5. Heat pipe experiments

structures made form Cu powder with grain size 50 μm and 100 μm and two wick structures

Figure 17. Influence of the wick structure on LHP cooling efficiency with working fluid water depending on loaded heat.

Comparing the results of dependence of temperature on input power of IGBT cooled by LHP with variants of sintered wick structure, the LHP with nickel wick structure does not show so good properties of heat removal than LHP with copper wick structure. Comparing the temperature curves of the LHP with first wick structure (made of Cu powder 50 μm) and LHP with second wick structure (made of Cu powder 100 μm), it is seen that both LHP have almost the same results at heat load of up to 200 W. At higher input power than 200 W loaded in to IGBT is

made from Ni powder grain size 20 μm and 10 μm were compared.

Figure 16. Influence of working fluid amount on LHP operation.

158 Porosity - Process, Technologies and Applications

The next experiments were performed in frame scientific research of porous wick heat pipes, where the ability of heat transfer depending on wick structure and working fluid is investigated. The popularity of porous wick heat pipe and lack of experiments performed with them were the reason to realize experiment which deals with heat pipes with sintered wick structures made from copper powders. This section describes manufacturing process of wick heat pipe, experimental measurement of heat transfer ability of heat pipe, and mathematical calculation of heat transport limitation of heat pipes.
