orientations on its thermal performance are experimentally investigated in this study. Tests are conducted using five different cross-sections (circular, semicircular, elliptical, semi-elliptical and rectangular) of micro heat pipes having same hydraulic diameter of 3 mm placed at three different inclination angles (0 o , 45 o , 90 o ), where water is used as the working fluid. Evaporator section of the MHP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the MHP are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the MHP is flattened. Thus among all cross-sections of MHP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. Moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within +7%.

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In this paper, the mα-tangent multiplier is used in conjunction with the elastic modulus adjustment procedure (EMAP) for limit load determination. This technique is applied to a number of mechanical components possessing different kinematic redundancies. By specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible stress and strain distributions are generated, and limit loads for practical components are then determined using the mα-tangent method. The procedure ensures sufficiently accurate limit loads within a reasonable number of iterations. Results are compared with the inelastic finite element results and are found to be in satisfactory agreement.