Development of nickel bi-porous wicks for miniature loop heat pipe applications

PurposeMiniature loop heat pipes (MLHPs) are highly efficient passive heat transfer devices, which have considerable advantages over conventional heat pipes. Currently, miniature LHPs with ammonia and water as working fluids have been developed and utilized in electronics cooling within temperature range of 50°C-70°C at any orientation in 1-g conditions.Design/methodology/approachThe authors studied the standard procedure for the development of bi-porous nickel wicks and their characterization. Three different shaped nickel powders were studied, and best fitting nickel powder for electronics cooling application was reported. The manufacturing of bi-porous wick structures was analyzed with parameters such as porosity, permeability, capillary pressure and effective thermal conductivity for efficient performance of MLHP.FindingsThe study investigated the sintering process for number of samples to identify effective sample for the particular application. It is found that carbonyl nickel powder (type 287) with particle size of 2.6-3.3 µm gives promising results. Permeability and porosity were found to be highest in this case.Originality/valueIt is found that carbonyl nickel powder type with particle size gives promising results. Permeability and porosity was found to be highest in this case.

The Influence of Carbonyl Nickel Content on Thermophysical Properties of Metal Polymer Materials Based on Aromatic Polyamide Phenylon

Introducing carbonyl nickel’s fine particles into a thermo-resistant polyamide phenylone can significantly improve thermo-physical characteristics of the CM and extend the operational temperature range of products made from these materials. Introducing carbonyl nickel in the amount of 5 – 20 mass %, thermo-resistance of phenylon C-1 increases by 10-30 degrees (most significantly in the case of a 20 % content), thermal conductivity grows by 38 %, and temperature conductivity of composite materials ranges from 1.75∙10-4 to 1.9∙10-4, which is 1.3 - 1.4 times as high as that of the initial phenylon.